Secular changes of water chemistry in shallow-water Ediacaran ocean: Evidence from carbonates at Xiaofenghe, Three Gorges area, Yangtze Platform, South China

Hohl, Simon V.; Becker, Harry; Gamper, Antonia; Jiang, Shao‐Yong; Wiechert, Uwe; Yang, Jin; Wei, Hai-Zhen

doi:10.1016/j.precamres.2015.09.006

Cited by 29 publications

(14 citation statements)

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“…Late fluid-flow overprint is typical for many Neoproterozoic carbonates and may also have altered the Cd isotope signatures. However, Hohl et al (2015) have shown that, with the exception of the cap dolostones, carbonates at Xiaofenghe were not much affected by fluids (SEM pre-screening, no co-variation of d 18 O with 87 Sr/ 86 Sr or Mn/Sr); thus, their trace element budgets and isotopic compositions most likely reflect partitioning and incorporation from Ediacaran seawater. In the cap dolostones ε 112/110 Cd > 0, while low Cd and N concentrations (Fig.…”

Section: Resultsmentioning

confidence: 93%

“…2d). If the Cd isotopic variations observed are controlled by changes in seawater salinity at the Xiaofenghe depositional site, estuarine mixing of seawater and river water, as described in Hohl et al (2015), may account for the observed variation. The correlation between Y/Ho and ε 112/110 Cd (see Fig.…”

Section: Resultsmentioning

confidence: 96%

“…The effect of authigenic sulphides on Cd isotope fractionation is still not well understood. Cadmium isotope data on hydrothermal sulphide ores (Schmitt et al, 2009;Wen et al, 2016) and quantum chemical calculations (Yang et al, 2015) suggest that the light isotopes of Cd would be preferentially bound into the sulphide phase. On the other hand, Rolison et al (2015) did not find the high ε 112/110 Cd in the deeper parts of the Black Sea water column that one would expect.…”

Section: Resultsmentioning

confidence: 99%

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Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Hohl¹,

Galer²,

Gamper³

et al. 2016

Geochem. Persp. Let.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

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Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Hohl¹,

Galer²,

Gamper³

et al. 2016

Geochem. Persp. Let.

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“…The Ediacaran (known as the Sinian in China) is widely distributed in south China and includes the Doushantuo Formation (635~551 Ma) and the Dengying Formation (551~541 Ma; Bowring et al, ; Y. L. Chen, Chu, Zhang, & Zhai, ; Condon et al, ; S. Zhang et al, ). The Ediacaran in China has been of scientific interest for more than a century with numerous paleontological (McFadden, Xiao, Zhou, & Kowalewski, ; Xiao et al, ; Yin et al, ; Yuan, Chen, Xiao, Zhou, & Hua, ), paleogeographical, paleoclimatological, and paleoecological investigations being undertaken (Hohl et al, ; Jiang, Shi, Zhang, Wang, & Xiao, ; D. Li et al, ; D. Li, Ling, et al, ; Ling et al, ; Tahata et al, ; Wang, Shi, Jiang, & Tang, ). The dolomite of the Dengying Formation has long been studied by petroleum geologists for it is one of the most important gas‐producing reservoirs in the Sichuan Basin (Figures and ).…”

Section: Introductionmentioning

confidence: 99%

“…L. Chen, Chu, Zhang, & Zhai, 2015;Condon et al, 2005;. The Ediacaran in China has been of scientific interest for more than a century with numerous paleontological (McFadden, Xiao, Zhou, & Kowalewski, 2009;Xiao et al, 2014;Yin et al, 2013;Yuan, Chen, Xiao, Zhou, & Hua, 2011), paleogeographical, paleoclimatological, and paleoecological investigations being undertaken (Hohl et al, 2015;Jiang, Shi, Zhang, Wang, & Xiao, 2011;D. Li et al, 2009;Ling et al, 2013;Tahata et al, 2013;Wang, Shi, Jiang, & Tang, 2014).…”

Section: Introductionmentioning

confidence: 99%

Sequence stratigraphy and facies architecture of a mound‐shoal‐dominated dolomite reservoir in the late Ediacaran Dengying Formation, central Sichuan Basin, SW China

Wei

Yang

et al. 2018

Geological Journal

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The late Ediacaran Dengying Formation is one of the oldest carbonate microbial mound and shoal reservoirs in the world. This formation has recently attained widespread attention with the significant discovery of a huge volume of natural gas in the central part of the Sichuan Basin, South China. To fully understand the depositional processes and impacts on the reservoir, a comprehensive study of the sequence stratigraphy and facies architecture as well as reservoir analysis was undertaken by integrating analysis of seismic, well-logging, and core data. The D4 member consists of nine types of lithofacies representing distinguished depositional environments.These types of lithofacies can be grouped into five types of lithofacies associations, which are platform-margin shoal, mound-shoal complex, microbial mound, lagoon, and tidal flat. The platform margin was dominated by shoal and mound-shoal complexes, whereas the platform interior contained microbial mounds, lagoon, and tidal flat facies. We constructed a high-frequency sequence stratigraphy framework and identified two third-order sequences (SQ1 and SQ2) in the Dengying Formation and five fourth-order sequences (SQ2-1 to SQ2-5) in the fourth member of the Dengying Formation (the D4 member). In the D4 member, the thickness of the mound-shoal complex increases from the bottom to the top. The reservoir spaces in this Formation generally have low porosity and low permeability and include dissolution vugs and caves, and intercrystalline vugs and pores. Three types of reservoirs are identified, which are early-stage karst mound-shoal reservoirs, late-stage karst superimposed reservoirs, and other factors impacted reservoirs. Microbial mound and shoal facies are the material basis for a favourable reservoir, with the key factor for the improvement of reservoir quality being early-stage meteoric-water dissolution related to fourth-order sequence boundaries. The tectonic unconformity that was formed at the end of the Sinian Stage dominates the development and distribution of the most beneficial reservoir beds. Organic acid, hydrothermal fluid, and tectonic fracturing processes modified the reservoir beds in advance. Results from our investigation enable us to propose a model for the depositional evolution and reservoir formation in the D4 member of the Dengying Formation.

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Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia

Vitek

Suosaari

Oehlert

et al. 2023

The Depositional Record

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Hamelin Pool, Shark Bay, Western Australia hosts the world's largest and most extensive assemblages of living marine microbialites, comparable in size and shape to ancient structures found throughout the fossil record. Here, we document the internal fabrics of modern microbialites collected throughout Hamelin Pool. Meso‐ and microscale observations of microbialite polished slabs and thin section scans, optical microscopy, and scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy formed the basis for a fabric classification system that combines accretionary mat type with microfabric. Accretionary mat types included pustular, smooth, colloform, as well as ‘transitional’ mats that are a cross between pustular and smooth mats. Mapping of fabrics in 45 microbialite heads indicated bi‐directional evolution. An upward progression of fabrics corresponded to changes in mat type as the head grew upward into shallower water. A downward evolution of microfabrics occurred as surface mats transitioned into the subsurface of the microbialite structure. Downward microfabric evolution occurred as a result of early taphonomic processes, and involved a progression from the original depositional architecture to subsequent stages of micritic thickening, and finally, cement infilling. The observed bi‐directional evolution of microbialite microfabrics within Hamelin Pool offers a conceptual framework for the study of modern microbialites, not simply as the sole product of accretionary mat types but rather as the combined result of the activity of surface mats and their taphonomic evolution. Early taphonomic processes induce further lithification of the microbialites which may enhance preservation potential in the geological record.

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Secular changes of water chemistry in shallow-water Ediacaran ocean: Evidence from carbonates at Xiaofenghe, Three Gorges area, Yangtze Platform, South China

Cited by 29 publications

References 89 publications

Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Cadmium isotope variations in Neoproterozoic carbonates - A tracer of biologic production?

Sequence stratigraphy and facies architecture of a mound‐shoal‐dominated dolomite reservoir in the late Ediacaran Dengying Formation, central Sichuan Basin, SW China

Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia

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