Carbon, oxygen and strontium isotopic and elemental characteristics of the Cambrian Longwangmiao Formation in South China: Paleoenvironmental significance and implications for carbon isotope excursions

Zhang, Pengyuan; Wang, Yongli; Zhang, Xiaojun; Wei, Zhifu; Wang, Gen; Zhang, Ting; Ma, He; Wei, Jianteng; He, Wei; Ma, Xueyun; Zhu, Chenxi

doi:10.1016/j.gr.2022.01.008

Cited by 20 publications

(11 citation statements)

References 132 publications

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“…From the Douposi Formation, the depositional environment gradually changed to a carbonate platform (Figs. 1, 2; Fu et al 2020; Li et al 2021; Zhang et al 2022).…”

Section: Geological Settingmentioning

confidence: 99%

Paleo-trade wind directions over the Yangtze Carbonate Platform during the Cambrian–Ordovician, Southern China

Qin

et al. 2023

Geol. Mag.

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The Sichuan Basin was a part of the Yangtze Carbonate Platform (YCP) during the Cambrian–Ordovician, and marine carbonates were deposited in the basin during this interval. Although previous studies have evaluated the paleogeography, paleoclimate and paleoecology of this basin, they have primarily focused on the paleoecology and biological evolution in the basin; however, analysis of paleogeography and paleoclimate is lacking. This study integrated outcrop sedimentological and magnetic fabric data to document sedimentary differentiation and anisotropy of magnetic susceptibility (AMS) within the YCP. The aims of this study were to infer paleowind directions during each epoch of the Cambrian–Ordovician and to constrain the paleogeographic location of the YCP. The northwestern, central and southeastern sides of the YCP were characterized by high-energy deposition (e.g. sub-angular to rounded intraclasts), medium-energy deposition (e.g. sub-angular to sub-rounded intraclasts) and low-energy deposition (e.g. angular to sub-angular intraclasts), respectively. The centroid D-Kmax values for the Early, Middle and Late Cambrian were 116° ± 52°, 145° ± 57° and 159° ± 62° from the present north, respectively; corresponding values for the Early, Middle and Late Ordovician were 169° ± 70°, 139° ± 73° and 91° ± 68° from the present north, respectively. Sedimentary differentiation and AMS results indicated that the prevailing wind directions during the Early Cambrian, Middle Cambrian, Late Cambrian, Early Ordovician, Middle Ordovician and Late Ordovician were 296° ± 52°, 325° ± 57°, 339° ± 62°, 349° ± 70°, 319° ± 73° and 271° ± 68° from the present north, respectively. The present study provides evidence for the location of the YCP during the Cambrian–Ordovician via the correspondence between the paleowind directions over the YCP and the trade winds in the Northern and Southern hemispheres. The novelty of this study lies in the following aspects: (1) it integrates microfacies and AMS analyses to establish paleowind patterns; (2) it constrains the paleo-hemispheric location of the YCP during the Cambrian–Ordovician; and (3) it provides a reference for further studies of the paleoclimate and paleogeography of the YCP during the Cambrian–Ordovician.

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“…From the Douposi Formation, the depositional environment gradually changed to a carbonate platform (Figs. 1, 2; Fu et al 2020; Li et al 2021; Zhang et al 2022).…”

Section: Geological Settingmentioning

confidence: 99%

Paleo-trade wind directions over the Yangtze Carbonate Platform during the Cambrian–Ordovician, Southern China

Qin

et al. 2023

Geol. Mag.

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“…REEs are an effective indicator for recovering paleoenvironments (Figure 6d-f), but they are highly susceptible to terrigenous debris and late diagenesis [62]. In general, the mixing of terrigenous detrital materials leads to a significant increase in the ∑REE content [63,64]. The lower ∑REE of Cal-1 could represent a relatively pure meteoric freshwater environment.…”

Section: Characteristics Of Multi-period Meteoric Calcite Cementsmentioning

confidence: 99%

“…Elemental features can effectively identify the origin of authigenic minerals: in particular, the composition and distribution pattern of REE can precisely identify the fluid source [62,66]. The characteristics of Cal-1 are a complete euhedral form; a unique ring-shaped CL luminescent; Pattern-1; moderate CI, Fe, Mn, and Ba content; and low ∑REE all suggest that the meteoric fluid may have been polluted by few terrigenous (Figure 6; Table 2) [40,64]. Moreover, the fluid content was low; therefore, precipitation occurred only at the pore edges and not on a large scale.…”

Section: Characteristics Of Multi-period Meteoric Calcite Cementsmentioning

confidence: 99%

Controlling Factors of Meteoric Diagenesis in Karst Reservoirs: An Example from the Majiagou Formation, Ordos Basin, China

Yang

Zhang

et al. 2023

Minerals

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Karst reservoirs have always been a key field of oil and gas exploration. However, quantifying the process of meteoric transformation remains a persistent challenge that limits the accuracy of reservoir quality prediction. To explore the controlling factors of meteoric cementation on karst reservoirs, the Majiagou Formation of the Ordos Basin in China was selected as an example. The petrology; carbon, oxygen, and strontium isotopes; and in situ major, trace, and rare earth elements were used, types and origins of calcite cements were analyzed in detail. The results revealed five types of calcite cements (Cal-1~Cal-5), four types of cathodoluminescence (CL) intensities (dull, dull red, deep red, and bright red luminescence), and six types of rare earth element patterns (Pattern-1~Pattern-6). These five types of calcite cements developed in three periods. Cal-1 (transition CL) and Cal-2 (dull CL) were precipitated during the Early Pennsylvanian period, the meteoric freshwater was clean; Cal-3 (transition CL) and Cal-4 (bright red CL) were precipitated at the end of the Late Carboniferous period, the fluids had strong dissolution ability and were polluted by terrigenous debris; Cal-5 (transition CL) was deposited during the burial period, the fluid was pure pore water or groundwater. The control of the cement on the reservoir during the burial period was much weaker than that of meteoric cements. Therefore, explorations of karst reservoirs should be focused on weak cementation during the epigenetic period.

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“…The paleosedimentary environment plays a crucial role in organic matter (OM) enrichment, mineral composition, and pore system features. Consequently, the reconstruction of paleosedimentary environments holds significant importance for comprehending the mechanisms governing shale oil accumulation and identifying promising exploration targets [10,[20][21][22]. In geological history, the Jurassic emerges as a paradigmatic greenhouse period characterized by warm and humid conditions.…”

Section: Introductionmentioning

confidence: 99%

Geological Features, Paleosedimentary Environment, and Organic Matter Accumulation Mechanisms of the Lacustrine Shale Oil System: A Case Study of the Jurassic Dongyuemiao Member in the Sichuan Basin

Wang,

Li,

Guo

et al. 2023

Processes

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Lacustrine shale has garnered significant attention due to its significant resource potential. The Jurassic shale in the Sichuan Basin is an important target for lacustrine shale exploration in China. However, previous studies have predominantly focused on the Da’anzhai member of the Ziliujing Formation, and little attention has been paid to the shale of other strata. This paper aims to address this gap by investigating the Jurassic Dongyuemiao member in the Sichuan Basin. The study systematically characterizes the geological properties of the Dongyuemiao shale system, reconstructs the paleosedimentary environment, identifies the key factors influencing organic matter (OM) enrichment and physical properties, and assesses its resource potential through comparative analysis. Our results show that the Dongyuemiao shale was deposited in an oxic and semi-humid sedimentary environment characterized by intense weathering conditions. The enrichment of OM in the shale is primarily controlled by redox conditions and salinity, with redox conditions playing the most crucial role in OM accumulation. In terms of pore system characterization, clay mineral-associated pores dominate the pore types in the Dongyuemiao shale, while two types of organic matter-associated pores are also widely observed. The development of framework grain-associated pores is limited and only present in certain siliceous and carbonate minerals. The shales of the Dongyuemiao member and the Da’anzhai member exhibit slight differences in TOC content. However, the kerogen in the Dongyuemiao member displays higher hydrocarbon generation potential, and the Dongyuemiao shale exhibits more favorable pore structure parameters. Overall, the Dongyuemiao shale does not exhibit any significant disadvantages compared to the Da’anzhai shale. Therefore, it deserves greater attention in future exploration endeavors. The research findings presented in this paper provide a solid theoretical foundation for expanding the exploration scope of lacustrine shale in the Sichuan Basin.

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Carbon, oxygen and strontium isotopic and elemental characteristics of the Cambrian Longwangmiao Formation in South China: Paleoenvironmental significance and implications for carbon isotope excursions

Cited by 20 publications

References 132 publications

Paleo-trade wind directions over the Yangtze Carbonate Platform during the Cambrian–Ordovician, Southern China

Paleo-trade wind directions over the Yangtze Carbonate Platform during the Cambrian–Ordovician, Southern China

Controlling Factors of Meteoric Diagenesis in Karst Reservoirs: An Example from the Majiagou Formation, Ordos Basin, China

Geological Features, Paleosedimentary Environment, and Organic Matter Accumulation Mechanisms of the Lacustrine Shale Oil System: A Case Study of the Jurassic Dongyuemiao Member in the Sichuan Basin

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