Some Aspects of the Hainan and Guangdong Terranes
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Abstract
The Carboniferous Guangdong continent and Hainan Island are believed to be two distinct composite terranes based on the following main features.
(1)They have significantly different sedimentary formations. During the Permian Period. the Guangdong continent was an epeiric sea where the sediments dominated by the shallow-water carbonate rocks were deposited. whereas the Hainan Island was then a marginal sea where the deepwater sediments dominated by mudstones and siliceous mudstones were deposited.
(2)There was no transitional facies between the Guangdong continent and Hainan Island.
(3)The Hainan Island was isolated by the rifts all around: the Qiongzhou Channel rift to the north; the Yingge Sea rift to the west(The rift stretched northwestwards to the Red River rift in Viet Nam.), and the Southeast Qiongzhou rift to the southeast.
(4)The palaeotectonics of the Carboniferous sediments on the Guangdong continent tend to be controlled by a series of the NE-trending rifts, whereas those on the Hainan Island by the EWtrending rifts.
(5)The faunal provinces vary greatly. The fossils are very rich in vaiious horizons of the Guangdong continent, but very rare in those of the Hainan Island. There exist, on the Guangdong continent, blue-green algae and green algae which are absent on the Hainan Island. On the other hand, there occur, on the Hainan Island. the fossils Fusella Xeospirifer as well as the Cambrian Xystridura which are also absent on the Guangdong continent.
(6)After the Carboniferous Period. the Guangdong continent was compressed as a result of the NE-trending collision between the Pacific and Eurasian Plates resulting in intense magmatism and contact metamorphism. whilst the Hainan Island was compressed due to the collision of the NS-trending terranes leading to the regional metamorphism and strong silicification and schistositization.
(7)The differences between the two terranes may also be indicated by the pre-Carboniferous sedimentary records.
(8)It can be seen. from the palaeomagnetic data. that the Hainan Island once drifted from the south to the north and collided with the Guangdong continent.
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