PRELIMINARY NOTES ON THE STRATIGRAPHY AND GEOLOGICAL HISTORY OF ASIA
Compilation Group of the Geological Map of Asia
This paper is a brief summary of the stratigraphy of Asia and is a part of the outcome of the compilation work of the one to five million scale geological map of Asia. The principal points are as follows: 1. From a temporal point of view, the geological history of Asia may be subdivided into four megastages, which are designated in terms of the major tectonic episodes. They are: 1) the Pre-Luliangian, prior to 1600m.y., including the Archaean and the early Proterozoic. 2) the Laliangian-Chinningian, 1600—800 m.y., including the late Proterozoic prior to the Sinian period proper. 3) the ChinningianIndosinian, 800—200m.y., from the Sinian to the Middle Triassic, and 4) the post-Indosinian, from late Triassic to the present. 2. In accordance with the character of the basement and the regional variation of sedimentation types, six major stratigraphic domains may be distinguished. Three continental domains, the South Asian, the Mid-continent Axial and the North Asian, are formed mainly of Precambrian massifs. The North Asian Intercontinental Domain is a tectonically active belt characterized by Paleozoic folding and magmatic activities, while the South Asian and the Circum-Pacific conform in the main with the labile and active Mesozoic and Cenozoic belts. The Circum-Pacific represents for the most part of geologic time the continental margin facing to the east of the Pacific oceanic basin. Special remarks are drawn to the northern boundary between the South Asian Continental and the South Asian Intercontinental Domains, which lies, to the north of the Himalaya mountains, in the Yalutsangpo and the Indus valley. The boundary between the North Asian Intercontinental and the North Asian Continental Domains in the west Siberian lowand runs probably along the southern border of the Tobolsk massif and along the lower Obi north of the 60°N latitude. 3. The sedimentation types in stratigraphy as well as the related faunal provinces in Asia seem to bear some relation to the tectonic frame. The nature and disposition of the sedimentary basins show an obvious control exerted by the tectonic pattern of the time concerned. The Paleozoic regime dominated by an approximately latitudinal zonation is marked by a series of east-west trending sedimentary basins and related faunal provinces, and the thick sediments being poured into the Mesozoic and Cenozoic basins of various sizes in the Circum-Pacific Domain were likewise coatrolled by the Neocathaysian directrices.