Jin-Cheng Zhou

Bio: Jin-Cheng Zhou is an academic researcher from Nanjing University. The author has contributed to research in topics: Basalt & Mafic. The author has an hindex of 8, co-authored 9 publications receiving 1229 citations.

Geochemistry of Meso- and Neoproterozoic mafic-ultramafic rocks from northern Guangxi, China: Arc or plume magmatism?

Abstract: Meso- and Neoproterozoic mafic-ultramafic rocks from northern Guangxi show mainly calc-alkaline features. The mafic rocks have (Nb/La)pm1) = 0.13∼0.51, (Th/La)pm = 0.85∼3.3, Ti/Ti∗2) = 0.29∼0.79 and show negative Nb and Ti anomalies in primitive mantle normalized diagrams. The Mesoproterozoic mafic rocks have lower eNd(T) than those of Neoproterozoic, -1.99 ∼ -5.13 vs. -0.74 ∼ 2.4, respectively. They plot in the field of volcanic arc basalt in tectonic discrimination diagrams and display geochemical signatures of island arc volcanics. The mafic-ultramafic rocks are thought to be the products of magmatism of convergent plate boundary rather than derived from mantle plume. Therefore, they can not be regarded as an indicator of breakup of Rodinia supercontinent.

The Lhasa Terrane: Record of a microcontinent and its histories of drift and growth

Abstract: article i nfo The Lhasa Terrane in southern Tibet has long been accepted as the last geological block accreted to Eurasia before its collision with the northward drifting Indian continent in the Cenozoic, but its lithospheric architecture, drift and growth histories and the nature of its northern suture with Eurasia via the Qiangtang Terrane remain enigmatic. Using zircon in situ U-Pb and Lu-Hf isotopic and bulk-rock geochemical data of Mesozoic-Early Tertiary magmatic rocks sampled along four north-south traverses across the Lhasa Terrane, we show that the Lhasa Terrane has ancient basement rocks of Proterozoic and Archean ages (up to 2870 Ma) in its centre with younger and juvenile crust (Phanerozoic) accreted towards its both northern and southern edges. This finding proves that the central Lhasa subterrane was once a microcontinent. This continent has survived from its long journey across the Paleo-Tethyan Ocean basins and has grown at the edges through magmatism resulting from oceanic lithosphere subduction towards beneath it during its journey and subsequent collisions with the Qiangtang Terrane to the north and with the Indian continent to the south. Zircon Hf isotope data indicate significant mantle source contributions to the generation of these granitoid rocks (e.g., ~50-90%, 0-70%, and 30-100% to the Mesozoic magmatism in the southern, central, and northern Lhasa subterranes, respectively). We suggest that much of the Mesozoic magmatism in the Lhasa Terrane may be associated with the southward Bangong-Nujiang Tethyan seafloor subduction beneath the Lhasa Terrane, which likely began in the Middle Permian (or earlier) and ceased in the late Early Cretaceous, and that the significant changes of zircon eHf(t) at ~113 and ~52 Ma record tectonomagmatic activities as a result of slab break-off and related mantle melting events following the Qiangtang-Lhasa amalgamation and India-Lhasa amalgamation, respectively. These results manifest the efficacy of zircons as a chronometer (U-Pb dating) and a geochemical tracer (Hf isotopes) in understanding the origin and histories of lithospheric plates and in revealing the tectonic evolution of old orogenies in the context of plate tectonics.