Identification of multiple magnetizations of the Ediacaran strata in South China

Jing, Xianqing; Yang, Zhenyu; Tong, Yabo; Wang, Heng; Ying, Xu

doi:10.1093/gji/ggx396

Cited by 9 publications

(17 citation statements)

References 72 publications

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“…Unlike the widely recorded Late Mesozoic remagnetization in South China (e.g., Dobson & Heller, ; Evans et al, ; Gao et al, ; Huang et al, ; Huang & Opdyke, ; Jing et al, ; Jing et al, ; Kent et al, ; Zhang et al, ), a Triassic overprint was previously reported by only a few studies (Jiao et al, ; Zhang et al, ). Zhang et al () reported a Late Triassic (T 3 ) remagnetization from Sichuan, western South China, and Jiao et al () recently reported an Early‐Middle Triassic (T 1–2 ) remagnetization component from Zhejiang, eastern South China.…”

Section: Discussionmentioning

confidence: 78%

“…This age constraint on the timing of folding, however, is too crude to definitively conclude that the positive fold tests of the HTC indicate a primary remanence. Indeed, pre‐Jurassic remagnetization has been increasingly recognized in South China recently (e.g., Jiao et al, ; Jing et al, ; S. Zhang et al, ; Y. Zhang et al, ; Y. Zhang et al, ). As such, we compare the paleomagnetic pole of the HTC with the apparent polar wander path of South China.…”

Section: Discussionmentioning

confidence: 99%

“…While we are aiming to obtain a detailed paleomagnetic record from the relatively more expanded Late Cambrian succession from the Wa'ergang section to test and examine the Late Cambrian TPW in this study, we are fully aware of the extensive Mesozoic remagnetization that has been previously reported in South China (e.g., Dobson & Heller, ; Gao et al, ; Huang & Opdyke, ; Jing et al, ; Kent et al, ; Liu et al, ; Wang & Van der Voo, ; Zhang et al, ; Zhang et al, ). Although various remagnetization mechanisms have also been proposed (e.g., Gao et al, ; Huang & Opdyke, ; Jing et al, ; C. Liu, Ge, et al, ; Liu et al, ; Zhang et al, ), most previous studies focused on local processes leading to remagnetization. Few studies investigated the temporal‐spatial features of the remagnetization and the underlying mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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A Widespread Early Mesozoic Remagnetization in South China

Jiao

Yang

et al. 2019

JGR Solid Earth

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The recent discovery of a possible Late Cambrian true polar wander (TPW) from the Jiangshan section in eastern South China has intrigued us to test this TPW in other continuous, well-dated Upper Cambrian successions. We have conducted a detailed paleomagnetic study of a continuous Upper Cambrian succession in Wa'ergang, Hunan Province, middle South China, that contains well-defined trilobite zones correlative with those of the Jiangshan section. Three remanence components were isolated from the Upper Cambrian limestone. The low-and intermediate-temperature components represent a recent viscous magnetization and a Cretaceous remagnetization, respectively. The high-temperature component passes fold tests, but its pole lies close to the Middle Triassic pole of South China, indicating a Middle Triassic remagnetization.Rock magnetic analyses and petrographic observations indicate that the high-temperature component resides in small framboidal magnetite aggregates that were formed via alteration and replacement of pyrite and represents a chemical remagnetization. This Middle Triassic remagnetization and previously recognized Triassic remagnetization exhibit a younging trend from the east to the west of South China. The widespread Triassic remagnetization was likely associated with the Indosinian orogeny during which the scissor-like suturing processes between the South and North China Blocks and the accompanying so-called squeegeed orogenic fluids led to progressively westward younging remagnetization in South China. Although the new paleomagnetic results do not allow us to effectively test the Late Cambrian TPW due to the thorough remagnetization, these data provide important insights into understanding the Early Mesozoic remagnetization and associated geological processes.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Widespread Early Mesozoic Remagnetization in South China

Jiao

Yang

et al. 2019

JGR Solid Earth

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“…Most of these carbonate units host hydrocarbons (Figure a; Zhai, ), with giant oil or gas fields being located mainly in the Sichuan Basin in the Upper Yangtze block and with oil‐ or bitumen‐bearing outcrops occurring along the western and northern margins of the Jiangnan‐Xuefeng orogen (Figure a; Ge et al, ; Li et al, ). Among these reservoir units, the oldest and most important is the Ediacaran dolomite, which hosts the single largest carbonate gas reservoir in China, that is, the Anyue Gas Field (Figure a), and possibly shows chemical remagnetization (Jing et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

“…Depending on the exact conditions, these models predict that magnetic minerals present will be either iron sulfides, iron oxides, or siderite. For hydrocarbon‐related remagnetization in carbonate systems, authigenic magnetite has been found to be the most common magnetic mineral (e.g., Elmore et al, ; Elmore & Crawford, ; Jing et al, ; Katz et al, ). In contrast, authigenic iron sulphides are not usually reported as the main magnetic minerals in hydrocarbon‐impregnated carbonates (Font et al, ) but have been reported in hydrocarbon‐bearing red beds (Reynolds et al, ), oil‐saturated sandstone (Kilgore & Elmore, ), organic‐rich shale (Manning & Elmore, ), and pyrolysis experiments (Abubakar et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Chemical Remagnetization of Ediacaran Dolomite in the Taishan Paleo‐Reservoir, South China

et al. 2018

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To understand the origin of chemical remagnetization in carbonate reservoir rocks and associated chemical processes, we have conducted detailed petrologic, geochemical, and magnetic studies of the hydrocarbon‐impregnated Ediacaran dolomite in the Taishan Paleo‐reservoir, south China. Samples were collected across a continuous outcrop consisting of oil‐free dolomite, transition zone dolomite, and highly hydrocarbon‐impregnated reservoir dolomite. Paleomagnetic results show that dolomite from the reservoir and transition zone were remagnetized and carries a possible Cambrian‐Ordovician direction (Dec = 163.7°, Inc = 10.6°, and α95 = 1.9°), and the oil‐free dolomite shows unstable magnetizations. Hematite is the magnetic mineral in the oil‐free dolomite, whereas the hydrocarbon‐impregnated reservoir dolomite contains no hematite but mainly pyrrhotite nanoparticles. Transition‐zone dolomite contains both hematite and pyrrhotite. In addition, the natural remanent magnetization intensities decrease from the reservoir dolomite, through the transition zone, and into the oil‐free dolomite, and a similar trend was observed in the total organic carbon and bitumen contents. The results suggest that the magnetic mineral assemblage and magnetic intensity in dolomite appear to be closely related to the degree of hydrocarbon impregnation and that remagnetization of the Ediacaran dolomite was likely caused by hydrocarbon migration into the dolomite. Pyrrhotite nanoparticles, magnetite, and barite are suggested to be formed during hydrocarbon migration, by the reduction of detrital hematite in the dolomite and sulfur species in the hydrocarbons. The new findings into the origin of pervasive remagnetization have the potential to guide future hydrocarbon exploration within Ediacaran dolomite that is host to the largest single carbonate gas reservoir in China.

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