Geochemistry of black shale at the bottom of the Lower Cambrian in Tarim Basin and its significance for lithosphere evolution

Yu, Bingsong; Chen, Jianqiang; Xingwu, LI; Lin, Changsong

doi:10.1360/03yd9043

Cited by 19 publications

(16 citation statements)

References 10 publications

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“…No Cambrian magmatic records have been discovered in the northern Tarim Craton except for minor basalts of the Xishanbulake Formation in the Kuruktagh area, NE Tarim (Jiang, Bai, Hei, Zhao, & Zhang, ; Li et al, ; Xia, Xia, Xu, Li, & Ma, ). Our new pyroxene 40 Ar/ 39 Ar age probably reveals the first Cambrian magmatic record in the Aksu–Wushi area, and this is supported by geochemical compositions of the Cambrian black phosphorite shale from the Aksu–Wushi area which suggests an active source of mafic material during its deposition (Turner, ; Yu, Chen, Li, & Lin, ).…”

Section: Discussionsupporting

confidence: 60%

⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

Zhu

Jourdan

et al. 2018

Geological Journal

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Mafic dyke swarms and continental flood basalts record crucial information on mantle dynamics, crustal palaeostress, and supercontinent cycle. However, these mafic rocks are relatively difficult to date using zircon U–Pb methods because autogenous magmatic zircons are rare or absent in the rapidly cooled mafic magmas and most zircons extracted from these rocks are likely captured from their wall rocks. One good example of this dilemma is the Precambrian mafic dykes and layered basites in the Aksu–Wushi area, NW Tarim Craton, from which abundant zircon U–Pb data have yielded age spectra similar to those of the detrital zircons from the associated (meta‐)sedimentary rocks. In this paper, we performed the first 40Ar/39Ar dating on separated mineral grains from the mafic dykes (plagioclase and amphibole) and layered basites (plagioclase and pyroxene) in this area. Amphiboles from a mafic dyke cross‐cutting the blueschist‐bearing Aksu Group yielded a 40Ar/39Ar plateau age of 744.5 ± 2.8 Ma, whereas pyroxenes from a layered basite within the Sugetbrak Formation yielded a 40Ar/39Ar plateau age of 521.0 ± 2.1 Ma. The 40Ar/39Ar plateau age of 744.5 ± 2.8 was interpreted as the crystallization age of the studied mafic dykes and provides a minimum constraint for the third phase of deformation of the blueschist terrane. The mini‐plateau age of 521.0 ± 2.1 Ma was interpreted as a minimum crystallization age for basite of the Sugetbrak Formation. We also conducted geochemical analyses on layered basites of the Sugetbrak Formation from the Xiaoenbrak Formation, and the results indicated that these layered basites shared a uniform geochemical characteristic. Combining geochronological and geochemical analyses, we propose that the basites of the Sugetbrak Formation probably recorded a rifting event on the north‐western margin of the Tarim Craton during Early Cambrian.

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Section: Discussionsupporting

confidence: 60%

⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

Zhu

Jourdan

et al. 2018

Geological Journal

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“…The base of the Lower Cambrian is defined by an 8-10 m succession of interbedded black shales and organic-rich carbonate beds that correspond to the phosphorite unit described by Carroll et al (2001) and Yu et al (2003). This is overlain by a c. 100-m-thick, fine-grained dark grey dolomite that, together with the underlying shale unit, characterizes the Yurtusi Fm.…”

Section: The Early Palaeozoicmentioning

confidence: 93%

“…It is therefore possible that the unconformity separating the latest Neoproterozoic from the Lower Cambrian phosphorite beds could relate to the termination of active extension and the transition to thermally driven post-rift subsidence. Furthermore, reports that black, anoxic shales were deposited in gradually infilling and isolated basins elsewhere in the NW Tarim Basin have also been coupled to post-rift subsidence (Yu et al 2003). …”

Section: Stage 3: Post-rift Subsidencementioning

confidence: 99%

“…In this study, significant accumulations of a suitable source rock interval were not directly observed in the NW Tarim Basin. However, Yu et al (2003Yu et al ( , 2009) describe local accumulations of highly anoxic, organic-rich source rocks in the Lower Cambrian, deposited during the post-rift phase, elsewhere in the basin. It is likely that, should significant source rock accumulations exist, subsequent phases of basin subsidence and sedimentation would have subjected the source rock interval to sufficient burial depths for hydrocarbon maturation and expulsion.…”

Section: Hydrocarbon Prospectivitymentioning

confidence: 99%

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Late Neoproterozoic to Early Palaeozoic evolution and hydrocarbon prospectivity of the NW Tarim Basin, China

Turner

2012

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Recent contraction in the NW Tarim Basin, China, has exhumed a thick (2-3 km) sequence of Upper Neoproterozoic to Lower Palaeozoic sediments that provide a unique insight into the early evolution of the basin. The sedimentary sequence was examined in outcrop and consists of a lower, 500-m-thick fluvial-lacustrine clastic and volcanic succession, conformably overlain by a 2000-m-thick shallow marine carbonate succession which records a major rifting event that initiated in the Late Neoproterozoic. This rifting event probably corresponds to the breakup of East Gondwana and the separation of the Tarim Block from a conjugate margin equivalent in NW Australia. The generation and infilling of rift basins creates a number of potential hydrocarbon plays, although analysis of individual play elements indicates a relatively high risk, despite the prevalence of hydrocarbons derived from the same rift sequence elsewhere in the basin.

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“…The correlation between the Tarim and Yangtze Blocks regarding glaciation is discussed here. Identifying the interbedded black shales and organic-rich carbonate beds as correlative to the Precambrian-Cambrian boundary phosphorite unit found widely across China provides one important chronological constraint for the lower Yuertus and upper Chigebrak Formations (Carroll et al 2001;Yu et al 2003). Otherwise, the Neoproterozoic succession in this region lacks precise radiometric ages.…”

Section: Depositional Age and Glaciations Correlationmentioning

confidence: 99%

Age and nature of Cryogenian diamictites at Aksu, Northwest China: implications for Sturtian tectonics and climate

Ding

Lin

et al. 2015

International Geology Review

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Geochemistry of black shale at the bottom of the Lower Cambrian in Tarim Basin and its significance for lithosphere evolution

Cited by 19 publications

References 10 publications

⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

Late Neoproterozoic to Early Palaeozoic evolution and hydrocarbon prospectivity of the NW Tarim Basin, China

Age and nature of Cryogenian diamictites at Aksu, Northwest China: implications for Sturtian tectonics and climate

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Geochemistry of black shale at the bottom of the Lower Cambrian in Tarim Basin and its significance for lithosphere evolution

Cited by 19 publications

References 10 publications

40Ar/39Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

40Ar/39Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

Late Neoproterozoic to Early Palaeozoic evolution and hydrocarbon prospectivity of the NW Tarim Basin, China

Age and nature of Cryogenian diamictites at Aksu, Northwest China: implications for Sturtian tectonics and climate

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⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton

⁴⁰Ar/³⁹Ar ages and geological significance of Neoproterozoic–Cambrian mafic rocks in the Aksu–Wushi area, NW Tarim Craton