Plate Reconstruction Of The North And South China Blocks Under The Global Background

Plate reconstruction is the main way to understand the plate tectonic movement system, that is to reveal the kinematic features and the mechanism of the internal dynamic properties of plate tectonic system. The interpretation of the evolution cycler of the oceanic crust by the Wilson cycle has risen a high interest of study supercontinents. As significant components of Precambrian cratons, the North and South China blocks is remaining in unfairly mysterious in supercontinent reconstructions. A synthesis consider of geochemical, geophysical, geochronological, stratigrapgic, geobiological and paleomagnetic data has been taken in the thesis, and the tectonic-magma-metamorphism events of the Qinling-Dabie orogen is also reviewed and generate the map by using the reconstruction application GPlates. Few points are gained as following:(1) As for the supercontinent Rodinia, the paleomagnetic data shows that the North China Block (NCB) and the Laurentia may close to a same plate, indicating that the NCB probably as a part of Rodinia. Besides, this link between the NCB and the Laurentia stopped between 650-615 Ma and the NCB was close to the equator. It also implys that the NCB and the Laurentia should be separated by some plate, which could be the Siberia during 1800-1350 Ma. At the same time, the lately obtained two high quality paleomagnetic poles from the NCB (the～1770 Ma and the～1350 Ma, respectively) also suggest that the NCB might also close to the Siberia in Rodinia, and the connection can be tracked back to～ 1800 Ma and lasted after the break-up of Rodinia (-600 Ma). However, some younger paleomagnetic data from the Proterozoic rocks of the NCB shows that the NCB was required a 90° rotation movement during～1200-700 Ma. What is more, the lack of the Neoproterozoic strata of the NCB also suggests there was a certain distance from the NCB to the South China Block (SCB)-Australia region for the Neoproterozoic magma are widespread all over the SCB and the Australia. On the other hand, although the "Missing～Link" opinion that suggests the SCB was a bridge to link the eastern Australia and the western Laurentia has received a widely support, this theory requires the break-up of Rodinia to turn the inside out to release the SCB. Additionally, it causes a very complicated movement of the SCB to get to the place that it lately was in the Gondwana, which was at the northern margin of the Gondwana. Accorsding to the analysis of the detrital zircon ages and the paleomagnetic data, implying that the SCB may dock at the northern India-Australia margin since Rodinia and stayed still during the break-up of Rodinia to the formation of Gondwana. (2) As for the Gondwana superterrane, no strong evidences strongly suggest that the NCB has a direct touch with Gondwana, but the geobiographic data show that the NCB and SCB belonged to the Greater Australia Biogeology Province. Besides, available paleomagnetic poles also show that the NCB was located in the Southern Hemisphere around 15° during Cambro-Ordovinian and shared a similar latitude range with the SCB in the early Paleozoic. Meanwhile, multiple evidences suggest that the SCB on the northern margin of the India-Australia in Gondwana. A direct SCB-Australia alignment was existing from the early Cambrian to the early-middle Devonian. The paleopoles from the SCB and Australia overlap in some extent since Rodinia and maintained by the middle Devonian. Finally, (3) the North Qinling Terrane probably behaved as an independent continental arc during the Precambrian, and likely was involved into the Grenvillie Orogeny with the Cathaysia Blcok at～1.0 Ga, participating into the consequently combination process betweent he NCB and the SCB in the Phanerazoic.