According to the sedimentation

magmatism

tectonics and isotopic data available from pre-Sinian basement rocks exposed along the margin of the upper Yangzi platform

it is suggested in view of stratigraphieal division that.1) the pre-Sibao (1700—1900 m.y.) magnisium-and iron-rich sediments

represented by Kongling group

are distributed along Sichuan-Jianghan region and controlled by the island chain composed of basic and ultrabasic rocks

they were subjected to regional metamorphism

migmatization and granization and finally turned to continental crust through consolidation;2) during Sibao period

the Sichaun-Jianghan continental crust largely emerged from water

with a miogeosyncline and a eugeosyncline lying parallel to north side which are similar to Atlantic type margin

while island-are type geosynclne

similar to Pacific type

along its south side.The Sibao movement (1400 m.y.) strongly influenced the south part and turned it into consolidated basement of continental crust;3) during Jinning period

the Jiangnan islan

dare continued its activities.At the same time

the back-are region

including north Guangxi and west Hunan

as well as Jianghan and east Sichuan

was evoluted into a miogeosyncline developed on a sialic crust.Carbonates and clastics

intercalated with intermediate-acidic volcanic rocks

formed along Kangdian Axis region with intermediate-acidic magnatic complexes placed in Kangdian Axis and Mr.Longmen area

implying an intensely active continental margin.The sedimentation in the ancient Qinlin Sea was continued from the preceeding eugeosyncline

but due to the compressive forces of Jinling movement (800 m.y.)

exerted toward both the north-east and north-west

the entire basement of the upper Yangzi platform drifted northward

it was then finally closed and welded into Huabei platform.Thus the upper Yangzi platform completely cratonized and converted into continental crust;4) during Chengjiang period

a large part of the upper Yangzi platform recieved sedimentation

while the Kangdian Axis and Mr.Longmen mountain-building arc still continued its action

leading to further basement consolidation of the present area.Based on the evolution characteristics

the degree and style of consolidation

the texture of the basement

the platform discussed can be divided into.a) Sichuan-Jianghan region which accordingly subdivided into strongly consolidated Sichuan basin(At)

with single tectostratigraphic unit

and eastern Sichuan and Jianghan region (A

2

)

with binary tectostratigraphic units

the upper one being slightly cratonized and the lower one being strongly cratonized;b) north Guangxi

west Hunan and east Yunnan region with also binary tectostratigraphic units

the upper one being slightly cratonized and the lower one moderately cratonized: c) the Kangdian Axis region with triple tectostratigraphic units with distinct lateral heterogeneity;and d) WudangBikou region with single tectostratigraphic unit.