Dolomitization and hydrotectonic model of burial dolomitization of the Furongian-Lower Ordovician carbonates in the Tazhong Uplift, central Tarim Basin, NW China: Implications from petrography and geochemistry

Hu, Mingzeng; Ngia, Ngong Roger; Gao, Da

doi:10.1016/j.marpetgeo.2019.04.018

Cited by 21 publications

(5 citation statements)

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“…The studied limestones display high Y/Ho ratios with an average of 46.26 (29.33-70.00), which is consistent with detritus-free marine sediments (average 45.50) [69]. Further, the lack of correlation between Y/Ho ratios, Ce/Ce*, and Al and Zr contents in the studied limestone implies little or negligible terrestrial contamination [74].…”

Section: Siliciclastic Impuritiessupporting

confidence: 73%

“…Finally, a negative correlation between Ce/Ce* and La/Sm N ratios have been used as evidence of diagenetic influence on Ce [97][98][99], and this correlation is not apparent in our carbonates (Figure 8c). Similarly, an absence of correlation between Ce/Ce* and Eu/Eu* implies a negligible or absence of influence of post-depositional alteration on the measured Ce/Ce* [3,7,74,84,87,100]. Our samples display a weak correlation (Figure 8d-f), which implies negligible or no diagenetic impact on Ce anomalies.…”

Section: Diagenetic Influencementioning

confidence: 65%

“…between Y/Ho ratios, Ce/Ce*, and Al and Zr contents in the studied limestone implies little or negligible terrestrial contamination [74].…”

Section: Siliciclastic Impuritiesmentioning

confidence: 82%

“…It has been shown that the studied limestones mostly display a seawater signature including (1) negative Ce anomalies, (2) superchondritic Y/Ho (47 ± 4), and depleted LREE relative to HREEs ((Nd/Yb) N = 0.46-1.12; ave. 0.72 and (Pr/Yb) N = 0.50-1.40; 0.73) ( Figures 6a-c and 10). The Ce* anomaly in carbonates is considered as a superior proxy for revealing the redox-state of the ancient seawater [3,8,74]. The studied samples exhibit negative Ce* anomalies, typical of modern oxygenated seawater [9,77,78,80,84,91,118].…”

Section: Early Cretaceous Paleoenvironmental Implicationsmentioning

confidence: 98%

“…This is important because contamination by terrestrial clays can control the primary REEs + Y contents of ancient marine carbonates [4,6,71,72]. A small quantity of terrestrial particulate matter (i.e., shale), which has high REE contents with distinctly non-seawater-like patterns [73], may dramatically modify original REE patterns and cause a decrease in both the extent of LREE depletion and Y/Ho ratios [3,4,74]. Several lines of evidence suggest that the studied limestone displays a diagnostic seawater signature: (1) negative Ce anomalies (0.38-0.81; average 0.57), (2) depleted LREE and (3) superchondritic Y/Ho (average 46.26) ( Figure 6a) (e.g., [4]).…”

Section: Siliciclastic Impuritiesmentioning

confidence: 99%

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REE Characteristics of Lower Cretaceous Limestone Succession in Gümüşhane, NE Turkey: Implications for Ocean Paleoredox Conditions and Diagenetic Alteration

et al. 2020

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Trace and rare earth elements (REEs) are considered to be reliable indicators of chemical processes for the evolution of carbonate systems. One of the best examples of ancient carbonate successions (Berdiga Formation) is widely exposed in NE Turkey. The Lower Cretaceous limestone succession of Berdiga Formation may provide a case study that reveals the effect of ocean paleoredox conditions on diagenetic alteration. Measurement of major, trace and REEs was carried out on the Lower Cretaceous limestones of the Berdiga Formation, to reveal proxies for paleoredox conditions and early diagenetic controls on their geochemistry. Studied micritic limestone microfacies (MF-1 to MF-3) indicate deposition in the inner platform to a deep shelf or continental slope paleoenvironment during the Hauterivian-Albian. The studied limestone samples mainly exhibit low Mg-calcite characteristics with the general chemical formula of Ca98.35–99.34Mg0.66–1.65(CO3). They are mostly represented by a diagnostic REE seawater signature including (1) slight LREE depletion relative to the HREEs (ave. 0.72 of Nd/YbN and ave. 0.73 of Pr/YbN), (2) negative Ce anomalies (Ce/Ce* = 0.38–0.81; ave. 0.57), (3) positive La anomaly (La/La* = 0.21–3.02; ave. 1.75) and (4) superchondritic Y/Ho (ave. 46.26). Studied micritic limestones have predominantly low Hf (bdl to 0.5 µg/g), Sc (bdl to 2 µg/g) Th (bdl to 0.9 µg/g) contents suggesting negligible to minor shale contamination. These findings imply that micritic limestones faithfully record chemical signals of their parental and diagenetic fluids. The succession also exhibits high ratios of Eu/Eu* (1.01–1.65; ave. 1.29 corresponding to the positive Eu anomalies), Sm/Yb (1.26–2.74; ave. 1.68) and La/Yb ratios (0.68–1.35; ave. 0.9) compared to modern seawater and wide range of Y/Ho ratios (29.33–70.00; ave. 46.26) which are between seawater and hydrogenetic Fe-Mn crusts. Several lines of geochemical evidence suggest water-rock interaction between parental seawater and basaltic rocks at elevated temperatures triggered by hydrothermal activity associated with Early Cretaceous basaltic magma generation. The range of Ce/Ce* values is suggestive of mostly oxic to dysoxic paleoceanographic conditions, with a sudden change to dysoxic conditions (Ce/Ce* = 0.71–0.81), in the uppermost part of the MF-1. This is followed by an abrupt deepening paleoenvironment with a relative increase in the oxic state of the seawater and deposition of deeper water sediments (MF-2 and MF-3) above a sharp transition. The differences in microfacies characteristics and foraminifera assemblage between MF-1 and overlying facies (MF-2 and MF-3) may also confirm the change in paleoceanographic conditions. Therefore, REEs data obtained from studied limestones have the potential to contribute important information as to regional paleoceanographic conditions of Tethys during an important period in Earth history.

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Section: Siliciclastic Impuritiessupporting

confidence: 73%