Seismic Characterization of Hypogenic Karst Systems Associated with Deep Hydrothermal Fluids in the Middle-Lower Ordovician Yingshan Formation of the Shunnan Area, Tarim Basin, NW China

Zhu, Hongtao; Zhu, Xiaomin; Chen, Honghan

doi:10.1155/2017/8094125

Cited by 14 publications

(5 citation statements)

References 33 publications

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“…As an example, venting of subcrustal CO 2 has been described in a hydrothermal cave associated with an active, deep-rooted fault [13]. Recent works deal with the importance of seismic characterization of these systems since faults act as preferential migration routes of the ascending fluids that contribute to the formation of the hypogenic karstic system [14].…”

Section: Introductionmentioning

confidence: 99%

Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

et al. 2018

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The hydrothermal caves linked to active faulting can potentially harbour subterranean atmospheres with a distinctive gaseous composition with deep endogenous gases, such as carbon dioxide (CO2) and methane (CH4). In this study, we provide insight into the sourcing, mixing, and biogeochemical processes involved in the dynamic of deep endogenous gas formation in an exceptionally dynamic hypogenic karst system (Vapour Cave, southern Spain) associated with active faulting. The cave environment is characterized by a prevailing combination of rising warm air with large CO2 outgassing (>1%) and highly diluted CH4 with an endogenous origin. The δ13CCO2 data, which ranges from −4.5 to −7.5‰, point to a mantle-rooted CO2 that is likely generated by the thermal decarbonation of underlying marine carbonates, combined with degassing from CO2-rich groundwater. A pooled analysis of δ13CCO2 data from exterior, cave, and soil indicates that the upwelling of geogenic CO2 has a clear influence on soil air, which further suggests a potential for the release of CO2 along fractured carbonates. CH4 molar fractions and their δD and δ13C values (ranging from −77 to −48‰ and from −52 to −30‰, respectively) suggest that the methane reaching Vapour Cave is the remnant of a larger source of CH4, which was likely generated by microbial reduction of carbonates. This CH4 has been affected by a postgenetic microbial oxidation, such that the gas samples have changed in both molecular and isotopic composition after formation and during migration through the cave environment. Yet, in the deepest cave locations (i.e., 30 m below the surface), measured concentration values of deep endogenous CH4 are higher than in atmospheric with lighter δ13C values with respect to those found in the local atmosphere, which indicates that Vapour Cave may occasionally act as a net source of CH4 to the open atmosphere.

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Section: Introductionmentioning

confidence: 99%

Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

et al. 2018

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“…Meanwhile, there is almost no porosity in slightly silicified limestone (Figure 4g), no direct evidence shows the existence of primary pores or early secondary pores in slightly silicified limestone. Furthermore, as introduced earlier, the silicification in the SN area was caused by hydrothermal fluids (H. H. Chen et al, 2016; J. Han et al, 2016; Li et al, 2015, 2017; Lu et al, 2017; Qi, 2016; You et al, 2018; X. Zhu et al, 2016), and the timing of the hydrothermal silicification is constrained from the Late Ordovician to Late Permian (Figure 3). During hydrothermal silicification event, the burial depth of the Lower–Middle Ordovician carbonates was more than 3,000 m and their stratum temperature was higher than 120°C, representing a deep burial condition.…”

Section: Discussion: Hydrothermal Silicification Enhanced Reservoir P...mentioning

confidence: 88%

“…The Well SN4 is one of the most productive wells in the SN area, and most of the secondary pores are developed in the strongly silicified limestone/chert of the Ordovician Yingshan Formation, at a depth of more than 6,000 m (J. Han et al, 2014; Huang, 2014). Numerous researchers interpreted that the silicification is of hydrothermal origin (H. H. Chen, Lu, Cao, Han, & Yun, 2016; J. Han, Cao, Qiu, You, & Zhang, 2016; Li et al, 2015, 2017; Lu et al, 2017; Qi, 2016; You et al, 2018; X. Zhu et al, 2016). They proposed that the secondary porosity in the strongly silicified limestone/chert was formed by the silicification which significantly enhanced reservoir properties of the deeply buried carbonates (H. H. Chen et al, 2016; J. Han et al, 2016; Qi, 2016; X. Zhu et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Numerous researchers interpreted that the silicification is of hydrothermal origin (H. H. Chen, Lu, Cao, Han, & Yun, 2016; J. Han, Cao, Qiu, You, & Zhang, 2016; Li et al, 2015, 2017; Lu et al, 2017; Qi, 2016; You et al, 2018; X. Zhu et al, 2016). They proposed that the secondary porosity in the strongly silicified limestone/chert was formed by the silicification which significantly enhanced reservoir properties of the deeply buried carbonates (H. H. Chen et al, 2016; J. Han et al, 2016; Qi, 2016; X. Zhu et al, 2016). The silicification is interpreted to be emplaced during the Silurian‐Devonian (You et al, 2018), the Late Devonian (Lu et al, 2017; Qi, 2016), and the Permian (Li et al, 2015), that is, the silicification was emplaced later than that the carbonates buried to 3,000 m. However, it is not well documented whether the silicification created new secondary pores during deep burial diagenesis (>3,000 m) or the silicified limestone inherits the precursor pores during the silicification.…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal silicification and its impact on Lower–Middle Ordovician carbonates in Shunnan area, Tarim Basin, NW China

Huang

et al. 2022

Geological Journal

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The Shunnan area is a newly discovered hydrocarbon field in Shuntuoguole lower uplift, in which the host rocks are Lower–Middle Ordovician carbonates. The carbonate reservoirs are well affected by hydrothermal silicification with well‐preserved intercrystalline pore of replacement quartz and megaquartz cements. Based on the petrography, pore types, and diagenetic processes, this research evaluated the reservoir quality and re‐constructed the porosity evolution in different diagenetic stages. Samples are collected from 7‐cored wells distributed along NNE‐ or ENE‐trending sinistral strike‐slip faults. Nine types of lithofacies were identified in the study area, including mudstone, bioclast wackestone, peloidal bioclast packstone, boundstone, peloidal grainstone, ooid grainstone, slightly silicified limestone (silica less than 25%), strongly silicified limestone (silica around 50%), and chert. Chert has better porosity (average 21.3%) and permeability (average 44.7 mD) than other lithofacies. The main reservoir pores are mainly developed in forms of fractures, intercrystalline replacement quartz and dissolved vugs. The porosity evolution shows that the primary porosity was limited due to cementation and compaction, and the earlier secondary porosity was occlusive as a result of coarse calcite cementation. Therefore, the precursor limestones may be tight, and the reservoir quality of the Lower–Middle Ordovician carbonates was controlled by hydrothermal silicification. During the hydrothermal silicification event, the burial depth of the Lower–Middle Ordovician carbonates was more than 3,000 m and their stratum temperature was higher than 120°C, representing a deep burial condition. The statistical data of porosity‐depth/temperature trends for carbonates suggest that the early secondary pores would be significantly reduced when the burial temperature reaches 100°C (or depth of strata reaches 3,000 m). Therefore, the dissolved vugs in strongly silicified limestone or hydrothermal chert are caused by hydrothermal silicification and not inherited from precursor carbonate rocks.

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“…the gradient from island freshwater lens and mixing zone flank margin caves; Micallef et al, 2021; Micallef, Person, et al, 2021; Mylroie & Carew, 1990; Mylroie et al, 1995) and hypogenic fluids (e.g. Zhu et al, 2017) to the dissolution features is also possible.…”

Section: Discussionmentioning

confidence: 99%

Stratigraphic evolution and karstification of a Cretaceous Mid‐Pacific atoll (Resolution Guyot) resolved from core‐log‐seismic integration and comparison with modern and ancient analogues

2022

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Atolls are faithful recorders helping us understand eustatic variations, the evolution of carbonate production through time, and changes in magmatic hotspots activity. Several early Cretaceous Mid-Pacific atolls were previously investigated through ocean drilling, but due to the low quality of vintage seismic data available, few spatial constraints exist on their stratigraphic evolution and large-scale diagenesis. Here, we present results from an integrated core-log-seismic study at Resolution Guyot and comparison with modern and ancient analogues. We EAGE EL-YAMANIetal.

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Seismic Characterization of Hypogenic Karst Systems Associated with Deep Hydrothermal Fluids in the Middle-Lower Ordovician Yingshan Formation of the Shunnan Area, Tarim Basin, NW China

Cited by 14 publications

References 33 publications

Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

Hydrothermal silicification and its impact on Lower–Middle Ordovician carbonates in Shunnan area, Tarim Basin, NW China

Stratigraphic evolution and karstification of a Cretaceous Mid‐Pacific atoll (Resolution Guyot) resolved from core‐log‐seismic integration and comparison with modern and ancient analogues

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