5 10 10 10 15 10 20 10 10 10 10 10 10 5 30 10 5 5 10 5 10 10 5 5 5 5 5 30 20 5 50 55 25 30 10 10 5 10 5 5 10 10 20 10 10 10 10 10 5 10 80 85 10 15 10 5 25 30 10 15 10 10 15 10 20 65 50 80 80 3 10 10 10 10 10 10 10 10 10 5 10 85 80 10 10 10 5 5 85 80 20 80 80 65 20 10 10 25 20 25 75 5 3 10 5 20 5 10 10 10 5 10 5 5 10 8 10 10 10 10 10 5 5 10 10 10 5 70 70 70 59 Ktc Tt Ktc Kgd Kgb Tt Qya Tt Qya Ktc Ktc Qa Qoa Tt Qoa Qf Kgd Qyf Ktc Kat Kat Kat Kgb J^m Kgb Qw J^m Ttu af Qoa Ttu Qoa Qoa J^m Qoa J^m Ttu Qya Ttu Ttu Qa+Qya Tt Qya Ttl Ttu Ttl Qof J^m Qya+Qoa Qa Tt Qds Qvoa Qds Qa Tt Kgd Qof Qp Qvof J^m Kat Kt Kat Kat Kgd Qvoa Kat Kat Kt Qof Qvof Kgd J^m Qvof Qls Tt Qvof Qa Qa Qoa Qa J^m Kat Ttl Ttl Qya Kgd Kgd Qoa Qya Qya Qya Tt Qya Qa Kgd Qya J^m Qoa Qya Ttu Ttu Qya Qya Qa Ktc Tt Ttu Ttu D U D U D U D U J^m Lancaster Fault J^m U D U D Qa+Qya Qa+Qya Qa+Qya Qa+Qya U D Qp Qoa Qya+Qoa Qof Qof Qof Ttl Qoa Ttl J^m FAULT Qls? Qls? Qls? Qls? Jmg J^m Hot Springs Tt Qvof Ttl Ttl Ttl Ttl Ttl Ttl Qvof FAULT CREEK AGUANGA TEMECULA J^m J^m J^m Kgb Ttu Ttu Tt Qa J^m Tt Qya Qof Qa Qvoa Qls Qw Kgd Ktc Ktc Ktc Kgd Kgd Kgd Kat Kgd Qvof Kgd Kt Kt GN 240 MILS 13 0 02 1MIL MN UTM GRID AND 1988 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET 1/ 2 Contour Interval 20 Feet Dotted lines 10 Feet SCALE 1:24 000 8000 FEET 3000 4000 5000 .5 2 KILOMETERS 0 1 1/ 2 0 1 2 MILES 0 1000 2000 6000 7000 REFERENCES CITED Bull, W.R., 1991, Geomorphic responses to climatic change: New York, Oxford University Press, 326 p. Gastil, G., Girty, G., Wardlaw, M., and Davis, T., 1988, Correlation of Triassic-Jurassic sandstone in peninsular California (abs.): Geological Society of America Abstracts with Programs, v. 20, no. 3, p. 162. Germinario, M. P. 1982, The depositional and tectonic environments of the Julian Schist, Julian, California: Unpublished M.S. thesis, San Diego State University, San Diego, California, 95 p. Golz, D.J., Jefferson, G.T., and Kennedy M.P., 1977 , Late Pleistocene vertebrate fossils from the Elsinore Fault Zone. Journal of Paleontology 51 (4): p. 864-866. Hanley, J.B., 1951, Economic Geology of the Rincon Pegmatites, San Diego County, California: California Division of Mines, Special Report 7-B, 24 p., scale 1:24,000. Hudson, F.S., 1922, Geology of the Cuyamaca region of California, with special reference to the origin of nickeliferous pyrrhotite: University of California Publications in Geological Sciences Bulletin, v. 13, p. 175-252. Irwin, W.P., and Greene, R.C., 1970, Studies related to wilderness primitive areas, Agua Tibia, California: U.S. Geological Survey Bulletin 1319-A, 19 p., scale 1:48,000. Jennings, C. W. and Bryant, W. A., 2010, Fault activity map of California: California Geological Survey Geological Data Map No. 6, scale 1:750,000. Kennedy, M.P., 1977, Recency and character of faulting along the Elsinore fault zone in southern Riverside County, California: California Division of Mines and Geology, Special Report 131, 12 p., scale 1:24,000. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm Kennedy, M. P., 2000a, Geologic map of the Pechanga 7.5' quadrangle, San Diego and Riverside, counties, California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm. Kennedy, M. P., 2000b, Geologic map of the Pala 7.5' quadrangle, San Diego and Riverside, counties, California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm. Kennedy, M. P., 2011, Geologic map of the Boucher Hill 7.5' quadrangle, San Diego County California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm. Larsen, E. S., Jr., 1948, Batholith and associated rocks of Corona, Elsinore and San Luis Rey quadrangles, southern California: Geological Society of America Memoir 29, 182 p., plate 1, scale 1:125,000. Matti, J. C., Cossette, P.M., and Hirschberg, D.M. , 2010, Classification of surficial materials, Inland Empire Region, southern California: Conceptual and operational framework: U.S. Geological Survey Scientific Investigations Report, in press. Mann, J.F., 1955, Geology of a portion of the Elsinore Fault Zone California: Division of Mines and Geology Special Report 43, 22 p., scale 1:62,500. Olmstead, F.H., 1955, Geologic map of La Jolla Indian Reservation, San Diego County, California: Unpublished geologic map, U.S. Geological Survey, Ground Water Branch, Sacramento, California, scale 1:24,000. Pajak III, A. F., Scott, E., and Bell, C.J., 1996, A review of the biostratigraphy of Pliocene and Pleistocene sediments in the Elsinore Fault Zone, Riverside County, California, in Bell, C.J. and Sumida, S., editors, The uses of vertebrate fossils in biostratigraphic correlation: PaleoBios, v.29, p. 28-49. Repenning, C.A., 1987, Biochronology of the microtine rodents of the United States, in Woodburne, M.O, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles, University of California Press, p. 236-268. Reynolds, R.E., and Reynolds, R.L., 1990a, A new late Blancan faunal assemblage from Murrieta, Riverside County, California: San Bernardino County Museum Association Quarterly, v. XXXVVII, p. 34. _______, 1990b, Irvingtonian? Faunas from the Pauba Formation, Temecula, Riverside County, California: San Bernardino County Museum Association Quarterly, v. XXXVVII, p. 37. _______, 1993, Rodents and Rabbits from the Temecula Arkose, in Reynolds, R. E. and Reynolds, J., editors, Ashes, faults and basins: San Bernardino County Museum Association Special Publication 93-1, p. 98-100. Rogers, T.H., 1965, Santa Ana Sheet: California Division of Mines and Geology Geologic Map of California, scale 1:250,000. Sharp, R.V., 1967, San Jacinto fault zone in the Peninsular Ranges of southern California: Geological Society of America Bulletin, v. 78, p. 705-729. Shaw. S.E., Todd, V.R., and Grove, M., 2003, Jurassic peraluminous gneissic granites in the axial zone of the Peninsular Ranges, southern California, in Johnson, S.E., Paterson, S.R., Fletcher, J.M., Girty, G.H., Kimbrough, D.L., and Martin-Barajas, A., eds., Tectonic evolution of northwestern Mexico and southwestern USA: Boulder, Colorado, Geological Society of America Special Paper 374, p. 157-183. Streckeisen, A.L., 1973, Plutonic rocks—classification and nomenclature recommended by the IUGS Subcommission on Systematics of Igneous Rocks: Geotimes, v. 18, pp. 26-30. Tan, S. S., and Kennedy, M. P., 2013, Geologic map of the Aguanga 7.5' quadrangle, San Diego and Riverside, Counties, California: California Geological Survey Preliminary Geologic Map website, http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm. Todd, V.R., 2013 (in press), Geologic map of the Julian 7.5’ quadrangle, San Diego County, California: U.S. Geological Survey Open-File Report 94-16, scale 1:24,000. Weber, F.H., Jr., 1963, Geology and mineral resources of San Diego County, California: California Division of Mines and Geology County Report 3, Plate 1, scale 1:120,000. Woodburne, M. O., 1987, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles University of California Press, 336 p. GEOLOGIC SUMMARY Geological mapping of the Vail Lake 7.5’ quadrangle was conducted June 2002 - July 2003 and revised June 2013 by the Department of Conservation, California Geological Survey pursuant to the U.S. Geological Survey STATEMAP cooperative mapping award # 02HQAG0018. The quadrangle lies between 33° 22.5' and 33° 30.0' N. latitude and 116° 52.5' and 117° 00' W. longitude in the northwestern corner of the Borrego Valley 30’x 60’ quadrangle (Fig. 2). The study is aimed at providing new information for use by earth scientist, engineers, planners and developers in decision making related to geologic hazards in the process of long term land use planning. Structurally the Vail Lake quadrangle lies between the northwest trending, predominately right-slip San Jacinto and the parallel predominately oblique-(up to the north) right-slip Elsinore Fault Zones, two major elements of the San Andreas Fault System (Fig. 3). It is transected by the Agua Caliente Fault Zone which includes from north to south: the Lancaster-Hot Springs, Temecula Creek and Aguanga faults (Fig. 3). These faults are part of a series of faults that lie sub parallel to and splay from the Elsinore Fault Zone between Lake Elsinore and Murrieta (Mann, 1955, Rogers, 1965, Kennedy, 1977). Northeast of Vail Lake the Lancaster-Hot Springs Fault appears to merge with the Murrieta Hot Springs Fault and then with the Wildomar Fault segment of the Elsinore Fault Zone (Kennedy, 1977). The Aguanga and Temecula Creek faults can’t be traced north of Vail Lake and either die out there or step right to the Lancaster-Hot Springs Fault. To the southeast It appears likely that the Lancaster-Hot Springs, Temecula Creek and Aguanga faults merge with the Superstition Mountain, San Felipe and Earthquake Valley faults respectively (Jennings and Bryant, 2010). Based on faulted sedimentary sequences the Agua Caliente Fault Zone has Quaternary elements, however to date there is no evidence of Holocene activity (Jennings and Bryant, 2010). The Vail Lake quadrangle is divided into two distinctive physiographic provinces by Temecula Creek and the underlying Temecula Creek Fault. Southwest of Temecula Creek lie the steep northeast facing slopes of the Agua Tibia-Palomar Mountain structural block, which rise abruptly from less than 1500’ near Vail Lake to 5077’ at Eagle Crag, a distance of approximately 8 miles. Northeast of Temecula Creek the area is underlain by rolling hills and intermountain valleys that rise and fall from 1500’ at Temecula Creek to over 2000 feet in the northernmost part of the quadrangle, a distance of approximately 3 miles. The Agua Tibia-Palomar Mountain block is a horst being rapidly elevated by oblique slip between the Elsinore Fault Zone to the southwest and the Temecula Creek and Aguanga faults on the north The rapid uplift is evidenced by the over steepened and deeply dissected Quaternary alluvial fan deposits that mantle the slopes both here and in the adjacent Pechanga, Boucher Hill, and Aguanga quadrangles (Kennedy 2000; Kennedy, 2011; Tan and Kennedy, 2013). The Agua Tibia-Palomar Mountain block is underlain by Mesozoic metamorphic and plutonic rock. The metamorphic rocks are Triassic and Jurassic schist, gneiss and quartzite that have been intruded by Jurassic and Cretaceous plutonic rocks of the Peninsular Ranges batholith (PRB). Within the Vail Lake quadrangle the plutonic rocks include Gabbro of Agua Tibia Mountain and unnamed bodies of granodiorite, tonalite and gabbro. The rolling hill and intermountain valleys to the northeast of Temecula Creek are underlain by Pliocene and Pleistocene sedimentary rocks composed of locally derived fluviatile detritus and Quaternary unconsolidated alluvium and wash deposits. The Plio-Pleistocene sedimentary succession, which has total combined thickness of less than 1000’ is draped over and in part faulted against a Mesozoic metamorphic and plutonic basement complex. The faulted part is confined to a trough centered near Vail Lake. The trough is defined on its northeastern side by the Hot Springs Fault and on its southwest side by the Aguanga and Temecula Creek faults (Fig. 3). The area has been receiving sediment, since the early Pliocene via Cahuilla and Temecula creeks. TRIASSIC-JURASSIC METASEDIMENTARY ROCKS: The Triassic-Jurassic metasedimentary rocks (J^m) consist mostly of quartzofelspathic schist, pelitic schist, quartzite, and metabreccia. These rocks have been informally correlated with the Julian Schist by earlier workers (Hanley, 1951; Olmstead, 1955; Irwin and Greene, 1970). The protolith of the Julian Schist, based on relic depositional structures including graded bedding and Bouma sequences, appears to be a submarine fan sequence (Germinario, 1982). The age of the Julian Schist is considered to be Triassic based on a fossil ammonite (Hudson, 1922). Gastil and others (1988) report a detrital zircon Triassic-Jurassic depositional age for the protolith. The Julian Schist can be no younger than the Middle Jurassic plutonic rocks that intrude it (Shaw and others, 2003). In addition these rocks are similar in composition and metamorphic character to parts of Larsen’s (1948) Bedford Canyon Formation which crops out immediately east of Temecula within the Santa Ana Mountains along the western side of the Elsinore Fault Zone (Kennedy, 1977). JURASSIC METAGRANITIC ROCKS: The Jurassic metagranitic rocks (Jmg) are gneissic and composed mostly of dark gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granodiorite. The unit has intruded and assimilated “Julian Schist” and is characterized by elongated remnant inclusions of it. These inclusions range in size from an inch or so to more than 30 feet and have their long axis in the foliation plane. They are tentively correlated with the granodiorite of Harper Creek mapped in the Julian area by Todd (1994). They are described in detail and assigned a Middle Jurassic (U-Pb) age of 170-160 Ma by Shaw and others (2003). CRETACEOUS GRANITIC ROCKS: The Cretaceous granitic rocks based on the classification of Streckeisen (1973), see Fig. 3, are mostly tonalite and granodiorite but range in composition from gabbro to monzogranite. They include the tonalite of the Coahuila Valley pluton, (Ktc), the gabbro of Agua Tibia Mountain, (Kat), granodiorite (Kgd), tonalite (Kt), and gabbro (Kgb). Tonalite of the Cahuilla Valley Pluton (Ktc) crops out in the northeastern part of the quadrangle. It consists mostly of light-gray, coarse-grained, relatively homogeneous hornblende-biotite tonalite. Sphene is a conspicuous accessory mineral occurring as large, honey-colored euhedral crystals. Other accessory minerals include epidote (pistacite and allanite), zircon, apatite, tourmaline, and opaque minerals. These rocks were described in detail by Sharp (1967) and are part of his Cahuilla Valley pluton. Gabbro of Agua Tibia Mountain (Kat) crops out in the Agua Tibia-Palomar Mountain block. The rock is mostly a dark-gray hornblende gabbro that ranges from medium to coarse grained and is either structureless, foliate, or layered They were correlated with the San Marcos Gabbro of Larsen (1948) by Irwin and Greene (1970). They were later described and mapped as the Gabbro of Agua Tibia Mountain for their unique character and limited outcrop within the Pala and Pechanga quadrangles (Kennedy, 2000a, 2000b). Granodiorite (Kgd) crops out south of the Temecula Creek Fault and underlies most of the southwestern two thirds of the quadrangle. These rocks were originally described within the Vail Lake quadrangle by Irwin and Greene (1970) and correlated with the Woodson Mountain Granodiorite of Larsen (1948). Rounded masses of light-colored granodiorite are common on ridge crest and slopes, and many of these appear to be residual boulders lying on deeply weathered parent rock. Though they are mostly granodiorite approximately 15 - 20 percent are tonalite and as much as another 5 -10 percent are granite and quartz monzanite. The rock is light-gray to white, coarse- to very coarse-grained hornblende-biotite granodiorite and has a weak foliation marked by the planar oriented biotite. Tonalite (Kt) crops out in the Agua Tibia Mountains in a less than 1 square mile region along the southwester margin of the quadrangle and in a less than 2 square mile exposure in the southeastern corner of the quadrangle. The rock is typically massive, medium- to coarse-grained, light-gray, hornblende-biotite tonalite and in lesser amounts granodiorite and monzogranite. The contacts between tonalite and granodiorite are gradational and therefore only approximate. In large part these rocks are lithologically similar to and tentatively correlated with rocks 30 miles (50 km) to the southeast within the Julian quadrangle where they were described in detail, assigned a zircon U-Pb isotopic age of 90 – 100 Ma and given the informal name “tonalite of Granite Mountain” (Todd, 2013). Like the Jurassic plutons, they intrude Julian Schist and are locally characterized by remnant inclusions of it. Gabbro (Kgb) crops out in the northwest corner of the quadrangle approximately 1 mile west of Vail Lake Dam. It is mostly massive, coarse-grained, dark-gray and black, biotite-hornblende-hypersthene gabbro with lesser amount of quartz diorite and tonalite. PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS: The Mesozoic basement rocks are overlain by fluviatile, coarse- and medium-grained arkosic sandstone (Temecula Arkose), medium- and fine-grained, fluviatile sandstone and conglomerate (Pauba Formation) and pebble to boulder fan deposits (Dripping Springs Formation). The Temecula Arkose of Mann, (1955) has been subdivided into two informal parts in this study which include a lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale yellowish-brown, olive-gray dark-yellowish-brown, fine-, medium- and coarse- grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the “upper part” of the formation. Golz and others (1977) reported the exposed thickness of the Temecula Arkose to be approximately 500 m (1640’) to the east in the adjacent Pechanga quadrangle, 125 m (410’) at Vail Lake and 85 m (279’) at Radac. A 1947 wildcat petroleum prospect (Tyrrel #1), located on the northern flank of Temecula Creek approximately 1 mile south east of Vail Lake penetrated 312’ of Temecula Arkose (Mann, 1955. The hills to the north and east of the well are underlain PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS: (CONTINUED): by more than 325’ of Temecula Arkose suggesting that the total combined thickness at Vail Lake is in excess of 600’. The Temecula Arkose has an early Pliocene through late Pliocene age (~ 1.9 – 4.6 Ma) based on fossil vertebrate assemblages from Temecula, Radec, Vail Lake and Butterfield Valley (Golz and others, 1977; Kennedy, 1977; Reynolds and Reynolds, 1993; Pajak and others, 1996). Kennedy (1977) assigned the unit a late Pliocene Blancan 1V-V mammal age (2.2 to 2.8 Ma) based on vertebrate assemblages collected east of the quadrangle. Assemblages include Nannippus, Hypolagus, Tetrameryx, Equus, and Odocoileus (Golz and others, 1977). Later work established the first occurrence of Tetrameryx as Irvingtoninan 1 rather than late Blancan (Woodburne, 1987), placing the Temecula Arkose age nearer 1.9 Ma than 2.2 Ma. In addition, a microtine fauna from this unit in the Radec area was reported to have an age of 4.6 Ma (Blancan 1) (Repenning, 1987) which would suggest a depositional period that extended from early Pliocene into the lower Pleistocene. The Pauba Formation of Mann, (1955) is moderate- yellowish-brown, poorly-consolidated, cross-bedded, medium- and coarse-grained sandstone, and cobble conglomerate. First described in print by Mann (1955) and later by Kennedy (1977) for exposures at Rancho Pauba located about 5 km southeast of Temecula. A vertebrate fauna from the Pauba Formation is reported to be of late Irvingtonian and early Rancholabrean Land Mammal Age (Reynolds and Reynolds, 1990a; 1990b), however, the Rancholabrean age is in question (Pajak, and others, 1996). The Dripping Springs Formation of Mann, (1955) is light-brown, poorly- consolidated, pebble, cobble and boulder fanglomerate. First described by Mann (1955) and later by Kennedy (1977) for exposures south of Highway 79 along the eastern margin of the map in the Dripping Springs corridor. It is considered to be equivalent to the old and very old alluvial fan deposits of the area (middle to early Pleistocene). QUATERNARY SURFICIAL DEPOSITS: The surficial Quaternary sedimentary deposits of the area include alluvial wash, fan, and valley fill, The alluvial fan deposits are those deposited in fans along the mountain fronts. The alluvial flood plain deposits are those deposited in flood plains in the valley floors. The classification of the surficial Quaternary sedimentary deposits is modified from the U.S. Geological Survey, Classification of surficial materials, inland empire region, southern California: Conceptual and operational framework, described by Matti and others (2010). Inherent to this classification is the fact that the surficial deposits have been deposited continuously, albeit at different rates, throughout the Quaternary Period and each of the four basic lithostratigaphic units mapped (alluvial wash, fan and alluvial valley fill deposits) represent often interfingered time transgressive facies. The parameters used in this modified classification include: 1) physical properties and lithologic features, e.g. consolidation, induration, fabric, grain size, sorting, etc., 2) genesis and geomorphic setting, e.g. alluvial fan, alluvial valley fill and alluvial wash deposits) and 3) age determinations, e.g. radiometric analyses, paleontology, pedogenic soil characteristics, desert varnish, vegetation, degree of incision, etc. SURFICIAL QUATERNARY UNITS INCLUDE: 1). “Modern surficial deposits” which are those being deposited actively or intermittently active over the past few hundred years. Their soil development is slight to non-existent. They are labeled Qw, Qf and Qa (alluvial wash, alluvial fan and alluvial valley fill deposits). 2). “Young surficial deposits” which are those that were deposited during the Holocene and latest Pleistocene or since the Holocene-to-Pleistocene climatic transition (Bull, 1991). They are slightly dissected, have slight soil development, and little if any pavement or varnish. They are labeled Qyf and Qya (young alluvial fan and young alluvial valley fill deposits). 3). “Old surficial deposits” which are those that were deposited during the middle to late Pleistocene and spanning the period of approximately 500ka to about 15ka. They have moderately dissected surfaces, good soil development, minor clay films, and moderate varnish and pavement. They are labeled Qof and Qoa (old alluvial fan and old alluvial valley fill deposits). 4). “Very old surficial deposits” which are those that were deposited during the early to middle Pleistocene or approximately 1 Ma to 500ka. They have well dissected surfaces, strong soil development, thick clay films and well developed varnish and pavement. They are labeled Qvof and Qvoa (very old alluvial fan and very old alluvial valley fill deposits). QUATERNARY LANDSLIDE DEPOSITS: Highly fragmented to largely coherent landslide deposits. Unconsolidated to consolidated. Most mapped landslides contain scarp area as well as slide deposit. Most reactivated in part during Holocene. Question mark indicates that the landslide is questionable. ACKNOWLEDGEMENT OF PREVIOUS GEOLOGIC MAPPING: Bedrock contacts and faults in the mountainous southwestern half of the quadrangle are modified from Weber (1963), Rogers (1965) and Irwin and Greene (1970). Geological mapping within the sedimentary succession in the vicinity of Vail Lake by J. F. Mann (1955) proved very useful in developing a better understanding of the Plio-Pleistocene stratigraphy of the area. Modifications of all earlier work was based on new mapping and observations made from large scale stereo air photography including USDA 1953 (scale 1:24,000) and Riverside County, 1990 (scale 1:24,000) as well as from Google Earth imagery. Figure 3 - Map showing the location of the Vail Lake, Aguanga Palomar Observatory and Boucher Hill 7.5’ quadrangles with respect to the Elsinore, Agua Caliente and San Jacinto fault zones. EXPLANATION Fault-- dashed where inferred 116° 15' 33° 30' 33° 15' 116° 15' 117° 00' 33° 15' 33° 30' 117° 00' Aguanga 7.5' quadrangle Palomar Obs. 7.5' quadrangle Vail Lake 7.5' quadrangle Boucher Hill 7.5' quadrangle San Jacinto Fault Zone Hot Springs Fault Temecula Creek Fault Agua Tibia- Palomar Mt. Block Fault Zone Lake Henshaw Elsinore Murrieta Hot Springs- Lancaster- Agua Caliente Fault Zone Vail Lake Trough Aguanga Fault Borrego Valley 1:100,000-scale Quadrangle Miles 0 10 20 30 Aguanga Beauty Mt. Bucksnort Mt. Collins Valley Clark Lake Rabbit Pk. Oasis Boucher Hill Palomar Observatory Borrego Springs Hot Springs Mt. Borrego Palm Canyon Clark Lake Fonts Point Seventeen Palms Rodriquez Mt. Mesa Grande Warners Ranch Ranchita Tubb Canyon Borrego Sink Borrego Mt. Shell Reef Ramona Santa Ysabel Julian Earthquake Valley Whale Peak Harper Canyon Borrego Mt. S.E. Vail Lake Figure 2 - Index map showing the location of the Vail Lake and other 7.5' quadrangles in the Borrego Valley 1:100,000-scale quadrangle. CGS OFR 96-06 & CD 2000-008 San Pasqual FY 2002-03 FY 2005-06 FY 2006-07 Mapping completed under STATEMAP Revised 2011 Revised 2013 Revised 2013 N MAP SYMBOLS U D Contact - Contact between geologic units; dashed where approximately located; dotted where concealed. Fault - Solid where accurately located; dashed where approximately located; dotted where concealed. U = upthrown block, D = downthrown block. Arrow and number indicate direction and angle of dip of fault plane, queried where uncertain. Anticline - Solid where accurately located; dashed where approximately located; dotted where concealed. Single arrow indicates direction of plunge. Syncline - Solid where accurately located; dashed where approximately located; dotted where concealed. Single arrow indicates direction of plunge. Landslide—Arrows indicate principal direction of movement. Queried where existence is questionable. Strike and dip of sedimentary beds Strike and dip of metamorphic foliation Inclined Vertical Strike and dip of joints Inclined Vertical 55 5 70 Qls? 55 ? Qw Qf Qa af Qya Qoa Qa+ Qya Qyf Qof Qya+ Qoa Qvof Qvoa Qls Tt Ttu Ttl Qp Qds Kgd Kat Ktc Kt Kgb Jmg J^m JURASSIC CENOZOIC MESOZOIC Holocene Pleistocene Pliocene QUATERNARY TERTIARY CRETACEOUS TRIASSIC CORRELATION OF MAP UNITS Quartz Syenite Quartz Monzonite Quartz Monzodiorite Syenite Monzonite Monzodiorite Granite Alkali-feldspar Granite Tonalite Diorite Syenogranite Granodiorite Monzogranite Quartz Diorite 90 65 35 10 5 20 60 Q Q A P 60 20 5 60 Figure 1 - Classification of plutonic rock types (Streckeisen, 1973). A - alkali feldspar; P - plagioclase feldspar; Q - quartz. MODERN SURFICIAL DEPOSITS Sediment that has been recently transported and deposited in channel and washes, on surfaces of alluvial fans and alluvial plains, and on hill slopes and in artificial fills. Soil-profile development is non-existant. Includes: Artificial fill (late Holocene)—Compacted manmade fill deposits adjacent to Vail Lake spillway. Wash deposits (late Holocene)—Unconsolidated bouldery to sandy alluvium of active and recently active washes. Alluvial fan deposits (late Holocene)—Active and recently active alluvial fans. Consists of unconsolidated, bouldery, cobbley, gravelly, sandy, or silty alluvial fan deposits, and headward channel parts of alluvial fans. Trunk drainages and proximal parts of fans contain greater percentage of coarse-grained sediment than distal parts. Alluvial flood plain deposits (late Holocene)—Active and recently active alluvial deposits along canyon floors. Consists of unconsolidated sandy, silty, or clay-bearing alluvium. Does not include alluvial fan deposits at distal ends of channels. YOUNG SURFICIAL DEPOSITS Sedimentary units that are slightly consolidated to cemented and slightly to moderately dissected. Alluvial fan deposits typically have high coarse-fine clast ratios. Young surficial units have upper surfaces that are capped by slight to moderately developed pedogenic-soil profiles. Includes: Young alluvial fan deposits (Holocene and late Pleistocene)—Mostly poorly- consolidated and poorly-sorted sand, gravel, cobble and boulder alluvial fan deposits. Young alluvial flood plain deposits (Holocene and late Pleistocene)—Mostly poorly-consolidated, poorly-sorted, permeable flood plain deposits. MODERN AND YOUNG SURFICIAL DEPOSITS UNDIVIDED Active alluvial flood plain and young alluvial flood plain deposits undivided (late Holocene and Pleistocene)—See descriptions of individual deposits. OLD SURFICIAL DEPOSITS Sediments that are moderately consolidated and slightly to moderately dissected. Older surficial deposits have upper surfaces that are capped by moderate to well-developed pedogenic soils. Includes: Old alluvial fan deposits (late to middle Pleistocene)—Reddish-brown, gravel and sand alluvial fan deposits that are usually indurated and slightly dissected. Old alluvial flood plain deposits undivided (late to middle Pleistocene)—Fluvial sediments deposited on canyon floors. Consists of moderately well consolidated, poorly-sorted, permeable, commonly slightly dissected gravel, sand, silt, and clay-bearing alluvium. YOUNG AND OLD SURFICIAL DEPOSITS UNDIVIDED Young alluvial flood plain deposits and old alluvial flood plain deposits undivided (Holocene and late to middle Pleistocene)—See descriptions of individual deposits. VERY OLD SURFICIAL UNITS Sediments that are slightly to well consolidated to indurated, and moderately to well dissected, Upper surfaces are capped by moderate to well-developed pedogenic soils. Includes: Very old alluvial fan deposits (middle to early Pleistocene)—Mostly well-dissected, well-indurated, reddish-brown sand and gravel alluvial fan deposits. Very old alluvial flood plain deposits (middle to early Pleistocene)—Fluvial sediments deposited on canyon floors. Consists of moderately to well-indurated, reddish-brown, mostly very dissected gravel, sand, silt, and clay-bearing alluvium. Landslide deposits (Holocene to Pleistocene)—Highly fragmented to largely coherent landslide deposits. Unconsolidated to consolidated. Most mapped landslides contain scarp area as well as slide deposit. Question mark indicates that the landslide is questionable. SEDIMENTARY ROCKS Dripping Springs Formation (early to late Pleistocene)—Light-brown, poorly- consolidated, pebble, cobble and boulder fanglomerate. Equivalent to Qof. See description in Geologic Summary for more detail. Pauba Formation (early to late Pleistocene)—Moderate-yellowish-brown, poorly-consolidated, cross-bedded, medium- and coarse-grained sandstone, and cobble conglomerate. See description in Geologic Summary for more detail. Temecula Arkose (early to late Pliocene)—The Temecula Arkose is here subdivided into two informal parts. A lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale yellowish-brown, olive-gray dark yellowish-brown, fine-, medium- and coarse-grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the "upper part" of the formation. See description in Geologic Summary for more detail. PLUTONIC ROCKS (See Figure 1 for classification). Tonalite of the Cahuilla Valley Pluton (mid-Cretaceous)—Light-gray, coarse-grained, relatively homogeneous hornblende-biotite tonalite. Gabbro of Agua Tibia Mountain (mid-Cretaceous)—Dark-gray hornblende gabbro that ranges from medium- to coarse-grained and is structureless, foliate, or layered. Granodiorite (mid-Cretaceous)—Light-gray to white, coarse- to very coarse-grained hornblende-biotite granodiorite. It has a weak foliation marked by the planar oriented biotite. Tonalite (mid-Cretaceous)—Light-gray, massive, medium- to coarse-grained, hornblende-biotite tonalite. Gabbro (mid-Cretaceous)—Dark-gray and black, massive, coarse-grained, biotite-hornblende-hypersthene gabbro with lesser amounts of quartz diorite and tonalite. METAMORPHIC ROCKS Metagranitic rocks (Jurassic)—Mostly dark-gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granite. Metasedimentary rocks (Jurassic and Triassic)—Mostly quartzofeldspathic schist, pelitic schist, quartzite, and metabreccia. DESCRIPTION OF MAP UNITS Qw Qf Qa af Qya Qoa Qvof Qvoa Qls Kgd Kat Ktc Kt Kgb Qa+ Qya Jmg Tt Ttu Ttl J^m Qof Qyf Qp Qds Qya+ Qoa C GS S G S A M P S U C Coordinate System: Universal Transverse Mercator, Zone 11N, North American Datum 1927. Topographic base from U.S. Geological Survey Vail Lake 7.5-minute Quadrangle, 1953 (Photorevised 1988). This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP Award no. 02HQAG0018 116°52'30'' 33°30' Prepared in cooperation with the U.S. Geological Survey, Southern California Areal Mapping Project 116°45’ 33°30' 33°22'30” 116°52'30'' 33°22'30” 116°45’ STATE OF CALIFORNIA – EDMUND G. BROWN JR., GOVERNOR THE NATURAL RESOURCES AGENCY – JOHN LAIRD, SECRETARY FOR NATURAL RESOURCES DEPARTMENT OF CONSERVATION – MARK NECHODOM, CONSERVATION DIRECTOR CALIFORNIA GEOLOGICAL SURVEY JOHN G. PARRISH, Ph.D., STATE GEOLOGIST PRELIMINARY GEOLOGIC MAP OF THE VAIL LAKE 7.5’ QUADRANGLE, CALIFORNIA PRELIMINARY GEOLOGIC MAP OF THE VAIL LAKE 7.5' QUADRANGLE, SAN DIEGO AND RIVERSIDE COUNTIES, CALIFORNIA: A DIGITAL DATABASE Version 1.1 By Michael P. Kennedy 1 2003 (Revised 2014) Digital Preparation by Matt D. O’Neal 2 , Carlos I. Gutierrez 2 and Apri Mertz 3 1. California Geological Survey, 888 South Figueroa Street, Suite 475, Los Angeles, CA 90017 2. California Geological Survey, 801 K Street, MS 12-32, Sacramento, CA 95814 3. U.S. Geological Survey, Department of Earth Sciences, University of California, Riverside Copyright © 2014 by the California Department of Conservation California Geological Survey. All rights reserved. No part of this publication may be reproduced without written consent of the California Geological Survey. "The Department of Conservation makes no warranties as to the suitability of this product for any given purpose." Preliminary Geologic Map available from: http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm
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KtcTt
KtcKgdKgb
Tt
Qya
Tt
Qya
Ktc
Ktc
Qa
QoaTt
Qoa
QfKgd
Qyf
Ktc
Kat
Kat
Kat
Kgb
J^m
Kgb
QwJ^m
Ttu
af
Qoa
Ttu
Qoa
QoaJ^m
QoaJ^m
Ttu
Qya
TtuTtu
Qa+Qya
Tt
Qya
Ttl
Ttu
Ttl
Qof J^m
Qya+Qoa
QaTt
Qds
Qvoa QdsQa
Tt
Kgd
Qof
Qp
Qvof
J^m
Kat
Kt
Kat
Kat
Kgd
Qvoa
Kat
Kat
Kt
Qof
Qvof
Kgd
J^m
Qvof
Qls
Tt
Qvof
Qa
Qa
QoaQa
J^m
Kat Ttl
Ttl
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KgdKgd
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Qya
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Qya
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Lancaster
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UD
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Qof
Qof
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Ttl
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Qls?
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Jmg
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Ttl
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J^m
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Qvoa
Qls
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Ktc
Ktc
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GN
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REFERENCES CITEDBull, W.R., 1991, Geomorphic responses to climatic change: New York, Oxford University Press, 326 p.Gastil, G., Girty, G., Wardlaw, M., and Davis, T., 1988, Correlation of Triassic-Jurassic sandstone in peninsular California (abs.):
Geological Society of America Abstracts with Programs, v. 20, no. 3, p. 162.Germinario, M. P. 1982, The depositional and tectonic environments of the Julian Schist, Julian, California: Unpublished M.S. thesis,
San Diego State University, San Diego, California, 95 p.Golz, D.J., Jefferson, G.T., and Kennedy M.P., 1977 , Late Pleistocene vertebrate fossils from the Elsinore Fault Zone. Journal of
Paleontology 51 (4): p. 864-866.Hanley, J.B., 1951, Economic Geology of the Rincon Pegmatites, San Diego County, California: California Division of Mines, Special
Report 7-B, 24 p., scale 1:24,000.Hudson, F.S., 1922, Geology of the Cuyamaca region of California, with special reference to the origin of nickeliferous pyrrhotite:
University of California Publications in Geological Sciences Bulletin, v. 13, p. 175-252.Irwin, W.P., and Greene, R.C., 1970, Studies related to wilderness primitive areas, Agua Tibia, California: U.S. Geological Survey
Bulletin 1319-A, 19 p., scale 1:48,000.Jennings, C. W. and Bryant, W. A., 2010, Fault activity map of California: California Geological Survey Geological Data Map No. 6,
scale 1:750,000.Kennedy, M.P., 1977, Recency and character of faulting along the Elsinore fault zone in southern Riverside County, California:
California Division of Mines and Geology, Special Report 131, 12 p., scale 1:24,000. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm
Kennedy, M. P., 2000a, Geologic map of the Pechanga 7.5' quadrangle, San Diego and Riverside, counties, California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm.
Kennedy, M. P., 2000b, Geologic map of the Pala 7.5' quadrangle, San Diego and Riverside, counties, California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm.
Kennedy, M. P., 2011, Geologic map of the Boucher Hill 7.5' quadrangle, San Diego County California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm.
Larsen, E. S., Jr., 1948, Batholith and associated rocks of Corona, Elsinore and San Luis Rey quadrangles, southern California: Geological Society of America Memoir 29, 182 p., plate 1, scale 1:125,000.
Matti, J. C., Cossette, P.M., and Hirschberg, D.M. , 2010, Classification of surficial materials, Inland Empire Region, southern California: Conceptual and operational framework: U.S. Geological Survey Scientific Investigations Report, in press.
Mann, J.F., 1955, Geology of a portion of the Elsinore Fault Zone California: Division of Mines and Geology Special Report 43, 22 p., scale 1:62,500.
Olmstead, F.H., 1955, Geologic map of La Jolla Indian Reservation, San Diego County, California: Unpublished geologic map, U.S. Geological Survey, Ground Water Branch, Sacramento, California, scale 1:24,000.
Pajak III, A. F., Scott, E., and Bell, C.J., 1996, A review of the biostratigraphy of Pliocene and Pleistocene sediments in the Elsinore Fault Zone, Riverside County, California, in Bell, C.J. and Sumida, S., editors, The uses of vertebrate fossils in biostratigraphic correlation: PaleoBios, v.29, p. 28-49.
Repenning, C.A., 1987, Biochronology of the microtine rodents of the United States, in Woodburne, M.O, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles, University of California Press, p. 236-268.
Reynolds, R.E., and Reynolds, R.L., 1990a, A new late Blancan faunal assemblage from Murrieta, Riverside County, California: San Bernardino County Museum Association Quarterly, v. XXXVVII, p. 34.
_______, 1990b, Irvingtonian? Faunas from the Pauba Formation, Temecula, Riverside County, California: San Bernardino County Museum Association Quarterly, v. XXXVVII, p. 37.
_______, 1993, Rodents and Rabbits from the Temecula Arkose, in Reynolds, R. E. and Reynolds, J., editors, Ashes, faults and basins: San Bernardino County Museum Association Special Publication 93-1, p. 98-100.
Rogers, T.H., 1965, Santa Ana Sheet: California Division of Mines and Geology Geologic Map of California, scale 1:250,000.Sharp, R.V., 1967, San Jacinto fault zone in the Peninsular Ranges of southern California: Geological Society of America Bulletin, v.
78, p. 705-729.Shaw. S.E., Todd, V.R., and Grove, M., 2003, Jurassic peraluminous gneissic granites in the axial zone of the Peninsular Ranges,
southern California, in Johnson, S.E., Paterson, S.R., Fletcher, J.M., Girty, G.H., Kimbrough, D.L., and Martin-Barajas, A., eds., Tectonic evolution of northwestern Mexico and southwestern USA: Boulder, Colorado, Geological Society of America Special Paper 374, p. 157-183.
Streckeisen, A.L., 1973, Plutonic rocks—classification and nomenclature recommended by the IUGS Subcommission on Systematics of Igneous Rocks: Geotimes, v. 18, pp. 26-30.
Tan, S. S., and Kennedy, M. P., 2013, Geologic map of the Aguanga 7.5' quadrangle, San Diego and Riverside, Counties, California: California Geological Survey Preliminary Geologic Map website, http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm.
Todd, V.R., 2013 (in press), Geologic map of the Julian 7.5’ quadrangle, San Diego County, California: U.S. Geological Survey Open-File Report 94-16, scale 1:24,000.
Weber, F.H., Jr., 1963, Geology and mineral resources of San Diego County, California: California Division of Mines and Geology County Report 3, Plate 1, scale 1:120,000.
Woodburne, M. O., 1987, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles University of California Press, 336 p.
GEOLOGIC SUMMARYGeological mapping of the Vail Lake 7.5’ quadrangle was conducted June 2002 - July 2003 and
revised June 2013 by the Department of Conservation, California Geological Survey pursuant to the U.S. Geological Survey STATEMAP cooperative mapping award # 02HQAG0018. The quadrangle lies between 33° 22.5' and 33° 30.0' N. latitude and 116° 52.5' and 117° 00' W. longitude in the northwestern corner of the Borrego Valley 30’x 60’ quadrangle (Fig. 2). The study is aimed at providing new information for use by earth scientist, engineers, planners and developers in decision making related to geologic hazards in the process of long term land use planning.
Structurally the Vail Lake quadrangle lies between the northwest trending, predominately right-slip San Jacinto and the parallel predominately oblique-(up to the north) right-slip Elsinore Fault Zones, two major elements of the San Andreas Fault System (Fig. 3). It is transected by the Agua Caliente Fault Zone which includes from north to south: the Lancaster-Hot Springs, Temecula Creek and Aguanga faults (Fig. 3). These faults are part of a series of faults that lie sub parallel to and splay from the Elsinore Fault Zone between Lake Elsinore and Murrieta (Mann, 1955, Rogers, 1965, Kennedy, 1977). Northeast of Vail Lake the Lancaster-Hot Springs Fault appears to merge with the Murrieta Hot Springs Fault and then with the Wildomar Fault segment of the Elsinore Fault Zone (Kennedy, 1977). The Aguanga and Temecula Creek faults can’t be traced north of Vail Lake and either die out there or step right to the Lancaster-Hot Springs Fault. To the southeast It appears likely that the Lancaster-Hot Springs, Temecula Creek and Aguanga faults merge with the Superstition Mountain, San Felipe and Earthquake Valley faults respectively (Jennings and Bryant, 2010). Based on faulted sedimentary sequences the Agua Caliente Fault Zone has Quaternary elements, however to date there is no evidence of Holocene activity (Jennings and Bryant, 2010).
The Vail Lake quadrangle is divided into two distinctive physiographic provinces by Temecula Creek and the underlying Temecula Creek Fault. Southwest of Temecula Creek lie the steep northeast facing slopes of the Agua Tibia-Palomar Mountain structural block, which rise abruptly from less than 1500’ near Vail Lake to 5077’ at Eagle Crag, a distance of approximately 8 miles. Northeast of Temecula Creek the area is underlain by rolling hills and intermountain valleys that rise and fall from 1500’ at Temecula Creek to over 2000 feet in the northernmost part of the quadrangle, a distance of approximately 3 miles.
The Agua Tibia-Palomar Mountain block is a horst being rapidly elevated by oblique slip between the Elsinore Fault Zone to the southwest and the Temecula Creek and Aguanga faults on the north The rapid uplift is evidenced by the over steepened and deeply dissected Quaternary alluvial fan deposits that mantle the slopes both here and in the adjacent Pechanga, Boucher Hill, and Aguanga quadrangles (Kennedy 2000; Kennedy, 2011; Tan and Kennedy, 2013). The Agua Tibia-Palomar Mountain block is underlain by Mesozoic metamorphic and plutonic rock. The metamorphic rocks are Triassic and Jurassic schist, gneiss and quartzite that have been intruded by Jurassic and Cretaceous plutonic rocks of the Peninsular Ranges batholith (PRB). Within the Vail Lake quadrangle the plutonic rocks include Gabbro of Agua Tibia Mountain and unnamed bodies of granodiorite, tonalite and gabbro.
The rolling hill and intermountain valleys to the northeast of Temecula Creek are underlain by Pliocene and Pleistocene sedimentary rocks composed of locally derived fluviatile detritus and Quaternary unconsolidated alluvium and wash deposits. The Plio-Pleistocene sedimentary succession, which has total combined thickness of less than 1000’ is draped over and in part faulted against a Mesozoic metamorphic and plutonic basement complex. The faulted part is confined to a trough centered near Vail Lake. The trough is defined on its northeastern side by the Hot Springs Fault and on its southwest side by the Aguanga and Temecula Creek faults (Fig. 3). The area has been receiving sediment, since the early Pliocene via Cahuilla and Temecula creeks.
TRIASSIC-JURASSIC METASEDIMENTARY ROCKS:
The Triassic-Jurassic metasedimentary rocks (J^m) consist mostly of quartzofelspathic schist, pelitic schist, quartzite, and metabreccia. These rocks have been informally correlated with the Julian Schist by earlier workers (Hanley, 1951; Olmstead, 1955; Irwin and Greene, 1970). The protolith of the Julian Schist, based on relic depositional structures including graded bedding and Bouma sequences, appears to be a submarine fan sequence (Germinario, 1982). The age of the Julian Schist is considered to be Triassic based on a fossil ammonite (Hudson, 1922). Gastil and others (1988) report a detrital zircon Triassic-Jurassic depositional age for the protolith. The Julian Schist can be no younger than the Middle Jurassic plutonic rocks that intrude it (Shaw and others, 2003). In addition these rocks are similar in composition and metamorphic character to parts of Larsen’s (1948) Bedford Canyon Formation which crops out immediately east of Temecula within the Santa Ana Mountains along the western side of the Elsinore Fault Zone (Kennedy, 1977).
JURASSIC METAGRANITIC ROCKS:
The Jurassic metagranitic rocks (Jmg) are gneissic and composed mostly of dark gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granodiorite. The unit has intruded and assimilated “Julian Schist” and is characterized by elongated remnant inclusions of it. These inclusions range in size from an inch or so to more than 30 feet and have their long axis in the foliation plane. They are tentively correlated with the granodiorite of Harper Creek mapped in the Julian area by Todd (1994). They are described in detail and assigned a Middle Jurassic (U-Pb) age of 170-160 Ma by Shaw and others (2003).
CRETACEOUS GRANITIC ROCKS:
The Cretaceous granitic rocks based on the classification of Streckeisen (1973), see Fig. 3, are mostly tonalite and granodiorite but range in composition from gabbro to monzogranite. They include the tonalite of the Coahuila Valley pluton, (Ktc), the gabbro of Agua Tibia Mountain, (Kat), granodiorite (Kgd), tonalite (Kt), and gabbro (Kgb).
Tonalite of the Cahuilla Valley Pluton (Ktc) crops out in the northeastern part of the quadrangle. It consists mostly of light-gray, coarse-grained, relatively homogeneous hornblende-biotite tonalite. Sphene is a conspicuous accessory mineral occurring as large, honey-colored euhedral crystals. Other accessory minerals include epidote (pistacite and allanite), zircon, apatite, tourmaline, and opaque minerals. These rocks were described in detail by Sharp (1967) and are part of his Cahuilla Valley pluton.
Gabbro of Agua Tibia Mountain (Kat) crops out in the Agua Tibia-Palomar Mountain block. The rock is mostly a dark-gray hornblende gabbro that ranges from medium to coarse grained and is either structureless, foliate, or layered They were correlated with the San Marcos Gabbro of Larsen (1948) by Irwin and Greene (1970). They were later described and mapped as the Gabbro of Agua Tibia Mountain for their unique character and limited outcrop within the Pala and Pechanga quadrangles (Kennedy, 2000a, 2000b).
Granodiorite (Kgd) crops out south of the Temecula Creek Fault and underlies most of the southwestern two thirds of the quadrangle. These rocks were originally described within the Vail Lake quadrangle by Irwin and Greene (1970) and correlated with the Woodson Mountain Granodiorite of Larsen (1948). Rounded masses of light-colored granodiorite are common on ridge crest and slopes, and many of these appear to be residual boulders lying on deeply weathered parent rock. Though they are mostly granodiorite approximately 15 - 20 percent are tonalite and as much as another 5 -10 percent are granite and quartz monzanite. The rock is light-gray to white, coarse- to very coarse-grained hornblende-biotite granodiorite and has a weak foliation marked by the planar oriented biotite.
Tonalite (Kt) crops out in the Agua Tibia Mountains in a less than 1 square mile region along the southwester margin of the quadrangle and in a less than 2 square mile exposure in the southeastern corner of the quadrangle. The rock is typically massive, medium- to coarse-grained, light-gray, hornblende-biotite tonalite and in lesser amounts granodiorite and monzogranite. The contacts between tonalite and granodiorite are gradational and therefore only approximate. In large part these rocks are lithologically similar to and tentatively correlated with rocks 30 miles (50 km) to the southeast within the Julian quadrangle where they were described in detail, assigned a zircon U-Pb isotopic age of 90 – 100 Ma and given the informal name “tonalite of Granite Mountain” (Todd, 2013). Like the Jurassic plutons, they intrude Julian Schist and are locally characterized by remnant inclusions of it.
Gabbro (Kgb) crops out in the northwest corner of the quadrangle approximately 1 mile west of Vail Lake Dam. It is mostly massive, coarse-grained, dark-gray and black, biotite-hornblende-hypersthene gabbro with lesser amount of quartz diorite and tonalite.
PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS:
The Mesozoic basement rocks are overlain by fluviatile, coarse- and medium-grained arkosic sandstone (Temecula Arkose), medium- and fine-grained, fluviatile sandstone and conglomerate (Pauba Formation) and pebble to boulder fan deposits (Dripping Springs Formation).
The Temecula Arkose of Mann, (1955) has been subdivided into two informal parts in this study which include a lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale yellowish-brown, olive-gray dark-yellowish-brown, fine-, medium- and coarse- grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the “upper part” of the formation. Golz and others (1977) reported the exposed thickness of the Temecula Arkose to be approximately 500 m (1640’) to the east in the adjacent Pechanga quadrangle, 125 m (410’) at Vail Lake and 85 m (279’) at Radac. A 1947 wildcat petroleum prospect (Tyrrel #1), located on the northern flank of Temecula Creek approximately 1 mile south east of Vail Lake penetrated 312’ of Temecula Arkose (Mann, 1955. The hills to the north and east of the well are underlain
PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS:
(CONTINUED):
by more than 325’ of Temecula Arkose suggesting that the total combined thickness at Vail Lake is in excess of 600’. The Temecula Arkose has an early Pliocene through late Pliocene age (~ 1.9 – 4.6 Ma) based on fossil vertebrate assemblages from Temecula, Radec, Vail Lake and Butterfield Valley (Golz and others, 1977; Kennedy, 1977; Reynolds and Reynolds, 1993; Pajak and others, 1996). Kennedy (1977) assigned the unit a late Pliocene Blancan 1V-V mammal age (2.2 to 2.8 Ma) based on vertebrate assemblages collected east of the quadrangle. Assemblages include Nannippus, Hypolagus, Tetrameryx, Equus, and Odocoileus (Golz and others, 1977). Later work established the first occurrence of Tetrameryx as Irvingtoninan 1 rather than late Blancan (Woodburne, 1987), placing the Temecula Arkose age nearer 1.9 Ma than 2.2 Ma. In addition, a microtine fauna from this unit in the Radec area was reported to have an age of 4.6 Ma (Blancan 1) (Repenning, 1987) which would suggest a depositional period that extended from early Pliocene into the lower Pleistocene.
The Pauba Formation of Mann, (1955) is moderate- yellowish-brown, poorly-consolidated, cross-bedded, medium- and coarse-grained sandstone, and cobble conglomerate. First described in print by Mann (1955) and later by Kennedy (1977) for exposures at Rancho Pauba located about 5 km southeast of Temecula. A vertebrate fauna from the Pauba Formation is reported to be of late Irvingtonian and early Rancholabrean Land Mammal Age (Reynolds and Reynolds, 1990a; 1990b), however, the Rancholabrean age is in question (Pajak, and others, 1996).
The Dripping Springs Formation of Mann, (1955) is light-brown, poorly- consolidated, pebble, cobble and boulder fanglomerate. First described by Mann (1955) and later by Kennedy (1977) for exposures south of Highway 79 along the eastern margin of the map in the Dripping Springs corridor. It is considered to be equivalent to the old and very old alluvial fan deposits of the area (middle to early Pleistocene).
QUATERNARY SURFICIAL DEPOSITS:
The surficial Quaternary sedimentary deposits of the area include alluvial wash, fan, and valley fill, The alluvial fan deposits are those deposited in fans along the mountain fronts. The alluvial flood plain deposits are those deposited in flood plains in the valley floors. The classification of the surficial Quaternary sedimentary deposits is modified from the U.S. Geological Survey, Classification of surficial materials, inland empire region, southern California: Conceptual and operational framework, described by Matti and others (2010). Inherent to this classification is the fact that the surficial deposits have been deposited continuously, albeit at different rates, throughout the Quaternary Period and each of the four basic lithostratigaphic units mapped (alluvial wash, fan and alluvial valley fill deposits) represent often interfingered time transgressive facies. The parameters used in this modified classification include: 1) physical properties and lithologic features, e.g. consolidation, induration, fabric, grain size, sorting, etc., 2) genesis and geomorphic setting, e.g. alluvial fan, alluvial valley fill and alluvial wash deposits) and 3) age determinations, e.g. radiometric analyses, paleontology, pedogenic soil characteristics, desert varnish, vegetation, degree of incision, etc.
SURFICIAL QUATERNARY UNITS INCLUDE:
1). “Modern surficial deposits” which are those being deposited actively or intermittently active over the past few hundred years. Their soil development is slight to non-existent. They are labeled Qw, Qf and Qa (alluvial wash, alluvial fan and alluvial valley fill deposits). 2). “Young surficial deposits” which are those that were deposited during the Holocene and latest Pleistocene or since the Holocene-to-Pleistocene climatic transition (Bull, 1991). They are slightly dissected, have slight soil development, and little if any pavement or varnish. They are labeled Qyf and Qya (young alluvial fan and young alluvial valley fill deposits). 3). “Old surficial deposits” which are those that were deposited during the middle to late Pleistocene and spanning the period of approximately 500ka to about 15ka. They have moderately dissected surfaces, good soil development, minor clay films, and moderate varnish and pavement. They are labeled Qof and Qoa (old alluvial fan and old alluvial valley fill deposits).4). “Very old surficial deposits” which are those that were deposited during the early to middle Pleistocene or approximately 1 Ma to 500ka. They have well dissected surfaces, strong soil development, thick clay films and well developed varnish and pavement. They are labeled Qvof and Qvoa (very old alluvial fan and very old alluvial valley fill deposits).
QUATERNARY LANDSLIDE DEPOSITS:
Highly fragmented to largely coherent landslide deposits. Unconsolidated to consolidated. Most mapped landslides contain scarp area as well as slide deposit. Most reactivated in part during Holocene. Question mark indicates that the landslide is questionable.
ACKNOWLEDGEMENT OF PREVIOUS GEOLOGIC MAPPING:
Bedrock contacts and faults in the mountainous southwestern half of the quadrangle are modified from Weber (1963), Rogers (1965) and Irwin and Greene (1970). Geological mapping within the sedimentary succession in the vicinity of Vail Lake by J. F. Mann (1955) proved very useful in developing a better understanding of the Plio-Pleistocene stratigraphy of the area. Modifications of all earlier work was based on new mapping and observations made from large scale stereo air photography including USDA 1953 (scale 1:24,000) and Riverside County, 1990 (scale 1:24,000) as well as from Google Earth imagery.
Figure 3 - Map showing the location of the Vail Lake, Aguanga Palomar Observatory and Boucher Hill 7.5’ quadrangles with respect to the Elsinore, Agua Caliente and San Jacinto fault zones.
EXPLANATIONFault-- dashed where inferred
116° 15'
33° 30'
33° 15'
116° 15'117° 00'
33° 15'
33° 30'
117° 00'
Aguanga 7.5' quadrangle
Palomar Obs. 7.5' quadrangle
Vail Lake 7.5' quadrangle
Boucher Hill 7.5' quadrangle
San
Jacinto
FaultZone
Hot Springs
Fault
Temecula
Creek
Fault
Agua Tibia- Palomar Mt. Block
Fault
Zone
Lake Henshaw
Elsinore
Murrieta Hot Springs-Lancaster-
Agua
Caliente
Fault
Zone
Vail Lake Trough
Aguanga
Fault
Borrego Valley 1:100,000-scale Quadrangle
Miles0 10 20 30
Aguanga Beauty Mt. Bucksnort Mt. Collins Valley Clark Lake Rabbit Pk. Oasis
Boucher Hill PalomarObservatory
Borrego Springs Hot Springs Mt. Borrego Palm Canyon
Clark Lake Fonts Point SeventeenPalms
Rodriquez Mt. Mesa Grande Warners Ranch Ranchita Tubb Canyon Borrego Sink Borrego Mt. Shell Reef
Ramona Santa Ysabel Julian EarthquakeValley
Whale Peak Harper Canyon Borrego Mt. S.E.
Vail Lake
Figure 2 - Index map showing the location of the Vail Lake and other 7.5' quadrangles in the Borrego Valley 1:100,000-scale quadrangle.
CGS
OFR 96-06
&
CD 2000
-008
San Pasqual
FY 2002-03 FY 2005-06 FY 2006-07
Mapping completed under STATEMAP
Revised 2011
Revised 2013Revised 2013
N
MAP SYMBOLS
UD
Contact - Contact between geologic units; dashed where approximately located; dotted where concealed.
Fault - Solid where accurately located; dashed where approximately located; dotted where concealed. U = upthrown block, D = downthrown block. Arrow and number indicate direction and angle of dip of fault plane, queried where uncertain.
Anticline - Solid where accurately located; dashed where approximately located; dotted where concealed. Single arrow indicates direction of plunge.
Syncline - Solid where accurately located; dashed where approximately located; dotted where concealed. Single arrow indicates direction of plunge.
Landslide—Arrows indicate principal direction of movement. Queried where existence is questionable.
Strike and dip of sedimentary beds
Strike and dip of metamorphic foliation
Inclined
Vertical
Strike and dip of joints
Inclined
Vertical
55
5
70
Qls?
55
?
Qw Qf Qaaf
Qya
Qoa
Qa+Qya
Qyf
Qof
Qya+Qoa
Qvof Qvoa
Qls
TtTtu
Ttl
QpQds
KgdKatKtc Kt Kgb
JmgJ^m
JURASSIC
CENOZOIC
MESOZOIC
Holocene
Pleistocene
Pliocene
QUATERNARY
TERTIARY
CRETACEOUS
TRIASSIC
CORRELATION OF MAP UNITS
QuartzSyenite
QuartzMonzonite
QuartzMonzodiorite
Syenite Monzonite Monzodiorite
Granite
Alka
li-feld
spar
Gra
nite
Tonalite
Diorite
Syen
ogra
nite
Granodiorite
Mon
zogr
anite
Quartz
Diorite
90 65 35 10
5
20
60Q Q
A P
60
20
5
60
Figure 1 - Classification of plutonic rock types (Streckeisen, 1973).A - alkali feldspar; P - plagioclase feldspar; Q - quartz.
MODERN SURFICIAL DEPOSITSSediment that has been recently transported and deposited in channel and washes, on surfaces of
alluvial fans and alluvial plains, and on hill slopes and in artificial fills. Soil-profile development is non-existant. Includes:
Artificial fill (late Holocene)—Compacted manmade fill deposits adjacent to Vail Lake spillway.
Wash deposits (late Holocene)—Unconsolidated bouldery to sandy alluvium of active and recently active washes.
Alluvial fan deposits (late Holocene)—Active and recently active alluvial fans. Consists of unconsolidated, bouldery, cobbley, gravelly, sandy, or silty alluvial fan deposits, and headward channel parts of alluvial fans. Trunk drainages and proximal parts of fans contain greater percentage of coarse-grained sediment than distal parts.
Alluvial flood plain deposits (late Holocene)—Active and recently active alluvial deposits along canyon floors. Consists of unconsolidated sandy, silty, or clay-bearing alluvium. Does not include alluvial fan deposits at distal ends of channels.
YOUNG SURFICIAL DEPOSITSSedimentary units that are slightly consolidated to cemented and slightly to moderately dissected.
Alluvial fan deposits typically have high coarse-fine clast ratios. Young surficial units have upper surfaces that are capped by slight to moderately developed pedogenic-soil profiles. Includes:
Young alluvial fan deposits (Holocene and late Pleistocene)—Mostly poorly- consolidated and poorly-sorted sand, gravel, cobble and boulder alluvial fan deposits.
Young alluvial flood plain deposits (Holocene and late Pleistocene)—Mostly poorly-consolidated, poorly-sorted, permeable flood plain deposits.
MODERN AND YOUNG SURFICIAL DEPOSITS UNDIVIDED
Active alluvial flood plain and young alluvial flood plain deposits undivided (late Holocene and Pleistocene)—See descriptions of individual deposits.
OLD SURFICIAL DEPOSITSSediments that are moderately consolidated and slightly to moderately dissected. Older surficial
deposits have upper surfaces that are capped by moderate to well-developed pedogenic soils. Includes:
Old alluvial fan deposits (late to middle Pleistocene)—Reddish-brown, gravel and sand alluvial fan deposits that are usually indurated and slightly dissected.
Old alluvial flood plain deposits undivided (late to middle Pleistocene)—Fluvial sediments deposited on canyon floors. Consists of moderately well consolidated, poorly-sorted, permeable, commonly slightly dissected gravel, sand, silt, and clay-bearing alluvium.
YOUNG AND OLD SURFICIAL DEPOSITS UNDIVIDED
Young alluvial flood plain deposits and old alluvial flood plain deposits undivided (Holocene and late to middle Pleistocene)—See descriptions of individual deposits.
VERY OLD SURFICIAL UNITSSediments that are slightly to well consolidated to indurated, and moderately to well dissected, Upper
surfaces are capped by moderate to well-developed pedogenic soils. Includes:
Very old alluvial fan deposits (middle to early Pleistocene)—Mostly well-dissected, well-indurated, reddish-brown sand and gravel alluvial fan deposits.
Very old alluvial flood plain deposits (middle to early Pleistocene)—Fluvial sediments deposited on canyon floors. Consists of moderately to well-indurated, reddish-brown, mostly very dissected gravel, sand, silt, and clay-bearing alluvium.
Landslide deposits (Holocene to Pleistocene)—Highly fragmented to largely coherent landslide deposits. Unconsolidated to consolidated. Most mapped landslides contain scarp area as well as slide deposit. Question mark indicates that the landslide is questionable.
SEDIMENTARY ROCKS
Dripping Springs Formation (early to late Pleistocene)—Light-brown, poorly- consolidated, pebble, cobble and boulder fanglomerate. Equivalent to Qof. See description in Geologic Summary for more detail.
Pauba Formation (early to late Pleistocene)—Moderate-yellowish-brown, poorly-consolidated, cross-bedded, medium- and coarse-grained sandstone, and cobble conglomerate. See description in Geologic Summary for more detail.
Temecula Arkose (early to late Pliocene)—The Temecula Arkose is here subdivided into two informal parts. A lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale yellowish-brown, olive-gray dark yellowish-brown, fine-, medium- and coarse-grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the "upper part" of the formation. See description in Geologic Summary for more detail.
PLUTONIC ROCKS (See Figure 1 for classification).
Tonalite of the Cahuilla Valley Pluton (mid-Cretaceous)—Light-gray, coarse-grained, relatively homogeneous hornblende-biotite tonalite.
Gabbro of Agua Tibia Mountain (mid-Cretaceous)—Dark-gray hornblende gabbro that ranges from medium- to coarse-grained and is structureless, foliate, or layered.
Granodiorite (mid-Cretaceous)—Light-gray to white, coarse- to very coarse-grained hornblende-biotite granodiorite. It has a weak foliation marked by the planar oriented biotite.
Tonalite (mid-Cretaceous)—Light-gray, massive, medium- to coarse-grained, hornblende-biotite tonalite.
Gabbro (mid-Cretaceous)—Dark-gray and black, massive, coarse-grained, biotite-hornblende-hypersthene gabbro with lesser amounts of quartz diorite and tonalite.
METAMORPHIC ROCKS
Metagranitic rocks (Jurassic)—Mostly dark-gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granite.
Metasedimentary rocks (Jurassic and Triassic)—Mostly quartzofeldspathic schist, pelitic schist, quartzite, and metabreccia.
DESCRIPTION OF MAP UNITS
Qw
Qf
Qa
af
Qya
Qoa
Qvof
Qvoa
Qls
Kgd
Kat
Ktc
Kt
Kgb
Qa+Qya
Jmg
TtTtu
Ttl
J^m
Qof
Qyf
Qp
Qds
Qya+Qoa
CGSSGSAM PSUC
Coordinate System:Universal Transverse Mercator, Zone 11N,North American Datum 1927.
Topographic base from U.S. Geological SurveyVail Lake 7.5-minute Quadrangle, 1953 (Photorevised 1988).
This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP Award no. 02HQAG0018
116°52'30''33°30'
Prepared in cooperation with the U.S. Geological Survey, Southern California Areal Mapping Project
116°45’33°30'
33°22'30”116°52'30''
33°22'30”116°45’
STATE OF CALIFORNIA – EDMUND G. BROWN JR., GOVERNORTHE NATURAL RESOURCES AGENCY – JOHN LAIRD, SECRETARY FOR NATURAL RESOURCES
DEPARTMENT OF CONSERVATION – MARK NECHODOM, CONSERVATION DIRECTOR CALIFORNIA GEOLOGICAL SURVEYJOHN G. PARRISH, Ph.D., STATE GEOLOGIST PRELIMINARY GEOLOGIC MAP OF THE VAIL LAKE 7.5’ QUADRANGLE, CALIFORNIA
PRELIMINARY GEOLOGIC MAP OF THE VAIL LAKE 7.5' QUADRANGLE,SAN DIEGO AND RIVERSIDE COUNTIES, CALIFORNIA: A DIGITAL DATABASE
Version 1.1By
Michael P. Kennedy1
2003(Revised 2014)
Digital Preparation byMatt D. O’Neal2, Carlos I. Gutierrez2 and Apri Mertz3
1. California Geological Survey, 888 South Figueroa Street, Suite 475, Los Angeles, CA 900172. California Geological Survey, 801 K Street, MS 12-32, Sacramento, CA 95814
3. U.S. Geological Survey, Department of Earth Sciences, University of California, Riverside
Copyright © 2014 by the California Department of ConservationCalifornia Geological Survey. All rights reserved. No part ofthis publication may be reproduced without written consent of theCalifornia Geological Survey.
"The Department of Conservation makes no warranties as to thesuitability of this product for any given purpose."
Preliminary Geologic Map available from:http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm
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