Constraints of fluid inclusions and C, O isotopic compositions on the origin of the dolomites in the Xisha Islands, South China Sea

Bi, Dongjie; Zhai, Shikui; Zhang, Daojun; Liu, Xiaofeng; Li, Xinyu; Jiang, Longjie; Zhang, Aibin

doi:10.1016/j.chemgeo.2018.07.005

Cited by 23 publications

(21 citation statements)

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“…Well “Xike‐1” has been isolated from the main continent since the formation of the Xisha Block during the early Cenozoic (Shao et al, ). Bi et al (), Wang et al (), and Shao et al () comprehensively described the petrographic and biostratigraphic characteristics of the “Xike‐1” reef core. Hence, only a brief summary is provided here.…”

Section: Samples and Analytical Methodsmentioning

confidence: 99%

“…The Xisha Islands (17°07′‐15°43′ N, 111°11′‐112°54′ E) are located on an elevated submarine plateau, which rises from the lower slope southeast of Hainan Island. Scientific and commercial drilling programs conducted in the 1970s and 1980s provided extensive data describing the biostratigraphy, lithology, sedimentology, paleomagnetism, and seismology of the islands, as well as information about the morphology of their biota (Wang, He, & Qiu, ; Zhang, Liu, & Zhou, ; Liu, Ye, Han, Liu, & Qu, ; Shi, Zhou, Qiu, & Zhang, ; Zhao, 2010; Bi et al, ). However, these early boreholes are limited in their utility due to incomplete core recovery and a lack of basement drilling.…”

Section: Geologic Settingmentioning

confidence: 99%

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Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Zhang

Zhai

et al. 2018

Geological Journal

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Reef carbonates represent a practical option for continuous sampling in seawater 87Sr/86Sr values studies. A study of Sr isotopes is carried out for reef carbonates from the well “Xike‐1”, Shi Island, Xisha Islands, with the purpose of reconstructing the changing process of seawater 87Sr/86Sr values since the Neogene in the South China Sea (SCS). The results provide insights into the impact of paleoclimatic and paleoenvironmental factors on the seawater 87Sr/86Sr values in the SCS. Our study indicates that the 87Sr/86Sr values in reef carbonates have increased since the Neogene. Those variation process can be divided into three stages, which are the fluctuant rising stage (Early Miocene to Middle Miocene), the steady rising stage (Middle Miocene to Late Miocene), and the fluctuating stage (Pliocene to Quaternary), respectively. The change of terrigenous influx is the main factor controlling seawater 87Sr/86Sr values in the SCS. The 87Sr/86Sr values in reef carbonates are slightly higher than that in the coeval seawater, which reflects a semiclosed environment of the SCS relative to the open ocean. The variations of seawater 87Sr/86Sr values and terrigenous influx in the SCS have no obvious correspondence with the changes of seawater δ18O values recorded by the benthonic foraminiferal skeletons in the drilling core of ODP site 1148. Thus, paleoclimatic factor is unlikely to be the dominant factor for the changes of terrigenous influx in the study area. However, there is a good correspondence between the variation rates of the 87Sr/86Sr values, the accumulation rates of terrigenous materials, and the uplifting rates of the Qinghai‐Tibet Plateau. This indicates that the changes of terrigenous influx should be caused by enhancement of erosion, weathering, or transportation linked to the tectonic activities. The uplift of the Qinghai‐Tibet Plateau and the variations of uplifting rates should be the main factor controlling the variations of the terrigenous influx in the SCS, which would further influence the seawater 87Sr/86Sr values.

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Section: Samples and Analytical Methodsmentioning

confidence: 99%

Section: Geologic Settingmentioning

confidence: 99%

Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Zhang

Zhai

et al. 2018

Geological Journal

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“…To our knowledge, no gas hydrates have been found in the Xisha area, despite the BSRs, porewater characteristics and the occurrence of pockmarks suggest a great resource potential [20][21][22]. During the last decades, numerous studies have been conducted in this area, but their attention was mainly focused on the formation of carbonates and their paleoclimate evolution [23,24], and no direct investigation on the organic geochemical evidence related to a source indication for verifying the existence of petroleum/gas reservoirs and gas hydrates in the Xisha area has been reported. Therefore, we still do not clearly know the characteristics of sedimentary organic matter in this area, which may provide important information for identifying gas hydrate and petroleum/gas reservoirs.…”

Section: Introductionmentioning

confidence: 95%

Source Indication and Geochemical Significance of Sedimentary Organic Matters from the Xisha Area, the South China Sea

Zhou

et al. 2021

Molecules

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Although various geochemical and geophysical investigations have already indicated a great resource potential in the Xisha area of the South China Sea, the origin of organic matter and molecular evidence for tracing the migration of hydrocarbons from deep petroleum reservoirs are still lacking. In this study, systematic organic geochemical analyses, including bulk organic matter parameters and lipid biomarkers were performed for deep sediments from two cores. The C/N ratios and δ13C and δ15N values of organic matter in most of the samples, together with the maxima of short-chain n-alkanoic acids and mid-chain n-alkanols, high abundances of monounsaturated fatty acids C18:1ω9 and C22:1ω13, jointly indicate the dominance of marine organic matter. n-Alkanes in sediments from core GMGS4-XH-W06B are characterized by small unresolved complex mixture (UCMs) humps, high odd/even predominance (OEP) and carbon preference index (CPI) values, clearly exhibiting characteristics of modern sediments. However, the sediments for core GMGS4-XH-W03B are featured with big UCMs, associated with OEP and CPI values around 1.0, showing signatures of petroleum hydrocarbons from high maturity sources. Considering the geologic background, the biomarker signatures are solid evidence for indicating the existence of underlying petroleum reservoirs, and may provide the valuable information for assessing the hydrocarbon resources in the Xisha area.

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“…Data of submerged speleothems, marine overgrowth, and phreatic overgrowth are from coastal caves of Belize, Eastern Adriatic Coast, and Mallorca (Surićet al, 2005;Tuccimei et al, 2010;Gischler et al, 2017). The mean values of the calcite from Xisha Islands are adopted from Bi et al (2018).…”

mentioning

confidence: 99%

Deep submerged speleothems in the Sansha Yongle Blue Hole (South China Sea) as determination of low sea levels during the Last Glacial Maximum

Duan

Zhao

et al. 2022

Front. Mar. Sci.

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Although Last Glacial Maximum (LGM) sea levels have been the focus of much attention in climate and marine sciences, the timing, duration, and magnitude need further research. Here we present observations and analyses of the deepest speleothems (-116 m) collected from the deepest known blue hole on a global scale, the Sansha Yongle Blue Hole, Xisha Islands, South China Sea. The field investigations illustrate that submerged speleothems are irregular cauliflower-like coatings on the downward cave ceiling from water depths of ~90 to 120 m. The downward growth direction and negative stable carbon and oxygen stable isotopes of submerged speleothems suggest that they may deposit in an air-filled condition through gravity drip, indicating the maximum LGM sea level. The deep submerged speleothems were dated, indicating two U–Th ages of 29.16 ± 0.17 and 26.04 ± 0.18 ka BP and one radiocarbon age of 18.64 ± 0.12 ka BP, respectively. The investigated deep submerged speleothems therefore clearly determine the minimum onset and maximum termination times for LGM terms of sea level. The results show that LGM began at ~29 ka BP and ended at ~18.5 ka BP. This study therefore provides initial evidence for the use of deep speleothems to determine LGM sea levels and emphasizes the importance of deep submerged speleothems in the reconstruction of Pleistocene low sea levels.

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Constraints of fluid inclusions and C, O isotopic compositions on the origin of the dolomites in the Xisha Islands, South China Sea

Cited by 23 publications

References 58 publications

Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Source Indication and Geochemical Significance of Sedimentary Organic Matters from the Xisha Area, the South China Sea

Deep submerged speleothems in the Sansha Yongle Blue Hole (South China Sea) as determination of low sea levels during the Last Glacial Maximum

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Constraints of fluid inclusions and C, O isotopic compositions on the origin of the dolomites in the Xisha Islands, South China Sea

Cited by 23 publications

References 58 publications

Seawater 87Sr/86Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Seawater 87Sr/86Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Source Indication and Geochemical Significance of Sedimentary Organic Matters from the Xisha Area, the South China Sea

Deep submerged speleothems in the Sansha Yongle Blue Hole (South China Sea) as determination of low sea levels during the Last Glacial Maximum

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Product

Resources

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Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau

Seawater ⁸⁷Sr/⁸⁶Sr values recorded by reef carbonates from the Xisha Islands (South China Sea) since the Neogene and its response to the uplift of Qinghai‐Tibetan Plateau