Sr-isotope Stratigraphy as a Tool to Refine the Sequence Stratigraphy of the Barremian - Aptian (Early Cretaceous) Carbonate Platform in the UAE

Author(s):  
Rutai Duan ◽  
Thomas Steuber ◽  
Klaus Mueller ◽  
Zinhom El Wazir
2017 ◽  
Vol 47 (3) ◽  
pp. 521-543 ◽  
Author(s):  
Cristian Guacaneme ◽  
Marly Babinski ◽  
Gustavo Macedo de Paula-Santos ◽  
Antonio Carlos Pedrosa-Soares

ABSTRACT: High-resolution chemostratigraphic data of carbonates from the Sete Lagoas Formation (Bambuí Group) show large variations on the C, O, and Sr isotope compositions. Impure limestones at the base show primal δ13C values between -1.0 and 0‰, and δ18O values between -12.0 and -8.0‰. However, some dolostones demonstrate δ13C values varying from +2.8 to -6.8‰, highly radiogenic 87Sr/86Sr ratios (>0.7111), and low Sr concentrations (<350 ppm) related to post-depositional processes. In contrast, pure limestones at the top show very positive δ13C values between +8.3 and +12.8‰, δ18O values between -10.0 to -6.0‰, and 87Sr/86Sr ratios from 0.7073 to 0.7086, with high Sr concentrations (>900 ppm). They are linked to depositional controls on the carbonate platform, such as fluvial and/or submarine water influx, in which carbonates deposited on the proximal sector exhibit significant Sr isotopic variations and those on the distal sector were not subject to such controls, resulting in very homogeneous Sr isotope profiles. However, 87Sr/86Sr ratios of the distal carbonates are less radiogenic than carbonates expected for late Ediacaran (~0.7085). This discrepancy suggests a restricted marine basin without Sr isotopic homogenization with contemporary oceans and, in this case, global correlations based on Sr isotope stratigraphy are not reliable.


2019 ◽  
Vol 99 ◽  
pp. 71-95 ◽  
Author(s):  
Cristian Victor Mircescu ◽  
Ioan I. Bucur ◽  
Emanoil Săsăran ◽  
George Pleş ◽  
Răzvan Ungureanu ◽  
...  

2021 ◽  
Author(s):  
Mohammadsadegh Dehghanian

Abstract Asmari Formation is the thick sequence of carbonate sediment in the range of Oligocene-Miocene which is deposited in the foreland basins of the Zagros and is considered as the original and most famous reservoir rock of Zagros basin. To study of lithostratigraphic units and sequence stratigraphy of this Formation, the section in the southeast of Norabad was selected. Field study indicated that Asmari Formation possessed the thickness of 401.5m and included 9 lithostratigraphic units. According to the study of microfacies, Stacking pattern and identification of main sequence level, three depositional sequences including two-second order and one-third order sequence were recognized. The sea-level curve in the studied section indicated that it was correspondence to the global sea level curve. These facies deposited in five environmental sedimentations as follow Open Sea Shelf (Fore Barrier), Bar, Lagoon, Back bar shelf, and Shoal. The environment is part of a carbonate platform that has been formed on an open shelf. In addition, according to the Study of foraminifer dispersion pattern the range of Asmari Formation in Norabad was suggested to be Oligocene (Rupelian- Chattian) to lower Miocene (Aquitanian- Burdigalian).


2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Rudolph Scherreiks ◽  
Marcelle Boudagher-Fadel

The Pelagonian stratigraphy of the Internal Hellenides consists of a Permo-Triassic basement and an Upper Triassic and Jurassic carbonate platform formation that has been overthrust by the Eohellenic ophiolite sheet during the Early Cretaceous. Intensive erosion, during the Cretaceous, removed most of the ophiolite and parts of the Jurassic formation. It is hypothesised that uplift and erosion of eastern Pelagonia was triggered by the break-off of the subducted oceanic leading edge of the Pelagonian plate. An investigation of the rocks that succeed the erosional unconformity shows that they constitute a shear-zone that is tectonically overlain by Cretaceous platform carbonates. Geochemical analyses of the shear-zone rocks substantiate that they are of mid-oceanic ridge and island arc provenience. Eastern Pelagonia collided with a Cretaceous carbonate platform, probably the Paikon forearc basin, as the Almopias ocean crust subducted beneath that island–arc complex. The Cretaceous platform, together with a substrate of sheared-off ocean floor mélange, overthrust eastern Pelagonia as subduction continued, and the substrate was dynamically metamorphosed into cataclastic rocks, mylonite, phyllonite and interpreted pseudotachylite. This complex of Cretaceous platform rocks and a brittle-ductile shear-zone-substrate constitute the here named Paikon–Palouki nappe, which was emplaced during Early Palaeocene. The Paikon–Palouki nappe did not reach Evvoia. Seismic tomographic models of the Aegean region apparently depict images of two broken-off ocean-plate-slabs, interpreted as Almopias-lithosphere-slabs. It is concluded that the western Almopias slab began to sink during the Early Cretaceous, while the eastern Almopias slab broke off and sank after the Paikon–Palouki nappe was emplaced in the Early Palaeocene.


2009 ◽  
Vol 180 (2) ◽  
pp. 105-115 ◽  
Author(s):  
Jean-Pierre Masse ◽  
Michel Villeneuve ◽  
Emmanuelle Leonforte ◽  
Jean Nizou

Abstract In the western part of the Castellane tectonic arc, the so-called “ Provence platform area “, corresponding to the foreland of the Alpine nappes (figs. 1–2), is marked by Tithonian-Berriasian shallow water carbonates capped by hemipelagic sediments deposited from the Valanginian up to the Aptian-Albian. A detailed biostratigraphic study of the Berriasian succession, based on calcareous algae and foraminifera, allows us to distinguish a Lower to Middle Berriasian, with Clypeina sulcata, Clypeina isabellae and Holosporella sarda, from an Upper Berriasian with Pfenderina neocomiensis, Danubiella cernavodensis, Falsolikanella campanensis and Macroporella praturloni (fig. 3). We performed a field survey of 30 sites located from Quinson to the west, and Escragnolles to the east (figs. 4–5) including the study of measured stratigraphic sections and the collection of samples for biostratigraphic interpretations. These stratigraphic investigations show that below the Valanginian beds, the Berriasian platfom carbonate succession, is locally incomplete, i.e. Upper Berriasian beds are frequently absent. During the Early and Middle Berriasian, depositional environments are marked by a strong bathymetric instability, with frequent subaerial exposure events, and a significant marine restriction; by contrast, during the Late Berriasian, the overall biological diversity increases and water agitation as well, which means a significant marine opening towards the basin. The Upper Berriasian hiatus is consequently regarded as the result of a Berriasian/Valanginian and/or a lowermost Valanginian erosion (fig. 6). The spatial distribution of complete or truncated Berriasian successions identifies east-west bands, in each band truncated series are located northward and complete series are located southward. Bands are limited by thrust or strip faults interpreted as palaeofaults reactivated during the Alpine orogeny (fig. 7). These fault-bounded blocks, 3 to 10 km in width, known as the Aiguine, La Palud-sur-Verdon, Carajuan-Audibergue and Peyroulles-La Foux blocks, are southerly rotated by 1 to 2o. We regard this structural architecture as the result of basinward tilting of blocks. Due to their rotation, the uplifted parts were eroded whereas the depressed parts were protected against erosion (fig. 8). Such a dynamic behavior reflects a distensive tectonic regime, which has been active at least during the Valanginian, that is after the drowning of the North-Provence carbonate platform. These structural events are considered as the regional expression of the Neocimmerian tectonic phase coupled with an enhancement of the Atlantic rifting. The orientation of the major Alpine structural elements (folds and faults) of the Castellane arc, is mostly inherited from these early Cretaceous tectonic events.


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