Pressure—Temperature Contours and PT Paths of the Early Precambrian Rocks through the Yinshan Area and Their Implication to the Crustal Evolution

Abstract

Four distinct litho‐tectonic belts (zones) in the Yinshan area, North China, were identified by pressure‐temperature contours and litho‐tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan‐Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo‐tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan‐Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo‐tectonic settings.