Continental growth of northwest China

Abstract

The northwest corner of China is the most interior part of Central Asia and includes parts of the Siberian, Tarim, and Kazakhstan plates where the Junggar and Tarim basins are separated by the east‐west trending Tianshan Range. A preliminary terrane map divides the area into thirteen separate areas which are classified into four types: (l) continental, (2) oceanic crust, (3) island arc, (4) composite. The boundaries for these terranes are faults that have been previously defined either by geologic mapping or Holocene activity. Passive consolidation of the southern margin of Paleo‐Asia is marked by accretion and subduction of the Paleo‐Tethys oceanic basins and by development of volcanic arcs. Paleomagnetic data indicate that the major plates and associated smaller terranes did not reach final consolidation until the Permian or later. The stratigraphic record reveals development of intracontinental basins in the late Carboniferous followed by the Pan‐Asian thermal event that gave rise to widespread intrusion of A‐type granites of late Paleozoic age. The frontal collision of India along the southern border of Asia in the Paleocene reactivated nearly all of the older major strike‐slip and thrust faults formed during the late Paleozoic consolidation of Paleo‐Asia. The complex nature of the continental growth of Central Asia has produced and destroyed many varieties of sutures, and reconstruction of the original plate and terrane configurations therefore is enigmatic.