RESEARCH ON THE FINE STRUCTURE OF CRUST-MANTLE IN TECTONOPHYSICS
Chen Shengzao Institute of Geophysics, Stute Seismological Bureau, Beijing
The fine structure of crust-mantle is closely relevant to some basic geoscience problems, such as tectonism, deformations, seismicity and its genesis, magmatism, metamorphism and metallization,change of the earth's temperature and its evolution and so on. The problems on the genesis of anomalous mantle, the thin-skinned and lithospheric plate tectonics and the isostatic adjustment and isostatic models are discussed based on the study of crustal fine-structure in the Jiangsu-Zhejiang- Anhui region combined with the deep-level geological data at home and abroad in this paper. The following knowledges are gained. 1.There are three kinds of possible geneses of anomalous mantle, i. e., A. the model of up-doming and heating of the low-velocity channel (LVC) accompanied by partial melting; B. the model of diapiring of mixed asthenospheric material and molten material of the LVC; C. the model of direct upwelling of astbenosphe- ric material penetrating through the lithosphere. 2.The thin-skinned plate, which is considered as the basic element of the lithospheric plate, not only exists in sia- lic crust but also is fit for the lower crust-top of upper mantle; and there are some crustal fine-structure features of detachments across southern Jiangsu-continen- tal shelf of the East China Sea. 3. During the isostatic adjustrnent the M_0 discon- tinuity, a top surface of the low-density layer in the uppermost mantle, could be taken as the isostatic compensation surface of Airy model. The isostatic models of the Jiangsu-Zhejiang-Anhui region are given in tbe paper.