Platform carbonates of the Upper Jurassic Mozduran formation in the Kopet Dagh Basin, NE Iran—facies, palaeoenvironments and sequences

Lasemi, Yaghoob

doi:10.1016/0037-0738(95)00041-6

Cited by 63 publications

(35 citation statements)

References 11 publications

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“…presence of aragonite relicts, shattered micritic envelope, acicular to fibrous isopachous marine cement, presence of diffuse laminae and a number of spalled external ooid laminae, early diagenetic dolomites and evaporites) and geochemical evidence (such as elevated Sr) also suggested that during the Upper Jurassic, aragonite was the predominant original carbonate mineralogy in the Mozduran limestone (Iran) from the shallowest part of the basin (Adabi and Rao 1991), while the majority ofdata (e.g. absent of aragonite relict or pseudomorph, abundant marine calcite cements and calcitic biota, absence of evaporite and very low Sr values) from the relatively deeper part of the basin (below wave base) are more characteristic of calcite than aragonite (Adabi and Rao 1996;Lasemi 1996;Adabi 1997).…”

Section: Upper Jurassic Carbonatesmentioning

confidence: 99%

A re-evaluation of aragonite versus calcite seas

Adabi

2004

Carbonates Evaporites

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Some workers have argued that the mineralogy of ancient carbonates may have been different from that of modem sediments, with calcite being considered the dominant mineral during the Ordovician, Devonian-mid Carboniferous, and JurassicCretaceous to Early/Middle Cenozoic (e.g. Sandberg 1983;Wilkinson and Algeo 1989). Variation in carbonate mineralogy has been related to the position of global sea level (emergent or submergent modes, Wilkinson et al. 1985), change in rates of seafloor spreading (e.g. Mackenzie and Pigott 1981;Hardie 1996), PC0 2 level (e.g. Sandberg 1985Mackenzie and Morse 1992; Hallock 1997) and Mg/Ca ratios related to spreading rate (e.g. Stanley and Hardie 1998). However, other researchers suggest that the assumption of change of original carbonate mineralogy through time needs to be re-evaluated in the light of mineralogical change that is related to water temperature or latitudes (e.g. Nelson 1988). Evaluation of Ordovician (Arenig to Ashgill) Gordon Group carbonates of Tasmania (Australia), based on petrographic (e.g. abundant Chlorozoan biota, and oomold texture) and geochemical criteria (such as high Sr/Na ratios) indicated that aragonite (not calcite) was the predominant mineral in these warm water, subtropical carbonates (Rao 1990). Petrographic (e.g. presence or absence of aragonite relicts, abundant acicular to fibrous isopachous marine cement, presence of diffuse laminae and a number of spalled ooids) and geochemical evidences (such as elevated Sr) in the Upper Jurassic Mozduran limestone, in Kopet-Dagh Basin in northeast Iran, showed variation in carbonate mineralogy, in spite of similar atmospheric PC0 2 level, global sea-level and tectonic setting. This is evidenced by aragonite occurring in the shallowest part of the basin (Adabi and Rao 1991) and mainly calcite with some aragonite forming in the relatively deeper water (below wave base) (Adabi 1997). Carbonate mineralogy in Recent shallow marine carbonates, and in experimental studies, varies with seawater temperature. In the Recent, aragonite is the predominant mineral in warm, shallow marine carbonates and calcite the dominant mineral in marine cool water carbonates (James and Clarke 1997). Therefore,variations in carbonatemineralogy in the Mozduranlimestone are attributedto seawater temperature assuming invariant seawater chemistry prevailed in the Upper Jurassic. Several Jurassic examples show variations in ooid carbonate mineralogy, such as the Upper Jurassic Smackover oolite of the Gulf Coast region (southern Arkansas and northern Louisiana) and Upper Jurassic ooids in the Purbeck limestones of Swiss and French Jura. These results are not in agreement with the concept of a "calcite sea" during the Ordovician and the Upper Jurassic periods. Very recently, Westphal and Munnecke (2003) showed that in spite of the tendency of abiotic precipitates (Sandberg 1983) and skeletal mineralogy (Stanley and Hardie 1999) to follow the general trend of calcite seas and aragonite seas, organisms with calcite and aragonite mineralogy coexis...

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Section: Upper Jurassic Carbonatesmentioning

confidence: 99%

A re-evaluation of aragonite versus calcite seas

Adabi

2004

Carbonates Evaporites

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“…In this microfacies, moreover, intraclasts result from erosion and rip-up as well as erosion of older deposits by stormy currents [35].…”

Section: Discussionmentioning

confidence: 99%

Facies Analysis and Depositional Environment of Upper Permian Rocks in Darin Section, East-Central Iran

Emraninasab¹,

Adabi²,

Majidifard³

et al. 2017

OJG

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Deposits of Permian rocks in Kalmard Block are recognized with Khan Group, showing various characteristics in different outcrops. This group is made up of three informal formations, namely Chili, Sartakht and Hermez. Upper Permian deposits (Hermez Formation) are composed chiefly of lateritic and carbonate rocks. This formation is composed of 65.5 m lateritic soils, lateritic sandstone, limestone, dolomite and dolomitic limestone in the Darin section. This formation unconformably overlies middle Permian siliciclastic and evaporite deposits (Sartakht Formation), where as it is depicted underlying an erosional unconformity above lateritic deposits of lower Triassic (Sorkh Shale Formation). According to lithologic and microscopic investigations, the deposits of Hermez Formation can be divided into 1 siliciclastic petrofacies and 14 carbonate microfacies. Field observations, along with microscopic examinations, have resulted in identifying tidal flat, lagoon, shoal and open marine environments in the rocks of the studied formation. Vertical changes of microfacies and depth variation curve point to the high thickness of the microfacies of lagoon, tidal flat and shoal environments and low thickness of open marine microfacies. Hermez Formation rocks in Darin section are deposited in a low-angle homoclinal ramp, mostly in the inner ramp, located in the southern Paleo-Tethys Ocean.

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“…Large size of these particles and their relative sorting are among factors determining high energy in this facies. In addition, small amount of Isopachous cement implies high deposit accumulation rate [32]. Lack of gravity cement is a sign of not moving out of water [11] [33].…”

Section: Discussionmentioning

confidence: 99%