Ca. 830 Ma back-arc type volcanic rocks in the eastern part of the Jiangnan orogen: Implications for the Neoproterozoic tectonic evolution of South China Block
“…The intervening Jiangnan orogen considered as a collisional belt 14–17 (Fig. 1) between the two, with the proposed timing of collision varying from late Mesoproterozoic 14 to middle Neoproterozoic 15–17 .Figure 1Simplified geological map of eastern South China (modified from Zhao and Cawood 52 ), showing the location of the honblendites.
…”
Section: Geological Setting and Sample Descriptionmentioning
Metamorphic zircon from a hornblendite in the South China Block (SCB) yield U-Pb age of 533 ± 7 Ma and Hf model ages from 900 to 1200 Ma. Geochemical and isotopic characteristics indicate that primary magma of the hornblendites was probably derived from an enriched asthenospheric mantle source. This Late Neoproterozoic–Cambrian (Pan-African) metamorphic event provides the first direct evidence that the SCB was an integral part of the Gondwana assembly. Combined with available geological data which show that the SCB has great affinity with India or Australia, the Pan-African metamorphic event most likely belongs to the eastern Kuunga orogeny. We propose that the SCB was located at the nexus between India, Antarctica and Australia along the northern margin of East Gondwana, with the Cathaysia Block connecting western Australia whereas the Yangtze Block facing northern India at ca. 533 Ma.
“…The intervening Jiangnan orogen considered as a collisional belt 14–17 (Fig. 1) between the two, with the proposed timing of collision varying from late Mesoproterozoic 14 to middle Neoproterozoic 15–17 .Figure 1Simplified geological map of eastern South China (modified from Zhao and Cawood 52 ), showing the location of the honblendites.
…”
Section: Geological Setting and Sample Descriptionmentioning
Metamorphic zircon from a hornblendite in the South China Block (SCB) yield U-Pb age of 533 ± 7 Ma and Hf model ages from 900 to 1200 Ma. Geochemical and isotopic characteristics indicate that primary magma of the hornblendites was probably derived from an enriched asthenospheric mantle source. This Late Neoproterozoic–Cambrian (Pan-African) metamorphic event provides the first direct evidence that the SCB was an integral part of the Gondwana assembly. Combined with available geological data which show that the SCB has great affinity with India or Australia, the Pan-African metamorphic event most likely belongs to the eastern Kuunga orogeny. We propose that the SCB was located at the nexus between India, Antarctica and Australia along the northern margin of East Gondwana, with the Cathaysia Block connecting western Australia whereas the Yangtze Block facing northern India at ca. 533 Ma.
“…However, the current understanding of the “Cathaysian ancient land” concept is now considerably modified from what was originally proposed (Lu, ). An increasing number of researchers now consider that metamorphic basement composed of Paleoproterozoic and Mesoproterozoic crust exists in south China, termed the “Cathaysian Block” or “Cathaysian Land,” which experienced collision–cracking process with the Yangtze Block (Chen & Rong, ; Li, Zhang, & Powell, ; Li, Li, Zhou, & Kinny, ; Li, Li, Li, Lo, & Wang, ; Li, Li, & Li, ; Li et al, , , ; Li, Lin, Xing, Jiang, & Xia, ; Wang, ; Wang & Shen, ; Wang et al, , ; Zhou & Zhu, ). The characteristics and tectonic evolution of the “Cathaysian Block” are important in understanding the tectonic framework and evolution of South China as a whole.…”
Section: Introductionmentioning
confidence: 99%
“…Paleoproterozoic and Mesoproterozoic crust exists in south China, termed the "Cathaysian Block" or "Cathaysian Land," which experienced collision-cracking process with the Yangtze Block (Chen & Rong, 1999;Li, Zhang, & Powell, 1996;Li, Li, Zhou, & Kinny, 2002;Li, Li, Li, Lo, & Wang, 2009;Li, Li, & Li, 2014;Li et al, 2013aLi et al, , 2013bLi et al, , 2016Li, Lin, Xing, Jiang, & Xia, 2018;Wang, 2000;Wang & Shen, 2003;Wang et al, 2006Wang et al, , 2007Zhou & Zhu, 1993). The characteristics and tectonic evolution of the "Cathaysian Block" are important in understanding the tectonic framework and evolution of South China as a whole.…”
Numerous volcanic–sedimentary rocks of the Wanquan and Gaiyang groups are found throughout the Nanping–Ninghua tectonic belt, South China. However, detailed studies on the tectonic evolution of the Nanping–Ninghua tectonic belt have been limited by the lack of systematic previous research linking these volcanic–sedimentary rocks. This study presents a systematic petrological, geochronological, and geochemical study of meta‐volcanic rocks from the Louqian Formation in Mingxi County, China. Zircons from these rocks were analysed by laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) and yielded a U–Pb weighted mean age of 734.7 ± 3.3 Ma. The SiO2 contents of the meta‐volcanic rocks range from 59.91 to 73.47 wt.%, and they have high Al2O3 and Na2O + K2O contents (13.17–18.80 and 6.73–11.19 wt.%, respectively), and low CaO, MgO, and FeOT contents. All samples are enriched in large‐ion lithophile elements (LILE; e.g., Ba, Rb, and K) and depleted in high‐field‐strength elements (HFSE; e.g., Nb, Ta, Ti, and P). Marked negative Eu anomalies are similar to those in arc igneous rocks. Based on regional geological data and previous studies, we propose that the Nanping–Ninghua tectonic belt formed in an active continental margin environment from 825 to 696 Ma. Island arc magmatism was caused by the oceanic crust subduction, which contributed to the formation of an intermediate–silicic volcanic belt along the Nanping–Ninghua continental margin that was active until 696 Ma. The North and South Wuyi blocks did not assembly to form a unified Wuyi Block before 696 Ma, and there is no unified pre‐Nanhua crystalline basement present in the Cathaysia Block.
“…Previous studies have suggested that the Yangtze and Cathaysia blocks collided along the southern Anhui–eastern Xuefeng margin–Miaoling line in the Jinning Period (850–820 Ma), forming a unified ancient South China continental plate (Li et al, , , ; Li, Lin, Xing, Jiang, & Xia, ; Shu, Faure, Yu, & Jahn, ; Wang & Li, ; Zhang et al, ). Li, Wang, Li, and Li () suggested that the lithosphere in South China thinned from ca .…”
The nature of the Precambrian basement in the Cathaysia Block of South China is controversial, which inhibits our understanding of the pre‐Devonian tectonic evolution of the region. In this study, a suite of amphibolites and marbles in northern Fujian area located in the north of the Cathaysia Block were subjected to LA–ICP–MS U–Pb zircon geochronological and geochemical analyses. Results show that the protolith of the amphibolite formed after ca. 459 Ma, and its metamorphism happened at ca. 429 Ma. The protolith of the marble was deposited after ca. 518 Ma, and its metamorphic age is ca. 437 Ma. The amphibolites are divided into two groups based on geochemical data. Group 1 has an OIB‐like feature that might have formed in an environment characterized by oceanic islands and seamounts. Magmas associated with Group 1 were derived from an enriched mantle source with OIB characteristics. The protolith of Group 2 shows IAB feature that formed in an island arc environment. Marbles are interpreted to represent metamorphosed marine carbonate rocks. Integration of geochronological and geochemical study indicates that the marble and amphibolite should be an early Palaeozoic oceanic island–seamount association. It suggests the Cathaysia Block underwent oceanic subduction during collisional orogenesis in the early Palaeozoic. This subduction is thought to have initiated prior to ca. 437 Ma. The U–Pb zircon ages of younger intrusive granites indicate that final amalgamation occurred before ca. 392 Ma. During this process, east and west Wuyi were amalgamated to form the unified Cathaysia Block. Thus, it suggests that there was no unified pre‐Devonian basement in the Cathaysia Block. The pre‐Devonian tectonic setting of the Cathaysia Block was an accretionary orogeny.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
