Research Field : Precambrian Geology and Supercontinent Evolution
The reconstruction of supercontinent, especially Rodina supercontinent, has received many attentions in last decades. The assembly and breakup of Rodinia are generally evidenced by many aspects, such as igneous and sedimentary rocks.
(1) Low-δ18O magma has profound implications on geological and climate evolution. We firstly report Neoproterozoic moderately 18O depleted zircons from the central part of the Cathaysia Block in South China. The similarity in low-δ18O magmatism between northwest India, Madagascar, and South China suggests close connections in the Rodinia supercontinent during the middle Neoproterozoic.
(2) Synthetic studies of the petrology, mineralogy, geochemistry, geochronology and isotopic geology have been carried on the Precambrian sedimentary sequences and igneous rocks from eastern Jiangnan Orogen. The presence of a back-arc basin system at ca. 860-820 Ma within the south-eastern margin of the Yangtze block also indicates that Rodinia assembly was not completed until ca. 820 Ma, with the South China block possibly acting as a connection between a Neoproterozoic Andean-type active continental margin and Grenvillian belts on the paleo–western margin of the Rodinia supercontinent.
(3) Besides, zircons from conglomerates can provide valuable information for crustal evolution. Based on comparisons of detrital zircon U–Pb age spectrums and Hf isotopic characters with worldwide continents, we propose that the early Neoproterozoic sediments at the southeastern margin of the Yangtze Block have close affinities with those from the India and East Antarctica, which matches a northwestern margin position for the SCB in the configuration of supercontinent Rodinia.
Precambrian geology in South China has also been hot-debated in recent years. We, our group, have gained some achievements in the following:
(1) We have proposed the Yangtze Block was not unified and witnessed heterogenous crustal evolution before Neoproterozoic, based on petrogenesis, geochemical modelling and data compilation. We also highlight the crucial role of Neoproterozoic intra-arc thrust belt on western Yangtze Block in driving endogenic recycling and contributing to magma diversity during continental arc evolution.
(2) High-Mg tonalites in the southern part of the ca. 830 Ma Dongma Pluton, northern Guangxi Province of South China, indicates the existence of Neoproterozoic subduction-related metasomatism in the western part of the Jiangnan Orogen. Furthermore, two episodes of Neoproterozoic mafic magmatism in the western segment of the Jiangnan Orogen shed light on the magma source transition from lithospheric mantle to depleted asthenospheric mantle.
(3) The Mesozoic granites in the middle Nanling area are characterized with more depleted zircon Hf and whole rock Nd isotopic compositions than granitoids in the western and eastern Nanling area, South China. We speculate the middle Nanling area was a sutural zone of Yangtze and Cathaysia block during the Neoproterozoic time, with more Neoproterozoic juvenile crustal materials (e.g., arc-magmatic rocks).
(4) Ophiolites can provide crucial constraints on the history of continental convergence. We focused on the South Anhui ophiolite and the Northeast Jiangxi ophiolite from eastern segment of the Jiangnan Orogen within the South China Block. The formations of these ophiolites record orogenic processes from the subduction of oceanic crust (early stage) to back-arc extension (late stage) and finally the closure of back-arc basins in South China from Mesoproterozoic to Neoproterozoic.
(5) A study on tectonic evolution and source analysis of Precambrian sedimentary strata in the northern margin of Yangtze block is important to decipher the history of Yangtze Block, and it revealed the early accretion in the periphery of continent.
(6) Moreover, owing to the improvement of the experimental petrology and phase equilibria modeling methods in recent decades, we used these powerful tools on Precambrian rock to explore the evidence of buried geological events.
