MEGASTAGES IN THE TECTONIC DEVELOPMENT OF ASIA
摘要
According to the main features in stratigraphical and development, as well aspalaeobiogeography and basement formation, six domains, three stable, (i) the NorthAsian Continental, (ii) the Mid-Continent Axial, (iii) the South Asian Continental, andthree mobile, (ix) the North Asian Intercontinental, (v) the South Asian Intercontinentaland (vi) the Circum-Pacific Continent Marginal, are recognized in Asia. By resorting tothe time of fundamental changes in the pattern of Asia, five megastages of tectonicdevelopment may be designated, which are denominated in terms of the notable orogenicmovements delimiting them. They are: (i) pre-Fupingian, ending with the Archaean, (ii)post-Fuping-pre-Luliangian, ending with the Early Proterozoic, (iii) post-Luliang-pre-Jinningian, ending in the middle of the Late Proterozoic, (iv) post-Jinning-pre-Indosinian, ending with the Middle Triassic, and (v) post-Indosinian. The Precambrian history of crustal development of Asia is that of crustal thicken-ing and accretion, which starts from the formation of cratonic nuclei, then of protoplat-forms and finally of platforms in the Late Proterozoic. From Sinian (800-600 my BP)to Early Triassic, the history is characterized both by crustal accretion through conso-lidation of marginal seas and island arcs, and by crustal fracturing leading to generationof new mobile belts. The Indosinian orogeny marks the beginning of large-scale displace-ment between different continents. Earth movements of different modes and categories probably owe their origin to dif-ferent depths below the earth's surface. Thus continental drift and sea floor spreadingseem to have resulted from gliding on surfaces in the upper part of the asthenosphere.Various kinds of tectonic systems may have affected only the upper half of the crust,while gravity folds and allied features are probably only concerned with the uppermost por-tion, say within a few kilometers, of the crust.