Revisiting Neoproterozoic tectono-magmatic evolution of the northern
margin of the Yangtze Block, South China
Peng Wu
Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu, Sichuan 610059, China, College of Earth Science, Chengdu University of Technology, 610059, China
Corresponding Author:[email protected]
Author ProfileHao Song
Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu, Sichuan 610059, China, College of Earth Science, Chengdu University of Technology, 610059, China
Author ProfileZhengqi Xu
Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu, Sichuan 610059, China, College of Earth Science, Chengdu University of Technology, 610059, China
Author ProfileZeming Shi
Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu, Sichuan 610059, China, College of Earth Science, Chengdu University of Technology, 610059, China
Author ProfileAbstract
The Neoproterozoic tectonics of South China is crucial for understanding
its evolution history throughout the assembly and disintegration of
Rodinia. Herein, we employ integrally tectono-magmatic records over the
period of ~1.0-0.6 Ga from the northern Yangtze block,
combining with available geochemical and geological data, to investigate
the secular tectonic evolution of the craton. Early Neoproterozoic
intra-oceanic subduction may have initiated at ~1.0-0.9
Ga after a long-period of late Mesoproterozoic passive margin. A
flare-up of magmatism at ~900 Ma attributed to
continental arc magmatism that led to increased crustal reworking during
episodes of arc compression and lithospheric thickening, and
subsequently enhanced juvenile mantle input during the transition to
extensional back-arc rift modes. The isotope–time pattern displays
cyclic trends shifting towards less radiogenic values and then
progression to more radiogenic, near-depleted mantle isotope
compositions, indicating alternation regimes of contractional and
extensional tectonics due to repeatedly slab advancing and rollback. The
occurrence of volumetrically-large radiogenic isotope-depleted
calc-alkaline rocks associations, low-δ18O and bimodal rocks along the
Yangtze-block continental margin likely indicates rapid reworking of
juvenile crust within a composite tectonic setting involving both arcs
and rifts, which may maintain until the end of calc-alkaline arc
magmatism at ~730-720 Ma and ultimately evolved into an
anorogenic rifted passive margin setting, as revealed by the deposition
of massive ~720-620 Ma syn-rift Yaolinghe-group
volcanic-sedimentary sequence and intraplate-like magmatism.
Collectively, prolonged (~1.0-0.7 Ga)
suprasubduction-related magmatism traces accretion to the Yangtze-block
margin, and thus likely indicates a paleogeographically peripheral
position of South China in Rodinia.