Oceanic island basalts in ophiolitic mélanges of theCentralChinaOrogen: An overview

Abstract

We present an overview of the internal structure of the 10 ophiolitic mélanges in the Central China Orogen (CCO) with a focus on the geochemical character and tectonic evolution of the ophiolitic mélange‐related ocean island basalt (OIB) and mafic rock assemblages. The ophiolitic mélanges in CCO are generally complicated and usually consist of metamorphic peridotites (serpentinite), cumulates, gabbros, basaltic lavas (pillows), and abyssal radiolarian cherts. The ages of ophiolitic mélanges range from Mesoproterozoic to Carboniferous. The OIB‐type basalts and mafic rocks in CCO occur as tectonic blocks within the mélanges that are composed of limestones, radiolarian cherts, and turbidites, possessing formation characteristics of seamounts (oceanic islands/plateau). The mafic rocks in ophiolitic mélanges of CCO display uniform chondrite‐normalized rare earth element (REE) patterns with light REE enrichment and heavy REE depletion, no obvious Eu anomalies or negative Nb, Ta, and Ti anomalies, and primitive mantle‐normalized trace element patterns with significant large‐ion lithophile element enrichment, similar to those of modern OIB and the Hawaiian alkaline basalts. The OIB‐type basalts and mafic rocks are considered as accreted seamount fragments in an accretionary complex of CCO and may represent plume‐related magmatism within the Proto‐Tethys Ocean and Paleo‐Tethys Ocean. Our study provides further insights into the processes of multiple subduction and long‐lasting accretionary histories with seamounts in the CCO.

Petrology and Tectonic Geophysics of Massive and Foliated Eclogites in the North Qilian Orogenic Belt: Changes in Mineral Composition, Oxygen Fugacity, and Fabric during Exhumation

“…Many prob-lems are difficult to solve by traditional methods. Since in situ Lu-Hf isotope analysis of zircon is often used in current analysis, the following mainly introduces the in situ Lu-Hf isotope analysis of zircon [29][30][31][32][33].…”

Central China Orogen along the Silk Road (Part I): Tectono‐thermal evolution and its links

“…The discovery of Mesoproterozoic magmatic zircons is used by Cao et al () to demonstrate the Precambrian tectonic affinity of the North Qinling Microcontinent. Yang, Li, Tong, Wang, and Wu () provide an overview of ophiolitic mélanges in the Central China Orogen. In the paper by Li, Liu, Niu, and Hu (), Triassic Tethyan‐type sedimentation in the Qinling Orogeny is assessed.…”

Geochronology, geochemistry, and Hf isotopes of mafic rocks from Dalabute ophiolitic mélange in West Junggar, Xinjiang (NW China): Implications for the magmatic source and tectonic setting

“…It is an important part of the Central Asian‐Xingmeng Macroscopic Tectonic‐metallogenic domain (Cai et al, ; Cai, Long, Chen, Sun, & Xiao, ; Zhang & Zhu, ; Zhu, Zhang, Gu, Guo, & Zhou, ) and is also one of the research hot spots of the CAOB. Many significant achievements and remarkable progresses have been made in the geologic structure, tectonic evolution, and metallogenesis of metallic deposits in this area (Kovalenko et al, ; Geng et al, ; Tang et al, ; Liu et al, ; Chen et al, ; Liu, Li et al, ; Yang, Li, Tong, Wang, & Wu, ; Yin et al, ; Furnes & Safonova, ; Zhang, Xiao et al, ; Zheng, Zhao, & Yang, ). Since the Palaeozoic, Siberian, Kazakhstan, and Tarim plates have been assembled together in the north‐west corner of China and the vast areas that extend outward, which include the West Junggar.…”