Geotectonic evolution of lunar LQ-4 region based on ... · Research paper Geotectonic evolution of lunar LQ-4 region based on multisource data Jianping Chena,b,*, Yanbo Xuc, Xiang

Geoscience Frontiers 5 (2014) 227e235

Contents lists available at SciVerse ScienceDirect

China University of Geosciences (Beijing)

Geoscience Frontiers

journal homepage: www.elsevier .com/locate/gsf

Research paper

Geotectonic evolution of lunar LQ-4 region based on multisource data

Jianping Chen a,b,*, Yanbo Xu c, Xiang Wang d, Shujun He a,b, Danping Yan a, Shaofeng Liu a,Yongliao Zou c, Yongchun Zheng e

a School of Earth Sciences and Resources, China University of Geosciences (Beijing), 29 Xueyuan Road, Beijing 100083, Chinab The Institute of High and New Techniques Applied to Land Resources, China University of Geosciences (Beijing), Beijing 100083, Chinac Shandong Gold Geology and Mineral Exploration Co., Ltd., Laizhou 261400, ChinadDevelopment Research Center, China Geological Survey, Beijing 100037, ChinaeCAS National Astronomical Observatories, Beijing 100012, China

a r t i c l e i n f o

Article history:Received 17 October 2012Received in revised form17 May 2013Accepted 27 May 2013Available online 25 June 2013

Keywords:LunarTectonic elementsTectonic unitsEvolutionLQ-4 region

* Corresponding author. Tel.: þ86 13910802638.E-mail address: [email protected] (J. Chen).

Peer-review under responsibility of China University

Production and hosting by Els

1674-9871/$ e see front matter � 2013, China Univerhttp://dx.doi.org/10.1016/j.gsf.2013.05.006

a b s t r a c t

The Sinus Iridum region, the first choice for China’s “Lunar Exploration Project” is located at the center ofthe lunar LQ-4 area and is the site of Chang’e-3 (CE-3)’s soft landing. To make the scientific exploration ofChang’e-3 more targeted and scientific, and to obtain a better macro-level understanding of thegeotectonic environment of the Sinus Iridum region, the tectonic elements in LQ-4 region have beenstudied and the typical structures were analyzed statistically using data from CE-1, Clementine, LRO andLunar Prospector missions. Also, the mineral components and periods of mare basalt activities in thestudy area have been ascertained. The present study divides the tectonic units and establishes the majortectonic events and sequence of evolution in the study area based on morphology, mineral constituents,and tectonic element distribution.

� 2013, China University of Geosciences (Beijing) and Peking University. Production and hosting byElsevier B.V. All rights reserved.

1. Introduction

While China is a late entrant in lunar exploration, the successfullaunch and data acquisition of CE-1 signaled a further step intolunar science and offered proprietary first-hand data for ongoinglunar science research in the country. The Sinus Iridum region, thefirst choice for China’s ‘Lunar Exploration Project’, is located at thecenter of the lunar LQ-4 area and is the site of Chang’e-3 (CE-3)’ssoft landing. LQ-4 area is thus selected as the study area to obtainan overall understanding of the geologic and tectonic environmentof the Sinus Iridum region, which might make the scientificexploration of CE-3 more targeted and scientific.

Though the Moon has been studied for decades, with consid-erable progress made in the research on material composition,

of Geosciences (Beijing)

evier

sity of Geosciences (Beijing) and P

gravity andmorphology, its geological conditions and evolution arestill poorly understood. The macro-tectonic theory of the Moon hasgone through several cycles. When the geosynclines-platformtheory was prevailing, the lunar tectonic outline units had beendelineated in accordance with it, whereas the lunar tectonic divi-sion of units was made according to the terrane blocks when theplate tectonics theory was prevalent. In 1969, a tectonic map of theMoon was compiled by Kozlov and Sulidi-Kondratiev (1969).Raitala (1978) studied the structural domain near Mare Humorumat the southwest of the Oceanus Procellarum, and inferred the re-gion’s geological activity based on seismic data. Though there aregreat methodological differences in the research into Earth andplanetary geology, knowledge about planetary surface structurehelps in understanding planetary evolution and their overall tec-tonic framework. Surface structural research of the Moon willdefinitely aid in the study of lunar geological conditions.

2. Regional geology

The lunar LQ-4 region is located in the lunar nearside mare areabetween 30� and 65�N, 0� and 60�W, and mainly consists of thenortheast part of Oceanus Procellarum, the most of Mare Frigorisand northern highlands, and the most of Mare Imbrium (Fig. 1).

eking University. Production and hosting by Elsevier B.V. All rights reserved.

Figure 1. Selenographic location of LQ-4 region (the base map is of CE-1 CCD stereo camera image 2c data).

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235228

Rocks in this region typically include the mare basalt, highlandanorthosite, KREEP rock and impact melt breccias, with mare basaltoccupying about 70% of the area. This area was highly exposed toimpacts in the early history of the Moon and to intensive basaltactivity in the later periods (Wilhelms andMcCauley,1971; Melosh,1977;Wilhelms,1987). As a region located inside the KREEP terraneof Oceanus Procellarum, it plays a significant role in the research onthe formation and evolution of KREEP terrane (Jolliff et al., 2000).

2.1. Image features interpretation

As indicated in the image synthesized from the data obtainedfrom the CE-1 CCD stereo camera image 2c (Fig. 2), the region iscomposed of two subregions with noticeable albedo difference: ahighland anorthosite region with high albedo and rough surface,and a mare basalt regionwith very low albedo and smooth surface.The highland anorthosite is mainly found in the central andnorthern part of the map, i.e., the northern crater area of MareImbrium and the northern highland area of Oceanus Procellarum;while the mare basalt is mainly found in Mare Imbrium, OceanusProcellarum, Mare Frigoris areas and in Sinus Iridum and PlatoCrater.

2.2. Topography and geomorphology

The DEM shows the topography and geomorphology of the re-gion: higher-altitude areas are mostly found in the area north ofMare Imbrium, typically the surrounding mountains of Sinus Iri-dum and Plato Crater, and the highland area north to OceanusProcellarum, with altitude up to 1000 m and the mountains sur-rounding three large impact craters (Babbage, J. Herschel and SouthCraters), which are too old and thus are largely degraded to beidentified directly in the image (Fig. 2). Lower-altitude areas aremostly found in Mare Imbrium, Oceanus Procellarum area andMare Frigoris area, and the topography in Mare Imbrium graduallysmoothens from south to north (Fig. 3). The topography agreesspatially with the features identified from the CCD remote-sensedimages.

2.3. Mineral and rock composition

2.3.1. TiO2 content and distributionExcept for the uniformly distributed volatiles in lunar maria,

mare basalt varies significantly in chemical composition, and thesedifferences help distinguish different types of basalt. Ti, forexample, is an important parameter for classifying basalt types(Charette et al., 1974; BVSP, 1981; Papike et al., 1991; Taylor et al.,

1991; Neal and Taylor, 1992). Fig. 4a shows the TiO2 content andits distribution extracted from CE-1 IIM data. It indicates that thehighland area has lower TiO2 content (<2%), whereas the TiO2content in the mare area varies considerably and is notably higherthan that in the highland area; higher TiO2 areas are mostly locatedto the west of Mare Imbrium and part of Oceanus Procellarum nearthe Mare Imbrium, while lower TiO2 content is found to thenortheast of Mare Imbrium, inside Sinus Iridum and in MareFrigoris.

2.3.2. FeO content and distributionFe is the basic element for understanding and classifying

igneous rocks and one of the chemical elements contained in mostsilicate minerals on the Moon. Obtaining the content and distri-bution of Fe will improve our understanding of the origin andevolution of the Moon (Taylor, 1975; Lucey et al., 1995; Lawrenceet al., 1998, 2000). Fig. 4b shows the FeO content and distributionextracted from CE-1 IIM data, it indicates that the FeO content inthe mare area is significantly higher than that in the highlands, andthe regions with higher TiO2 (wt.%) within the mare also containhigh values of FeO, suggesting a positive correlation between them.

2.3.3. Pyroxene content and distributionPyroxene is the main mineral of mare basalts and helps distin-

guish mare basalt from highland anorthosite as a supplementaryparameter. Fig. 4c shows the pyroxene content and distributionextracted from CE-1 IIM data. It indicates that the higher pyroxeneareas are mostly found in Mare Imbrium, Oceanus Procellarum andMare Frigoris, whereas the pyroxene content in the highlands areais very low, suggesting positive correlation between the pyroxenecontent and distribution and TiO2/FeO.

2.3.4. Al2O3 and plagioclase content and distributionPlagioclase is the main mineral of highland anorthosite. Al2O3 is

the main chemical component of plagioclase and it helps in dis-tinguishing highland anorthosite from mare basalt. Fig. 4d,eshows the Al2O3 and plagioclase content and distribution, and in-dicates that the higher Al2O3 and plagioclase areas aremostly foundin the highlands area, while the content is very low in MareImbrium, Oceanus Procellarum and Mare Frigoris, suggesting pos-itive correlation between Al2O3 and plagioclase content, andnegative correlation with TiO2/FeO and the pyroxene content anddistribution.

2.3.5. Th content and distributionTh is not only one of the most essential elements for investi-

gating the Moon and the evolution of the lunar surface (Lawrence

Figure 2. CE-1 CCD image of LQ-4 region (synthesized from CE-1 CCD image 2c data, 120 m resolution).

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235 229

et al., 1998, 2000), but also is important in further understandingthe formation and evolution of KREEP rock through studies of itsglobal distribution, as Th is enriched in the rock. KREEP terrane ofOceanus Procellarum is famous for containing high Th (Jolliff et al.,2000). Th is well correlated to REE and, more importantly, Sm andGa are also well correlated to Th (Ouyang, 1988; Taylor et al., 1991).The Th content is an important measure for subdividing tectonicstructures. In this region, Th content ranges from 2.2 to 13 ppm andthe average value is 5 ppm. The highest Th (w13 ppm) area isAristillus, near the Aristarchus Impact Craters (Fig. 4f).

Figure 3. Geomorphic map of LQ-4 region (produced with LRO la

2.3.6. False color composite image“Standard Galileo color composite” which typically involves

false color composite bywave band ratios was used by the scientificteam in the Galileo lunar exploration to identify the petrologicdifferences on the lunar surface (Belton et al., 1994). This techniquehas also beenwidely applied to Clementine UV-VISmulti-band datato identify the main rock types (Bugiolacchi and Guest, 2008;Kramer et al., 2008; Hackwill, 2010). The three band ratios effec-tively reveal the material features of the lunar surface. Fig. 4gclearly shows material units of different compositions: the blue

ser altimeter (LOLA), with spatial resolution of up to 60 m).

Figure 4. Mineral and rock components in LQ-4 region. a: TiO2 content and distribution map (based on CE-1 IIM data); b: FeO content and distribution map (based on CE-1 IIMdata); c: Pyroxene distribution map (based on CE-1 IIM data); d: Al2O3 distribution map (based on CE-1 IIM data); e: Plagioclase distribution map (based on CE-1 IIM data); f: Thcontent distribution map (based on LP GRS data); g: False color composite image (based on Clementine UV-VIS band ratio data).

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235230

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235 231

areas are typically high-Ti areas; the orange and yellow areas arelow-Ti basalt areas, while the red areas are typically mature anor-thosite highlands with presence of comparatively fresh bluishimpact craters (Pieters et al., 1994). The petrologic areas agree withthe Ti and Fe content indicated in Fig. 4a,b.

3. Tectonic element interpretation and basalt activity

Tectonic elements in the region include linear structures, ringstructures, terrane structures and basin structures. The whole re-gion is within the KREEP terrane of Oceanus Procellarum and is notsubdivided further. The region was subject to intense magmaticactivity when a number of basalt infill events occurred (Hiesingeret al., 2000).

3.1. Interpretation of linear structures

The linear structures in LQ-4 region were interpreted accordingto the features and identification signs of the linear structures withthe data from CE-1, Clementine, LRO and Lunar Prospector missionsand 10 types of linear structures were figured out: mare ridges,lunar rima, grabens, valleys, ruptures, pit chains, mountains, scarps,collapses and other linear structures as presented in Fig. 5.

Lunar ridges are one of the typical linear structures on the lunarsurface. From the interpretation results, it is obvious that many lunarridges appear in the mare basalt areas. Statistically, lunar ridges areof the most numerous among the linear structures and have their

Figure 5. Tectonic ma

widest distribution in LQ-4. They are mostly found in mare areasincluding Mare Imbrium, Oceanus Procellarum and Mare Frigoris, inconcentric arcs inside Mare Imbrium, and in (sub)radial forms inOceanus Procellarum and Mare Frigoris (Yingst and Gregg, 2009).

Large mountains are considered to be another typical linearstructure. Physiographically, the mountains are related to large,direct aerolite impact, of different scales, or mostly result fromstructural or tectonic activities. They can be reformed by isostasy inthe later periods.

The collapse structures occur in cascades on the inner wall oflarge impact craters or basin craters, e.g., Sinus Iridum, Plato Craterand Archimedes Crater and contain noticeable steep slide surfacesand slump masses. These are mostly the result of gravitationalslope processes. Other types of linear structures are only found inlimited cases.

3.2. Interpretation of ring structures

The most typical ring structures on the lunar surface are theimpact craters of different sizes ranging from below meter scale tolarge impact basins. The interpretation of the ring structures ispresented in Fig. 5. Large diameter impact craters mostly occur inthe highlands areas, while smaller impact craters occur in the marebasalt unit. From the top left of Fig. 5, a few larger old impact craterscan be interpreted and inferred by their existing shapes as Nec-tarian or Prenectarian craters, which are typical of large old craters.J. Herschel Crater (62�N, 42�W, dia. 165 km), Babbage Crater

p of LQ-4 region.

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235232

(59.7�N, 57.1�W, dia. 143 km) and South Crater (58�N, 50.8�W, dia.104 km) are examples, and have extremely altered the topographyand geomorphology of the tectonic units and whose own geo-morphology in turn has been severely altered by weathering anderosion in the later periods. For example, they were overlaid bymaterial excavated from Mare Imbrium events (Fra Mauro forma-tion), making it impossible to identify them directly from remote-sensing images rather than from DEM data.

Many residual impact craters that are overlaid by later basaltand whose peripheral craters outcrop above the basalt can beidentified in LQ-4 region on the periphery of Mare Imbrium basincrater and at the interface between Mare Frigoris and OceanusProcellarum, suggesting that the basalt thickness is quite limited inthis region.

In Fig. 5, thedistributionof the impact craters in thehighlandsareaare obviously denser than those in the mare area and there are morelarger-diameter craters in the highlands area. These craters becomemore complex with size. Craters of more than 20 km in diametergenerally have more complete crater structure like the bottom, wall,lip and rim, with sputteringmatters (rays) if formed in later eras, andsome have a central peak (Michael and Neukum, 2001; Kneissl, et al.,2010). Somecraters including Sinus Iridum ImpactCrater, Plato Craterand Archimedes Crater were filled with mare basalt.

Of the ring structures of LQ-4 region, the mare domes and vol-canic craters are typically located in the Rümker area (40.8�N,58.1�W) on the mare platform (plateau), with domes occurring ingroups and with a gentle topography. Small volcanic craters areseen in the center of some of the domes, suggesting that this regionwas subjected to volcanic activities and is an important area forinvestigation of such activities. The active period is equivalent tothe infill period of mare basalt. There might be a certain relationbetween such volcanic activities and the infill manner of the broadmare basalt.

Figure 6. Linear structures vs. free air gravity anomaly in LQ-4 region (Source: USGS PDS Clespheric harmonic gravity model GLGM-2, with spatial resolution of 0.25� � 0.25�) (Zuber e

Regarding basin structures, LQ-4 was obviously subjected to basintectonics. Part of the boundary of Mare Imbrium basin is roughlydelineated according to the geomorphology and chemical composi-tionof the region. Since thestudyarea is located inside the largebasinsof Oceanus Procellarum, its boundary is not included in the study.

3.3. Basalt activities

The basalt infill activities are an important geologic event in LQ-4.The basalt filled up the basins of Mare Imbrium, in Oceanus Procella-rum andMare Frigoris. The basalt infill took place inmultiple periods,and the magma components also show certain rules of variation(Hiesinger et al., 2000, 2003, 2010;Neukum, 2001;Xuet al., 2012). Thebasalt outcrop in the region typically occurs in late Imbrian to Era-toshenian, and can be divided by TiO2 content in the basalt as: high-Tibasalt (TiO2 � 7.5%), moderate-Ti basalt (4.5e7.5%) and low-Ti basaltunits (TiO2 < 4.5%) (Giguere et al., 2000). The moderate- and high-Timare basalts in the region mostly occur in the western half of MareImbrium basin while the low-Ti mare basalt mostly occurs in thenortheasternparts of theMare Imbriumbasin, in Sinus Iridum, inPlatoImpact Crater, in Mare Frigoris and the other areas of Oceanus Pro-cellarum (Fig. 5). Calculation of the surface age of the mare basalt re-veals that younger the basalt richer the Fe and Ti content. Similarvolcanic groups or mare domes occur in Rümker area of OceanusProcellarum, with accumulated volcano features, lava caps and vol-canic clasts (Glass, 1986).

4. Discussion

4.1. Interaction of tectonic elements

Mare ridges in lunar mares are relatively young linear structuresthat are mostly formed after the emplacement of mare basalt. Some

mentine data 1996) (Free air gravity data derived from Clementine data after 70-ordert al., 1994).

Table 1Division of the tectonic units in the LQ-4 region.

I. Primary tectonicunit

II. Secondary tectonic unit III. Tertiary tectonic unit

Mare tectonic unit Mare Imbrium basintectonic unit

Mare Imbrium centertectonic unitMare Imbrium edgetectonic unitMare Imbrium basincrater tectonic unit

Oceanus Proellarum-MareFrigoris mare-like basintectonic unit

e

Terra tectonic unit Northern terra tectonic unit e

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235 233

very small impact craters were incised by lunar ridges, suggestingthe ridges’ were active in recent eras (Sharpton and Head, 1988;Watters et al., 2010).

Theories for the explanation of the genesis of the lunar ridgesare mostly concentrated on volcanism (Strom, 1964, 1972; Hodges,1973; Golombek et al., 1991), tectonism (Bryan, 1973; Muehlberger,1974; Maxwell et al., 1975; Lucchitta, 1976,1977; Schultz, 2000) andmixed volcanic-tectonic mechanisms (Scott et al., 1975; Yue et al.,2007), though recently attention has focused on the relation be-tween reverse faults and lunar surface anticlines in connectionwiththe tectonic genesis theory. Some researchers believe the lunarridges to be anticlinal folds of reverse faults below the lunar sur-face, indicating the intensity of extrusion stress (Schultz, 2000;Thomas, 2010; Wei et al., 2012).

Statistical analysis of the orientation of lunar ridges in LQ-4region reveals that they are mostly oriented in the NS, NE or NWdirection with none in the EW direction, which agrees with thepreferential direction of the global grid predicted earlier. Lunarridges in this region typically have two parts. One part is distributedaround the edge of basins including Mare Imbrium and is primarilysubject to basin subsidence, with the distribution possibly subjectto the basement shape of the basin (Waskom, 1975); while lunarridges extending in the near-NW direction in the center of MareImbrium are distributed nearly identically to those in OceanusProcellarum and Mare Frigoris. This indicates that the maximumtectonic stress should be in the EW direction, nearly perpendicularto the orientation of the lunar ridges and its source of power shouldrelate to regional stress, like tidal forces and thermal contraction(Bryan, 1973; Fagin et al., 1978; Schultz, 2000; Wei et al., 2012).

Mare Imbrium basin is a typical mascon basin, and no consensushas been reached on how mascons have formed (Potts and vonFrese, 2003; Ouyang, 2005). It reflects the thickness of the deepstructures and basalt in the basin. The most noticeable feature ofFig. 6 is the control exerted by the basin structures, especially in

Figure 7. Tectonic style of

Mare Imbrium, over the lunar ridges extending in concentric rings.Their extension has typically resulted from the control of thebasement shape of the basin which has been driven by basin sub-sidence. Similarly, the lunar ridges extending in concentric ringswithin the Mare Imbrium basin are also located in the positiveenegative anomaly transition zone. This suggests changes in thebasement shape of the basin, including transition of the basin edgetoward the basin center and the increasing thickness of mare basalt,which is further indication of the thin crust at the center and theover-compensation of materials at depth in the Mare Imbriumbasin.

4.2. Interaction between tectonic units and different tectonicelements

Tectonic units not only reflect the main tectonic framework in aregion, but also reveal the relation between them and the differenttectonic elements in a more direct way. Table 1 and Fig. 5 show thetectonic units in LQ-4 divided according to geomorphology, rock/mineral composition and tectonic element distribution.

As indicated in Fig. 5, the impact craters of the ring structuresmostly occur in tectonic units, with the impact craters in thehighlands unit being far denser than those in the mare tectonicunit; larger impact craters exist in the highlands tectonic unit withrelatively complex tectonics; there are also some older residualimpact craters in the northwestern part of the highland tectonicunit in the north of Oceanus Procellarum‒Mare Frigoris area.

As indicated in Fig. 5, all the ridge structures of the linearstructures are located in the mare tectonic unit; and thoseextending in concentric rings in Mare Imbrium basin have mostlyformed in theMare Imbrium basin edge tectonic unit; mountains ofthe linear structures mostly occur in the mare tectonic unit andwere subject to large impact events; collapse structures also occurat the inner wall of large impact craters and mostly consist ofextended collapses under gravity; streams are found both in thehighlands tectonic unit and the mare tectonic unit, with a largerproportion of them lying in the transition zone between the twomajor tectonic units.

Fig. 7 shows the geologic profile of line AeA0 in Fig. 5 based ongeology of LQ-4 region. The tectonic framework in this region wastypically controlled by large impact events, especially in the MareImbrium basin, and basalt effusion events in the later periods,accompanied by minor impact events and tectonic deformation.

5. Regional tectonic evolution sequence of LQ-4

The tectonic evolution of lunar LQ-4 region is summarized basedon the discussion above and divided into the following stages:

AeA0 geologic profile.

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235234

(1) Early magma ocean stage on the Moon.

In its early years, the Moon was a partially melted or totallymelted magma ocean before it started to crystallize and differen-tiate in the form of cumulus crystals, as widely accepted, anddeveloped the proto-crust, mantle and residual magmas (KREEPcomponents) (Ouyang Ziyuan, 2005).

(2) Large impact stage.

Under the impact of large aerolites in the Prenectarian, the largeOceanus Procellarum impact basin formed. Subsequently at around3.85 Ga, Mare Imbrium basinwas formed under large impact events.KREEP rock features appeared in the highlands area around craters,suggesting that the impact events of Oceanus Procellarum and MareImbrium had dug out the residual KREEPmagma at depth. After that,the Sinus Iridum Impact and Plato Impact Craters, and ArchimedesImpact Crater in the southeast of Mare Imbrium took shape.

(3) Mare basalt infill stage.

After the large impact stage, this region was primarily subjectedto the infill activities of Mare Imbrium basalt. The mare basalt infillperiods in the regionmainly include late Imbrian and Eratoshenian.The late Imbrian mare basalt is mostly located to the east of MareImbrium, at the interface between the western edge of MareImbrium and Oceanus Procellarum, in Mare Frigoris and thenorthern part of Oceanus Procellarum. In Sinus Iridum area, thePlato Impact Crater was also overlaid by late Imbrian mare basalt,whereas the late Eratoshenian basalt mostly occurs in the west ofMare Imbrium and in Oceanus Procellarum.

The composition of the basalt shows regular changes with time.The TiO2 and FeO contents in the Eratoshenian mare basalt arenoticeably higher than that in the late Imbrian mare basalt,demonstrating different origins of the magma (Hiesinger et al.,2000, 2003, 2010; Xu et al., 2012).

(4) Tectonic deformation stage.

Ring structures are typically the result of impact actions, whichhave never stopped in any of the eras of the Moon. The linearstructures, on the other side, remain relatively complete sinceImbrian, though the older ones might have been obliterated ordamaged by impact events and basalt infills. The ridge structures, inparticular, mostly occurred in or after late Imbrian and some evenin Copernican, suggesting that this region was exposed to a rela-tively strong extrusion stress, probably coinciding with the thermalstate evolution across the Moon and isostasy in local areas. Thespatial distribution of the ridge structures, which reflects the ge-ometry of the basement to a certain degree, is the combinedproduct of basement and regional stresses (Bryan, 1973; Waskom,1975; Schultz, 2000; Wei et al., 2012).

Acknowledgment

Weexpress our gratitude to the key project (No. 2009AA122201)under the 863 program sponsored by Ministry of Science & Tech-nology that has funded our research, to CAS National AstronomicalObservatories that has offered us the Chang’e-1 data, and to NASAthat has offered us the Clementine, Lunar Prospector and LOLA data.

References

Basaltic Volcanism Study Project (BVSP), 1981. Basaltic Volcanism on the TerrestrialPlanets. Pergamon, New York.

Belton, M.J.S., Greeley, R., Greenberg, R., Geissler, P., McEwen, A., Klaasen, K.P.,Heffernan, C., Breneman, H., Johnson, T.V., Head III, J.W., Pieters, C., Neukum, G.,Chapman, C.R., Anger, C., Carr, M.H., Davies, M.E., Fanale, F.P., Gierasch, P.J.,Thompson, W.R., Veverka, J., Sagan, C., Ingersoll, A.P., Pilcher, C.B., 1994. Galileomultispectral imaging of the north polar and eastern limb regions of the Moon.Science 264, 1112e1115.

Bryan, W.B., 1973. Wrinkle-ridges as deformed surface crust on ponded mare lava.In: Proceeding of the 4th Lunar Science Conference, pp. 93e106.

Bugiolacchi, R., Guest, J.E., 2008. Compositional and temporal investigation ofexposed lunar basalts in the Mare Imbrium region. Icarus 197, 1e18.

Charette, M.P., McCord, T.B., Pieters, C., 1974. Application of remote spectralreflectance measurements to lunar geology classification and determination oftitanium content of lunar soils. Journal of Geophysical Research 79, 1605e1613.

Fagin, S.W., Worrall, D.M., Muehlberger, W.R., 1978. Lunar mare ridge orientations:implications for lunar tectonic models. In: Proceeding of the 9th Lunar andPlanetary Science Conference, pp. 3473e3479.

Giguere, T.A., Taylor, G.J., Hawke, B.R., 2000. The titanium contents of lunar marebasalts. Meteoritics & Planetary Science 35 (1), 193e200.

Glass, B.P., 1986. Solution of natural glasses in the geological environment. Journalof Advanced Ceramics 20, 723e732.

Golombek, M.P., Plescia, J.B., Franklin, B.J., 1991. Faulting and Folding in the For-mation of Planetary Wrinkle Ridges, Lunar and Planetary Science Conference.Lunar and Planetary Institute, Houston, pp. 679e693.

Hackwill, T., 2010. Stratigraphy, evolution, and volume of basalts in Mare Sereni-tatis. Meteoritics & Planetary Science 45 (2), 210e219.

Hiesinger, H., Jaumann, R., Neukum, G., Head, J.W., 2000. Ages of mare basaltson the lunar nearside. Journal of Geophysical Research 105 (E12),29239e29275.

Hiesinger, H., Head III, J.W., Wolf, U., Jaumann, R., Neukum, G., 2003. Ages andstratigraphy of mare basalts in Oceanus Procellarum, Mare Nubium, MareCognitum, and Mare Insularum. Journal of Geophysical Research 108 (E7), 5065.

Hiesinger, H., Head III, J.W., Wolf, U., Jaumann, R., Neukum, G., 2010. Ages andstratigraphy of lunar mare basalts in Mare Frigoris and other nearside mariabased on crater size-frequency distribution measurements. Journal ofGeophysical Research 115, 3003.

Hodges, C.A., 1973. Mare Ridges and Lava Lakes. Apollo 17 Prelim. Sci. Rep. NASAPublication SP-330, pp. 12e31.

Jolliff, B.L., Gillis, J.J., Haskin, L.A., 2000. Major lunar crustal terranes: surface ex-pressions and crust-mantle origins. Journal of Geophysical Research 105 (E2),4197e4216.

Kneissl, T., 2010. Map-projection-independent crater size-frequency determinationin GIS environmentsdNew software tool for ArcGIS. Planetary and Space Sci-ence 2010, 1016.

Kozlov, V.V., Sulidi-Kondratiev, E.D., 1969. Tectonic Map of the Moon. Ministry ofGeology of the USSR, Scientific Research Laboratory of the Geology of ForeignCountries, Moscow, 44 pp.

Kramer, G.Y., Jolliff, B.L., Neal, C.R., 2008. Distinguishing high-alumina mare basaltsusing Clementine UVVIS and Lunar Prospector GRS data: mare Moscovienseand Mare Nectaris. Journal of Geophysical Research 113.

Lawrence, D.J., Feldman, W.C., Barraclough, B.L., 1998. Global elemental maps of themoon: the Lunar ProsPector Gamma-Ray spectrometer. Science 281, 1984e1988.

Lawrence, D.J., Feldman, W.C., Barraclough, B.L., 2000. Thorium abundances on theLunar surface. Journal of Geophysical Research 105 (E8), 20307e20337. Wiec-zorek, M.A., Phillips, R.J., 2000. The ’Procellarum KREEP Terrane’: Implicationsfor mare volcanism and lunar evolution. Journal of Geophysical Research 105(E8), 20417-20430.

Lucchitta, B.K., 1976. Mare ridges and related highland scarpsdResult of verticaltectonism?. In: Proceedings of the 7th Lunar Science Conference, pp. 2761e2782.

Lucchitta, B.K., 1977. Topography, structure, and mare ridges in southern MareImbrium and northern Oceanus Procellarum. In: Proceedings of the 8th LunarScience Conference, pp. 2691e2703.

Lucey, P.G., Taylor, G.J., Malaret, E., 1995. Abundance and distribution of iron on theMoon. Science 268, 1150e1153.

Maxwell, T.A., El-Baz, F., Ward, S.H., 1975. Distribution, morphology, and origin ofridges and arches in Mare Serenitatis. Bulletin Geologic Society American 86,1273e1278.

Melosh, H.J., 1977. Global tectonics of a despun planet. Icarus 31, 221e243.Michael, G.G., Neukum, G., 2010. Planetary surface dating from crater sizeefre-

quency distribution measurements: partial resurfacing events and statisticalage uncertainty. Earth and Planetary Science Letters 294, 223e229.

Muehlberger, W.R., 1974. Structural history of southeastern Mare Serenitatis andadjacent highlands. In: Proceeding of the 5th Lunar Science Conference,101e110.

Neal, C.R., Taylor, L.A., 1992. Petrogenesis of mare basalts: a record of lunar volca-nism. Geochimica et Cosmochimica Acta 56, 2177e2211.

Neukum, G., Ivanov, B.A., Hartmann, W.K., 2001. Cratering records in the inner solarsystem in relation to the lunar reference system. Space Science Reviews 96, 55e86.

Ouyang, Z.Y., 1988. Cosmochemistry. Science Press, Beijing, pp. 93e145 (in Chinesewith English abstract).

Ouyang, Z.Y., 2005. Introduction to Lunar Sciences, China. Astronautic PublishingHouse, Beijing (in Chinese with English abstract).

Papike, J., Taylor, L., Simon, S., 1991. Lunar Minerals. In: Lunar Sourcebook.Cambridge University Press, New York.

Pieters, C.M., Staid, M.I., Fischer, E.M., 1994. A sharper view of impact craters fromClementine data. Science 266 (5192), 1844e1848.

J. Chen et al. / Geoscience Frontiers 5 (2014) 227e235 235

Potts, L.V., von Frese, R.R.B., 2003. Comprehensive mass modeling of the Moon fromspectrally correlated free-air and terrain gravity data. Journal of GeophysicalResearch 108 (E4), 5-1e;5e27.

Raitala, J., 1978. Tectonic pattern of mare ridges of the Letronne-Montes Riphaeusregion of the Moon. The Moon and the Planets 19, 457e477.

Schultz, R.A., 2000. Localization of bedding plane slip and backthrust faults aboveblind thrust faults: keys to wrinkle ridge structure. Journal of GeophysicalResearch 105 (E5), 12035e12052.

Scott, D.H., Diaz, J.M., Watkins, J.A., 1975. The geologic evaluation and regionalsynthesis of metric and panoramic photographs. In: Proceeding of the 6th LunarScience Conference, pp. 2531e2540.

Sharpton, V.L., Head II, J.W., 1988. Lunar mare ridges: analysis of ridge-crater in-tersections and implications for the tectonic origin of mare ridges. In: The 18thLunar and Planetary Science Conference. Lunar and Planetary Institute, Hous-ton, pp. 307e317.

Strom, R.G., 1964. Analysis of Lunar Lineaments. I. Tectonic Maps of the Moon.University of Arizona: the Lunar and Planetary Laboratory, pp. 205e216.

Strom, R.G., 1972. Lunar mare ridges, rings and volcanic ring complexes, The Moon.In: Proceedings from IAU Symposium.

Taylor, S.R., 1975. Lunar Science: a Post-Apollo View. Pergamon, New York, 372 pp.Taylor, G.J., Warren, P., Ryder, G., Delano, J., Pieters, C., Lofgren, G., 1991. Lunar rocks.

In: Heiken, G.H., Vaniman, D.T., French, B.M. (Eds.), Lunar Sourcebook.Cambridge University Press, Cambridge, UK, pp. 183e284.

Thomas, R.W., 2010. Evidence of recent thrust faulting on the moon Revealed by theLunar Reconnaissance Orbiter camera. Science 329, 936.

Waskom, J.D., 1975. Wrinkle ridges and mare basin structure. In: 6th Lunar ScienceConference, Abstract: 1286.

Watters, T.R., Robinson, M.S., Beyer, R.A., Banks, M.E., Bell III, J.F., Pritchard, M.E.,Hiesinger, H., van der Bogert, C.H., Thomas, P.C., Turtle, E.P., Williams, N.R., 2010.Evidence of recent thrust faulting on the Moon Revealed by the Lunar Recon-naissance Orbiter camera. Science 329 (5994), 936e940.

Wei, W., Liu, S.F., Wang, K., 2012. Formation mechanism of lunar ridges and thecorrelation analysis with tidal forces. Modern Geology 26 (1), 198e204 (inChinese with English abstract).

Wilhelms, D.E., 1987. The Geologic History of the Moon. U. S. Government PrintingOffice, Geological Survey Professional Paper, Washington DC.

Wilhelms, D.E., McCauley, J.F., 1971. Geologic Map of the Near Side of the Moon.USGS IMAP: 703.

Xu, Y.B., Yan, D.P., Yu, T.S., Wang, X., 2012. The filling process of mare basalts fromlate Imbrian to Eratoshenian in Mare Imbrium,. Acta Geologica Sinica 86 (8),1306e1319 (in Chinese with English abstract).

Yingst, R.A., Gregg, T.K.P., 2009. Lunar geologic mapping: a preliminary map of aportion of the Marius Quadrangle. In: 40th Lunar and Planetary Science Con-ference (Lunar and Planetary Science XL), held March 23e27, 2009 in TheWoodlands, Texas.

Yue, Z.Y., Ouyang, Z.Y., Li, H.B., Ji.Z., Liu, Wu, G.G., 2007. The origin and geologicalsignificance of lunar ridges. Chinese Journal of Geochemistry 26 (4), 418e424.

Zuber, M.T., Smith, D.E., Lemoine, F.G., 1994. The shape and structure of the Moonfrom the Clementine mission. Science 266, 1839e1843.