Linking the Alxa Terrane to the eastern Gondwana during the Early Paleozoic: Constraints from detrital zircon U–Pb ages and Cambrian sedimentary records

Zhang, Jin; Zhang, Yiping; Xiao, Wenxia; Wang, Yannan; Zhang, Beihang

doi:10.1016/j.gr.2014.09.012

Cited by 63 publications

(17 citation statements)

References 82 publications

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“…The Precambrian rocks in the ATB have long been considered as Neoarchean to Early Paleoproterozoic in age and represent the western extension of the NCC, either a part of the Yinshan Block or the Khondalite Belt (Geng et al, ; J. X. Zhang et al, ; Zhao & Cawood, ). However, the discovery of Neoproterozoic magmatism in the ATB and comparable detrital zircon age spectra to the South China Craton spurred some authors to propose that the Precambrian basement of the ATB was independent from the NCC (e.g., Dan, Li, Wang, Wang, et al, ; J. Zhang, Zhang, et al, ). Despite of these debates, the basement rocks are regarded to have been extensively overprinted by Permian tectonothermal events related to the orogenic processes of the CAOB as revealed by muscovite 40 Ar‐ 39 Ar and zircon U‐Pb dating on metamorphic and deformed rocks (Geng & Zhou, ).…”

Section: Regional Tectonicsmentioning

confidence: 99%

Final Subduction Processes of the Paleo‐Asian Ocean in the Alxa Tectonic Belt (NW China): Constraints From Field and Chronological Data of Permian Arc‐Related Volcano‐Sedimentary Rocks

et al. 2018

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The timing of final subduction and closure of the Paleo-Asian Ocean (PAO) is controversial.Located in a key position within the southern Central Asian Orogenic Belt, the Alxa Tectonic Belt (ATB) provides a crucial window to evaluate the final subduction processes of the PAO. This study presents field and geochronological data for Permian volcano-sedimentary rocks from the southwestern ATB. Field observations revealed a syntectonic unconformity between the Middle and Upper Permian strata. Detrital zircon U-Pb analyses show a major peak at~273 Ma and a subordinate peak at~440 Ma for the Middle Permian sample. The Upper Permian samples show consistently unimodal age spectra with single peaks at 261 and~263 Ma, respectively. The Permian zircons from the analyzed samples yield predominately positive ε Hf (t) values, indicating major juvenile magmatic processes mixed with limited recycled Precambrian basement. The diagnostic zircon U-Pb-Hf isotopic characteristics and ubiquitous intermediate and felsic volcanic detritus in these rocks indicate rapid sediments accumulation sourced from a proximal magmatic terrane in a suprasubduction zone environment. The Paleozoic zircon U-Pb age peaks from this study are comparable to those for the Permian arc-related sediments along the Solonker Suture Zone, thus linking the Alxa active margin with the northern margin of the North China Craton during Middle-Late Permian times. Our study thus provides key constraints for the final subduction processes of the PAO, documented within the ATB, before the terminal amalgamation of the southern Central Asian Orogenic Belt.

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Section: Regional Tectonicsmentioning

confidence: 99%

Final Subduction Processes of the Paleo‐Asian Ocean in the Alxa Tectonic Belt (NW China): Constraints From Field and Chronological Data of Permian Arc‐Related Volcano‐Sedimentary Rocks

et al. 2018

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“…1). The Alashan (also called Alxa) Terrane has been treated as a doubtful part of the SKC in most Ordovician tectonic reconstructions, as its palaeogeographic position during the Early Palaeozoic is still hotly debated (Zhang et al, 2014). Based on evidence from Carboniferous and Permian palaeomagnetic results, Yuan and Yang (2014) indicated that it did not amalgamate with the SKC until late Permian time, but Wu and Min (2015) argued that it merged with the SKC in the Dapingian (Middle Ordovician).…”

Section: Geological Settingmentioning

confidence: 99%

Huaiyuan Epeirogeny—Shaping Ordovician stratigraphy and sedimentation on the North China Platform

Zhen

Zhang

Wang

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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Ordovician conodont studies have revealed a depositional hiatus extending from the late Floian to early Darriwilian on the North China Platform. Recognition of this widespread gap entails revision of the original concept of the Huaiyuan Epeirogeny, with definition of two distinct regional tectonic events: Event 1, which initiated this hiatus, and a subsequent Event 2 that was responsible for terminating Early Palaeozoic sedimentation in the region from the late Katian. The timing of these two events partly coincides with widely recognized eustatic sea-level falls, and separates Ordovician sedimentation into two episodes that can be broadly correlated with eustatic sea-level rises. In combination with these sea-level changes, the Huaiyuan Epeirogeny played a decisive role in shaping and controlling Ordovician sedimentation and sequence stratigraphic architecture on the North China Platform. Lower Ordovician carbonates were deposited during an apparent regression (decreasing accommodation space), resulting from rapid sediment accumulation exceeding the overall rate of basement subsidence and eustatic sea-level rise. Sedimentation ceased in the middle

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“…Yuan and Yang () reported the detrital zircon ages from the Shixiagou Formation sandstone of the middle Devonian and the Zhongning Formation sandstone of the upper Devonian in the eastern AB and constructed the relative probability diagram shown in Figure b, where there are two major age peaks at ~474 and ~999 Ma, and one moderate age peak at ~2,491 Ma. Zhang et al () reported the detrital zircon ages from the Xiangshan group sandstone of the middle‐upper Cambrian in the south‐eastern AB and constructed the relative probability diagram shown in Figure c, where there is one major age peak at ~964 Ma, and two moderate age peaks at ~2,517 and ~551 Ma. Darby and Gehrels () reported the detrital zircon ages from the sandstone of strata from the Proterozoic to Ordovician in the western Ordos Block and constructed the relative probability diagram shown in Figure d, where there are two major age peaks at ~1,999 and ~2,665 Ma.…”

Section: Discussionmentioning

confidence: 99%

“…Detrital zircon relative probability diagram of (a) the south‐western Alxa Block (Zhang, Zhang, Zhang, et al, ; Zhang, Zhang, & Zhao, ); (b) the eastern Alxa Block (Yuan & Yang, ); (c) the south‐eastern Alxa Block (Zhang, Zhang, Xiao, Wang, & Zhang, ); (d) the western Ordos Block (Darby & Gehrels, ); (e) the northern Yangtze Block (Wang, Griffin, Yu, & O'Reilly, ); and (f) the North Qilian Orogen (Xu et al, ) [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Discussionmentioning

confidence: 99%

“…In fact, when and how did the AB deviated from the NCC (Ordos Block) still remains unclear; the absence of basic rocks or bimodal volcanic rocks found in the eastern AB makes the evidence insufficient; we can only obtain the information that the AB is independent from the NCC during the Neoproterozoic because the ~900 Ma age peak of detrital zircons are absence in the NCC. However, many researchers consider that the AB was amalgamated onto the NCC again during the Paleozoic; they put forward multiple amalgamate periods as in the Ordovician, Devonian, or Carboniferous (Dan et al, ; Liu, Zhao, Liu, & Shi, ; Yuan & Yang, ; Zhang et al, ; Zhang, Zhang, Zhang, et al, ; Zhang, Zhang, & Zhao, ), but the age of the deviation mentioned above is indistinct. In this study, we consider that the AB was deviated from the NCC after ~2.0 Ga; because they have similar detrital zircon age peak at this time, they were likely to experienced common geological events at this time as an amalgamated plate; however, our detrital zircons indicate that the AB was in an extension‐rift environment during 900–800 Ma inside the RS, separated from the NCC.…”

Section: Discussionmentioning

confidence: 99%

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Tectonic affinity and evolution of the Alxa Block during the Neoproterozoic: Constraints from zircon U‐Pb dating, trace elements, and Hf isotopic composition

et al. 2018

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The Jinchuan deposit, which is located in the Longshoushan uplift (LU) on the southwest margin of the Alxa Block (AB), is the third largest Ni‐Cu deposit in the world. There are igneous rocks in the LU that widely developed in ~830 Ma, which include ore‐bearing ultramafic rock and ore‐poor mafic‐ultramafic rocks. These rocks were produced in an intracontinental extension‐rift environment, which is likely related to the Rodinia supercontinent (RS) breakup. However, contemporary magmatic rocks are absent in the AB, except the ~830 Ma igneous rocks in the LU. In this study, we present two types of metamorphic mafic‐ultramafic rocks at the border of Jinchuan II and IV mineral areas, which is inside the F17 fault zone. One type is a red‐coloured altered rock formed by ultramafic rock oxidation; there are a small number of zircons with multiple ages in the rock, which are considered to be inherited and metamorphic (hydrothermal) zircons. The other type is a chlorite tremolite schist formed by the metamorphism of fault clastics; there are a large number of zircons developed in this rock, which are mostly magmatic zircons with ages between 900 and 800 Ma and a few hydrothermal zircons. Analysis of the trace elements, the 900–800 Ma zircons, have high (Sm/La)N, low Ce/Ce*, and high Th/U values, which fit the characteristics of typical magmatic zircons. There are also high Y, U, HREE, Nb, and Ta values, which indicates that the host rocks were mostly larvikite and dolerite, and high Y, Ce, Yb, Th, Gd, and Er values indicate a within‐plate basaltic origin. All these 900–800 Ma zircons have a εHf (t) in the range of −2 to −7, which is similar to the Jinchuan ore‐bearing ultramafic rock with a partial melting origin of enriched mantle. The absence of detrital zircon age peaks in the Neoproterozoic indicates that the AB has been separated from the North China Craton since the Neoproterozoic to Paleozoic. The detrital zircons in the Yangtze Block (YB) strata with Neoproterozoic ages are slightly younger than those in the AB, with more depleted εHf (t) values, which is similar to the zircons from the Jiangnan Orogen igneous rocks. All this evidence indicates that the AB may have experienced at least 100 Myr of intracontinental extension‐rift environment from 900 to 800 Ma during the Neoproterozoic and participated in the breakup of the RS. However, the location of the AB during the Rodinia may not have been beside the YB.

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Linking the Alxa Terrane to the eastern Gondwana during the Early Paleozoic: Constraints from detrital zircon U–Pb ages and Cambrian sedimentary records

Cited by 63 publications

References 82 publications

Final Subduction Processes of the Paleo‐Asian Ocean in the Alxa Tectonic Belt (NW China): Constraints From Field and Chronological Data of Permian Arc‐Related Volcano‐Sedimentary Rocks

Final Subduction Processes of the Paleo‐Asian Ocean in the Alxa Tectonic Belt (NW China): Constraints From Field and Chronological Data of Permian Arc‐Related Volcano‐Sedimentary Rocks

Huaiyuan Epeirogeny—Shaping Ordovician stratigraphy and sedimentation on the North China Platform

Tectonic affinity and evolution of the Alxa Block during the Neoproterozoic: Constraints from zircon U‐Pb dating, trace elements, and Hf isotopic composition

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