Diverse subduction and exhumation of tectono-metamorphic slices in the Kalatashitage area, western Paleozoic Dunhuang Orogenic Belt, northwestern China

Zhang, Qian W.L.; Wang, Hao; Liu, Jiahui; Shi, Mengyan; Chen, Yi-Chao; Li, Zhen M.G.; Wu, Chun‐Ming

doi:10.1016/j.lithos.2020.105434

Cited by 15 publications

(29 citation statements)

References 110 publications

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“…5A-C, H). Similar decomposition textures in mafic granulites can be found elsewhere and are repeatedly demonstrated to be formed under severe decompression during tectonic exhumation (e.g., Wang et al, 2016Wang et al, , 2017aPetrakakis et al, 2018;Zhang et al, 2020). Other retrograde assemblages include finegrained ilmenite (Ilm3) ± plagioclase (Pl3) ± hornblende (Hbl3) ± titanite (Ttn3) lamellae exsolved from within the clinopyroxene (Cpx2) (Fig.…”

Section: Petrographysupporting

confidence: 72%

“…Although the UHP rocks were found within a limited granitic pluton, however, it is reasonable to infer that other UHP rocks, either more or less, are buried in the root of the Dunhuang orogenic belt. Furthermore, it is found both medium and high P/T facies series metamorphism occurred in this orogen in the Silurian to Devonian (Wang et al, 2017a(Wang et al, , b, 2018aZhang et al, 2020). The UHP garnet clinopyroxenite reported in this contribution further demonstrates that different metamorphic P/T facies series may prevail in a same orogenic belt, which is neglected to different extent in the past.…”

Section: Possible Fast Exhumation Of the Uhp Metamorphic Rocksmentioning

confidence: 51%

“…Until recently, clockwise metamorphic P-T paths of eclogite, mafic granulite, amphibolite and metapelite, typical metamorphic products of subduction background, were retrieved elsewhere in this region (Zhang et al, 2012;Zong et al, 2012;He et al, 2014;Peng et al, 2014;Zhao et al, 2016;Wang et al, 2016Wang et al, , 2017aWang et al, , b, 2018aZhang et al, 2020). The metamorphic event was dated to have occurred in the Silurian to Devonian era (Zong et al, 2012;He et al, 2014;Wang et al, 2016Wang et al, , 2017aWang et al, , b, 2018aZhang et al, 2020). These enabled people to believe that this area was a Paleozoic orogenic belt (Zhao et al, 2016;Wang et al, 2017a, b;2018a, b;Zhang et al, 2020), albeit the subduction https://doi.org/10.5194/se-2020-95 Preprint.…”

Section: Introductionmentioning

confidence: 99%

“…The metamorphic event was dated to have occurred in the Silurian to Devonian era (Zong et al, 2012;He et al, 2014;Wang et al, 2016Wang et al, , 2017aWang et al, , b, 2018aZhang et al, 2020). These enabled people to believe that this area was a Paleozoic orogenic belt (Zhao et al, 2016;Wang et al, 2017a, b;2018a, b;Zhang et al, 2020), albeit the subduction https://doi.org/10.5194/se-2020-95 Preprint. Discussion started: 29 June 2020 c Author(s) 2020.…”

Section: Introductionmentioning

confidence: 99%

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First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from P-T paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

Wang

Zhang

et al. 2020

Preprint

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Abstract. Ultra-high pressure (UHP) metamorphism is recorded by garnet clinopyroxenite enclaves enclosed in an undeformed, unmetamorphosed granitic pluton, northeastern Paleozoic Dunhuang orogenic belt, northwest China. Three to four stages of metamorphic mineral assemblages have been found in the garnet clinopyroxenite, and clockwise metamorphic pressure-temperature (P-T) paths were retrieved, indicative of metamorphism of a possible subduction environment. Peak metamorphic P-T conditions (790~920 °C/28~41 kbar) of garnet clinopyroxenite suggest that they experienced high pressure to UHP metamorphism, and the UHP metamorphism occurred in the coesite- or diamond-stability field. The UHP metamorphic event is further confirmed by the occurrence of high-Al titanite enclosed in the garnet, along with at least three groups of aligned rutile lamellae exsolved from within the garnet. SIMS U-Pb dating of metamorphic titanite indicates that the post peak, subsequent tectonic exhumation of the UHP rocks occurred in the Devonian (~ 389~370 Ma). These data suggest that part of the Paleozoic Dunhuang orogenic belt experienced UHP metamorphism, and diverse metamorphic facies series prevailed in this orogen in the Paleozoic. It can be further inferred that most of the UHP rocks of this orogen are now buried in the depth.

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Section: Petrographysupporting

confidence: 72%

Section: Possible Fast Exhumation Of the Uhp Metamorphic Rocksmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from P-T paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

Wang

Zhang

et al. 2020

Preprint

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“…The alternative reason is that these different granulite samples possibly experienced divergent depths or paths in the burial process and were amalgamated to the same crustal level in the later exhumation process, which is a common situation in Phanerozoic orogenic belts (e.g. Li, Gao, & Wang, 2016; Wang, et al., 2017b; Zhang et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

Metamorphic evolution and SIMS U–Pb geochronology of orthopyroxene‐bearing high‐Psemipelitic granulite in the Fuping area, middle Trans‐North China Orogen

Liu

Zhang

Wang

et al. 2020

Journal Metamorphic Geology

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The Fuping area lies in the middle part of the Trans‐North China Orogen, which is a critical region for understanding the metamorphic–tectonic evolution of this orogenic belt in the Precambrian. The newly discovered orthopyroxene‐bearing semipelitic granulite in this area is a coherent stratigraphic unit, among which three generations of metamorphic mineral assemblages (peak, post‐peak and cooling retrograde) have been identified based on petrographic observation and mineral chemical analysis. The peak metamorphic mineral assemblage mainly consists of porphyroblastic garnet plus matrix minerals including biotite, plagioclase, orthopyroxene, quartz as well as accessory minerals including pyrite, monazite, zircon and apatite. Geothermobarometry calculations and phase equilibria modelling confirm that the representative samples record different P–T conditions and metamorphic stages due to retrogressive metamorphism, with the highest P–T conditions reaching high‐P granulite facies. The retrieved clockwise metamorphic P–T paths pass from 12.5 to 13.5 kbar/855–880℃ (peak stage) through 8.5–11 kbar/850–886℃ (post‐peak stage) and to a speculative cooling phase (retrograde stage), reflecting near isothermal decompression (ITD) followed by near isobaric cooling (IBC). This P–T path is interpreted to reflect a subduction and/or collision event followed by a rapid exhumation. Secondary ion mass spectrometry (SIMS) U–Pb dating on metamorphic monazite and zircon yielded metamorphic ages ranging from 1,825 to 1,815 Ma, possibly constraining a retrograde metamorphic age. Therefore, the semipelitic granulite in the Fuping area records the subduction/collision event between the Eastern and Western Blocks of the North China Craton during the Late Palaeoproterozoic.

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Origins of the meta‐mafic rocks in the southern Dunhuang Block (NW China): Implication for tectonic framework of the southernmost Central Asian Orogenic Belt

Shi

Hou

et al. 2021

Geological Journal

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The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogenic collages in the world with prominent juvenile crust addition, where the southernmost margin of the CAOB located is one hot topic in the international studies. The Dunhuang Block located to the south of the Beishan Orogen is a key position for outlining the tectonic framework of the south margin of the CAOB. However, at present, the tectonic attribution of the Dunhuang Block is still controversial. In this paper, we focus on the origins and protoliths of the meta‐mafic rocks from the Hongliuxia complex in the southern Dunhuang Block for determining the tectonic attribution of the Dunhuang Block. In the field, the meta‐mafic rocks are mainly exposed as tectonic blocks within the metasedimentary rocks displaying the “block‐in‐matrix” fabrics or as tectonic slices juxtaposed by faults. Geochemically, the meta‐mafic rocks could be divided into three groups based on the rare earth elements (REE) and trace elements: the group 1 samples are depleted in the LREE relative to HREE and show flat HREE patterns, similar to the mid‐oceanic ridge basalt; the group 2 samples show flat REE patterns without obvious differentiation between the LREE and HREE, like the oceanic plateau basalt; the group 3 samples are enriched in LREE relative to LREE, and have negative Nb, Ta, and Ti anomalies, similar to the island arc basalt. Conclusively, the protoliths of the meta‐mafic rocks dominantly belong to the oceanic plate components. They were metamorphosed during Early Silurian to Middle Devonian in different depths of the subduction zone documented in previous studies. So, we suggest the Hongliuxia complex is an exhumed Palaeozoic subduction–accretion complex (SAC) formed during the oceanic plate subduction. This result confirms the Palaeozoic subduction event occurred in the Dunhuang region and indicates that the Dunhuang Block is a Palaeozoic Orogen rather than a part of Precambrian continent block. Considering the regional geology context, we speculate the Dunhuang Orogen belongs to the southernmost margin of the CAOB.

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Diverse subduction and exhumation of tectono-metamorphic slices in the Kalatashitage area, western Paleozoic Dunhuang Orogenic Belt, northwestern China

Cited by 15 publications

References 110 publications

First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from <i>P</i>-<i>T</i> paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from <i>P</i>-<i>T</i> paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

Metamorphic evolution and SIMS U–Pb geochronology of orthopyroxene‐bearing high‐Psemipelitic granulite in the Fuping area, middle Trans‐North China Orogen

Origins of the meta‐mafic rocks in the southern Dunhuang Block (NW China): Implication for tectonic framework of the southernmost Central Asian Orogenic Belt

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Diverse subduction and exhumation of tectono-metamorphic slices in the Kalatashitage area, western Paleozoic Dunhuang Orogenic Belt, northwestern China

Cited by 15 publications

References 110 publications

First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from &lt;i&gt;P&lt;/i&gt;-&lt;i&gt;T&lt;/i&gt; paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from &lt;i&gt;P&lt;/i&gt;-&lt;i&gt;T&lt;/i&gt; paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

Metamorphic evolution and SIMS U–Pb geochronology of orthopyroxene‐bearing high‐Psemipelitic granulite in the Fuping area, middle Trans‐North China Orogen

Origins of the meta‐mafic rocks in the southern Dunhuang Block (NW China): Implication for tectonic framework of the southernmost Central Asian Orogenic Belt

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First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from <i>P</i>-<i>T</i> paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite

First report of ultra-high pressure metamorphism in the Paleozoic Dunhuang orogenic belt (NW China): Constrains from <i>P</i>-<i>T</i> paths of garnet clinopyroxenite and SIMS U-Pb dating of titanite