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Geodynamic Development of the South China Block from Precambrian to Cretaceous: Constraints from Geology Geochemistry and Geochronology

Date

2018-11-05

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0000-0001-5231-6160

Type

Thesis

Degree Level

Masters

Abstract

The geo-tectonic evolution of the South China block is subject to debate. Most articles tend to subdivide the South China block into two sub-ordinate blocks (Yangtze and Cathaysia), with a central Sibao (Jiangnan) Orogen, although there are also suggestions for a separate eastern (Tolo) block. Debate primarily occurs around the timing of amalgamation of the Yangtze and Cathaysia blocks and the processes causing various episodes of magmatism. Some publications indicate that the South China block amalgamated between 800 and 900 Ma, but others propose amalgamation between 400 and 500 Ma. A recent paper suggests that the eastern portion of Cathaysia only collided with Cathaysia in the Jurassic. In this project, we bring together multiple data sets to develop a more constrained plate tectonic model for the South China block between ~1000 Ma and ~100 Ma. Compiled data include: zircon geochronology data, whole rock Lu-Hf isotope data, whole rock Sm-Nd and Rb-Sr isotopes data, rock major and trace element data. Geochronology data concentrate on U-Pb zircon and monazite data for the crystallisation ages of igneous rocks and near-peak metamorphism although lower-temperature closure ages have also been compiled where included in papers on crystallisation and metamorphism. Detrital zircon U-Pb data have also been compiled to aid in understanding changing sources of sediments through time to further constrain potential geodynamic processes. Lithochemistry data are used to infer geodynamic setting for igneous activity or for protolith formation. Together, these various data permit one to distinguish between upper and lower plate settings and to identify rifted environments. Precise location information is captured where available or approximated from published diagrams, correlated with available geological GIS maps. U-Pb and Sm-Nd isotope data for rocks formed between 900 and 800 Ma demonstrate primarily juvenile sources whereas the 400 to 500 Ma igneous activity reworked substantially older crust. Detrital zircon data show that the grains from South China block are primarily self-sourced. The combined data thus support models inferring collision of Cathaysia with Yangtze between 900 and 800 Ma and later SCB collide with potentially Australia at ~400 Ma.

Description

Keywords

Geochronology, Geochemistry

Citation

Degree

Master of Science (M.Sc.)

Department

Geological Sciences

Program

Geology

Citation

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DOI

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