Morphologies, classification and genesis of pockmarks, mud volcanoes and associated fluid escape features in the northern Zhongjiannan Basin, South China Sea

Chen, Jiangxin; Song, Haibin; Guan, Yanan; Yang, Shengxiong; Pinheiro, Luís Menezes; Bai, Yang; Liu, Boran; Geng, Minghui

doi:10.1016/j.dsr2.2015.11.007

Cited by 67 publications

(43 citation statements)

References 54 publications

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“…It seems that the heat flow of Xisha uplift largely succeeded the increasing tendency of the QDNB from north to south, and continued to increase in the southeast Xisha uplift, indicating that Xisha uplift also have heat flow elevated above the expected background level. Compared with mud volcanoes developed in basins like the ZJNB, which have thick sediments (e.g. Sun et al, ; Chen et al, ), they are substantially less likely to form in the Xisha uplift because of a much thinner sediment cover than those of adjacent basins (Figure c). The largest mud volcano reported in the northern ZJNB has 2.29 km in diameter and 213.5 m height.…”

Section: Discussionmentioning

confidence: 97%

“…Mud volcanoes have been found in the northern ZJNB, which is close to the Xisha uplift in the south (Chen et al, ; Sun et al, ). Both mud and magmatic volcanoes appear in the multibeam bathymetric maps and the seismic images with similar external shapes, such as circular or elliptical cones, and chaotic seismic reflections.…”

Section: Discussionmentioning

confidence: 98%

“…gas hydrate) or seabed hazards in the northern and western margin of the SCS, such as the Yinggehai Basin (YGHB), Pearl River Mouth Basin (PRMB), Qiongdongnan Basin (QDNB) and Zhongjiannan Basin (ZJNB, also called Phu Khanh Basin; Chen et al, ; Lei et al, ; Sun, Wu, Cartwright, & Dong, ; Sun et al, ; Sun et al, ; Wan et al, ; Wang et al, ). These studies attributed such features to local fluid overpressure, driven by deep thermogenic fluid flow from source rocks or gas reservoirs during post‐rifting thermal subsidence (Chen et al, ; Sun et al, ; Wan et al, ; Wang et al, ), or shallow biogenic fluid flow within soft sediments (Sun et al, ). However, none of these authors have considered the magmatically induced fluid flows (magmatic hydrothermal systems) since the post‐seafloor spreading magmatic activity intensely occurred in the northwestern SCS.…”

Section: Introductionmentioning

confidence: 99%

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Post‐seafloor spreading magmatism and associated magmatic hydrothermal systems in the Xisha uplift region, northwestern South China Sea

Gao

Bangs

et al. 2019

Basin Research

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Submarine magmatism and associated hydrothermal fluid flows has significant feedback influence on the petroleum geology of sedimentary basins. This study uses new seismic profiles and multibeam bathymetric data to examine the morphology and internal architecture of post-seafloor spreading magmatic structures, especially volcanoes of the Xisha uplift, in extensive detail. We discover for the first time hydrothermal systems derived from magmatism in the northwestern South China Sea. Numerous solitary volcanoes and volcanic groups occur in the Xisha uplift and produce distinct seismic reflections together with plutons. Sills and other localized amplitude anomalies were fed by extrusions/intrusions and associated fluid flow through fractures and sedimentary layers that may act as conduits for magma and fluid flows transport. Hydrothermal structures such as pipes and pockmarks mainly occur in the proximity of volcanoes or accompany volcanic groups. Pipes, pockmarks and localized amplitude anomalies mainly constitute the magmatic hydrothermal systems, which are probably driven by post-seafloor spreading volcanoes/plutons. The hydrothermal fluid flows released by magma degassing or/and related boiling of pore fluids/metamorphic dehydration reactions in sediments produced local overpressures, which drove upward flow of fluid or horizontal flow into the sediments or even seafloor. Results show that post-seafloor spreading magmatic activity is more intense during a 5.5 Ma event than one in 2.6 Ma, whereas the hydrothermal activities are more active during 2.6 Ma than in 5.5 Ma. Our analysis indicates that post-seafloor spreading magmatism may have a significant effect on hydrocarbon maturation and gas hydrate formation in the Xisha uplift and adjacent petroliferous basins. Consequently the study presented here improves our understanding of hydrocarbon exploration in the northwestern South China Sea. K E Y W O R D S hydrothermal fluid flows, NW South China Sea, post-seafloor spreading magmatism, Xisha uplift | 689 EAGE GAO et Al. 692 | EAGE GAO et Al. the top of the Huangliu formation, is the boundary of late Miocene and Pliocene (about 5.5 Ma).

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Post‐seafloor spreading magmatism and associated magmatic hydrothermal systems in the Xisha uplift region, northwestern South China Sea

Gao

Bangs

et al. 2019

Basin Research

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“…This divergence occurred after the Cretaceous-Palaeogene mass extinction, which was followed by an explosive radiation of organisms [41]. And this time is nearly contemporaneous with the early basement-forming stage of Zhongjiannan Basin [35,42], suggesting that G. gigas was an invasive species in this basin. It has been proposed that deep-water barnacles originated from shallow waters [40,43], and comparison with shallow-water barnacles might help explain how deep-sea barnacles have adapted to the harsh conditions on the deep-sea floor which characterized by high hydrostatic pressure, darkness, hypoxia, low temperature, and limited food availability.…”

Section: Discussionmentioning

confidence: 99%

“…Zhongjiannan Basin is a Cenozoic sedimentary basin located in the narrowest part of the South China Sea shelf with depths extending down to 4000 m [33,34]. In the northern area of Zhongjiannan Basin, specific geological structures, including mud volcanoes and pockmarks, are common on the seafloor [35,36]. Comparing genetic information between these two species could help explain how G. gigas has migrated and adapted to this complex environment.…”

Section: Introductionmentioning

confidence: 99%

Comparative transcriptomic analysis of deep- and shallow-water barnacle species (Cirripedia, Poecilasmatidae) provides insights into deep-sea adaptation of sessile crustaceans

et al. 2020

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Background: Barnacles are specialized marine organisms that differ from other crustaceans in possession of a calcareous shell, which is attached to submerged surfaces. Barnacles have a wide distribution, mostly in the intertidal zone and shallow waters, but a few species inhabit the deep-sea floor. It is of interest to investigate how such sessile crustaceans became adapted to extreme deep-sea environments. We sequenced the transcriptomes of a deep-sea barnacle, Glyptelasma gigas collected at a depth of 731 m from the northern area of the Zhongjiannan Basin, and a shallow-water coordinal relative, Octolasmis warwicki. The purpose of this study was to provide genetic resources for investigating adaptation mechanisms of deep-sea barnacles.Results: Totals of 62,470 and 51,585 unigenes were assembled for G. gigas and O. warwicki, respectively, and functional annotation of these unigenes was made using public databases. Comparison of the protein-coding genes between the deep-and shallow-water barnacles, and with those of four other shallow-water crustaceans, revealed 26 gene families that had experienced significant expansion in G. gigas. Functional annotation showed that these expanded genes were predominately related to DNA repair, signal transduction and carbohydrate metabolism. Base substitution analysis on the 11,611 single-copy orthologs between G. gigas and O. warwicki indicated that 25 of them were distinctly positive selected in the deep-sea barnacle, including genes related to transcription, DNA repair, ligand binding, ion channels and energy metabolism, potentially indicating their importance for survival of G. gigas in the deep-sea environment.(Continued on next page) Conclusions: The barnacle G. gigas has adopted strategies of expansion of specific gene families and of positive selection of key genes to counteract the negative effects of high hydrostatic pressure, hypoxia, low temperature and food limitation on the deep-sea floor. These expanded gene families and genes under positive selection would tend to enhance the capacities of G. gigas for signal transduction, genetic information processing and energy metabolism, and facilitate networks for perceiving and responding physiologically to the environmental conditions in deep-sea habitats. In short, our results provide genomic evidence relating to deep-sea adaptation of G. gigas, which provide a basis for further biological studies of sessile crustaceans in the deep sea.

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Increased Fluid Flow Activity in Shallow Sediments at the 3 km Long Hugin Fracture in the Central North Sea

Lichtschlag

Cevatoglu

Connelly

et al. 2018

Geochem Geophys Geosyst

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The North Sea hosts a wide variety of seafloor seeps that may be important for transfer of chemical species, such as methane, from the Earth's interior to its exterior. Here we provide geochemical and geophysical evidence for fluid flow within shallow sediments at the recently discovered, 3 km long Hugin Fracture in the Central North Sea. Although venting of gas bubbles was not observed, concentrations of dissolved methane were significantly elevated (up to six‐times background values) in the water column at various locations above the fracture, and microbial mats that form in the presence of methane were observed at the seafloor. Seismic amplitude anomalies revealed a bright spot at a fault bend that may be the source of the water column methane. Sediment porewaters recovered in close proximity to the Hugin Fracture indicate the presence of fluids from two different shallow (<550 m) sources: (i) a reduced fluid characterized by elevated methane concentrations and/or high levels of dissolved sulfide (up to 6 mmol L−1), and (ii) a low‐chlorinity fluid (Cl ∼305 mmol L−1) that has low levels of dissolved methane and/or sulfide. The area of the seafloor affected by the presence of methane‐enriched fluids is similar to the footprint of seepage from other morphological features in the North Sea.

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Morphologies, classification and genesis of pockmarks, mud volcanoes and associated fluid escape features in the northern Zhongjiannan Basin, South China Sea

Cited by 67 publications

References 54 publications

Post‐seafloor spreading magmatism and associated magmatic hydrothermal systems in the Xisha uplift region, northwestern South China Sea

Post‐seafloor spreading magmatism and associated magmatic hydrothermal systems in the Xisha uplift region, northwestern South China Sea

Comparative transcriptomic analysis of deep- and shallow-water barnacle species (Cirripedia, Poecilasmatidae) provides insights into deep-sea adaptation of sessile crustaceans

Increased Fluid Flow Activity in Shallow Sediments at the 3 km Long Hugin Fracture in the Central North Sea

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