The Middle Cretaceous Carbonate Ramp_Konidari

The Middle Cretaceous Carbonate Ramp

of the Northern Sinai (Egypt)

Sequence Stratigraphy and Facies Distribution

KONIDARI ELISSAVET 100352445

Contents

Setting of North Sinai (Regional, Tectonic and Geological)

Mid-Cretaceous Carbonate ramp

Mid-Cretaceous rock units

Facies of carbonate ramp

Exploration of H/C

Elements

Setting of North Sinai

o Active seismic area (Middle Miocene rift, Northeastern Africa – Arabian Peninsula)

o Tectonic processes because of Tethys

o The Carbonate platform covered Sinai’s peninsula (Cenomanian sea level rise)

o Excellent wide lateral extended outcrops

o North - Mediterranean Sea

o South – South Sinai

o West – Port Said and Channel Suez

o East – Gaza and Israel

o Area 27,500 sq.km

oGradual Lateral Deepening to the North(Upper Aptian to Albian)oNorth dipping ramp geometry with a shelf break (inner ramp)oOrganic barriers, shoals (high energy), shoreface deposits and subtidal (low energy)oContinuous transgressive systems resulted in a shallow shelf geometryoMid-Albian – Cenomanian sea level rise(shallow marine)

o southward extension of the rampo shift of the shoreline o flooding of a delta system

Mid – Cretaceous carbonate ramp

Fig. 1. Early Aptian palaeoenvironments redrawn from Masse et al. (1993) where carbonate platform depositional environment took place

Paleogeographical maps to illustrate the Late Aptian and Late Cenomanian environments of deposition.

The carbonate ramp of the northern Sinai passed laterally into a carbonate platform with a steeply inclined slope further northeast (Sass & Bein 1982).

Explanation: 1, exposed swell2, terrestrial realms marked by fluvial sandstones3, deltaic sediments4, inner platform-ramp with siliciclastic deposits5, inner platform-ramp with mixed carbonate-siliciclastic deposits6, inner platform-ramp with carbonate deposits7, inner ramp with carbonate shoals (northern Sinai) 8, platform margin with reefs (northern Israel)9, platform slope-mid- and outer ramp10, basin11, position of the sections.

o Lower delta dominated rampo Unit A - Malha Formationo Upper Aptian-Lower Albiano Marine carbonates with siliciclastics , sandstones and limestones

oUpper carbonate rampo Unit B - Galala Formationo Middle Albian-Cenomanian o Overlies the Malha formation o Low and high energy conditionso Different facies (lagoonal , tidal and open-marine)o Lower part consists of sand bodies with calcareous mudstones, shales and

limestones with plant remains and oysterso Middle and upper parts comprise fossiliferous limestone, marls and mudstoneso Fossils: benthic foraminifera, ostracodes, palynomorphs(strongly oxidizing

bottom water in shallow marine environment or a later weathering), rudist biostromes, gymnosperms, ferruginous ooids

Mid-Cretaceous Units

o Middle Albian – low sediment accumulation rate

o Early Cenomanian 4 times higher sedimentation

o Upper Albian: strong dolomitization – Defined boundary by foraminifera – 24 microfacies

o Cenomanian : eustasy and redusing of the extentional tectonic influenced North Sinai

o Cenomanian: delta progradation, karstification, retrogradation of the shoreline and ferruginous ooids are related to the humid climate of this period

Mid-Cretaceous Units

Facies of Carbonate RampCharacterized by 5 different facies from proximal to distal ramp

1.Tidal Environment: alteration of dolomites with mudstones, wackestones with bioclasts and ooids and marls2.Inner Ramp: wackestones with small benthic foraminifera, gastropods, packstones and marls with oysters and gastropods3.Shallow Ramp: Alteration of wackestones and packstones(influence of wave activity), fine grained bioclasts with bivalves, coarser packestones with enriched in echinoids which indicate moderate – low energy depositional environment, rudist biostrome and oolithic grainstones4.Shoals: Massive beds with lateral thinning and thickening, cross-bedding with low angle, oolithic grainstones with 90% of ooids, echionoids, bivalves, gastropods and bryozoans , high energy barrier shoal5.Mid-Ramp: Marls with limestones, laterally change into wackestones and mudstones with foraminifera and echinoids

Exploration of H/C

o1910 Beginning of explorationo4 major sequences in North Sinai

oPaleozoic , marine environmento Triassic to Early Cretaceous ,marine(deep and shallow)

and continental environmento (source, reservoir and seal)

oUpper Cretaceous-Late Eocene (Carbonates-potential reservoir)

oOligocene-Late Miocene, absence of rock because of the Gulf of Suez rifting, two formation during Miocene

oHigh tectonic acitivity – produce of carbonate reservoirs, evaporite seals and favorable traps

ElementsoSource rock

o Jurassic shaleoKerogen Type II-III (oil and gas)o TOC 2%

oReservoir rocko Late Cretaceous carbonateoMatulla formation(Unit B)o13% porosityo81md permeabilityo30billion cf of gas

o Trap rocko Paleocene shale(Esna)o Vertical sealo Normal faults –effective sealing mechanism

o Trapso Structural(anticlines)o Stratigraphic(reservoir embedded in fine

grained shaly - silty rock, anhydrite)o Combination

It is fair to say that the north Sinai remains high in H/C exploration with many untested plays because do not forget that…….wars smell like OIL….

Thank you…

References

• Alsharhan A.S. et al. (1996), “Geologic setting and hydrocarbon potential of north Sinai, Egypt”, BULLETIN OF CANADIAN PETROLEUM GEOLOGY VOL 44, NO.4, P 615-631

• Bachmann M. et al.(2003), “Timing of Mid-Cretaceous carbonate platform depositional cycles, northern Sinai, Egypt”, Elsevier 3135(2003)1-32

• Bachmann M. et al. (1999), “The Middle Cretaceous carbonate ramp of the northern Sinai:Sequence stratigraphy and facies distribution”, Geological Society, London, Special Publications 1998, v.149, p. 253-280

• El Beialy et al. (2010), “Palynology of the Mid-Cretaceous Malha and Galala Formations, Gebel el Minshera, North Sinai, Egypt”, Palaios 2010 v.25, p.517-526