Sequence Stratigraphy and Tectonic Environment of the Chartai Group,Inner Mongolia

The Middle Proterozoic Chartai Group separated by two unconformities consists of three depositional se-quences: the Shujigou Formation-Zenglongchang Formation (DS Ⅰ), the Agulugou Formation (DS Ⅱ), andthe Liuhongwan Formation (DS Ⅲ). The carbonate platform and back-platform basin are the basic environ-ment model of the Chartai Group. The syndepositional faults on the oceanward side of the carbonate platformand large-scale slumping in the soft sediments are important marks of facies tracts. The newly establishedZenglongchan uplifting, an epeirogenetic uplifting, plays an important role in the formation of thepalaeogeographic framework of the Chartai Group. The stratigraphic correlation between the Chartai Groupand the Bayan Obo Group is made for the first time by using sequence stratigraphic principle and model estab-lished by P.R. Vail. The Chartai Group, which was deposited on the northern passive continental margin of theNorth China platfom, represents the platform cover.

江苏响水至内蒙满都拉地学断面南北两段的地质观察

华北地台西北角是地台基底固结最迟的一片,其中渣尔泰群代表拗拉槽沉积,而白云鄂博群槽地则反映地斜性质,两者都约在14亿年前色尔腾运动中褶皱回返并入华北地台基底。苏北—胶南地体夹持于华北和扬子克拉通之间。根据兰片岩带的发育、超镁铁岩和榴辉岩的广布以及韧性剪切带与弱应变域相间排列的构造格局,提出了一个反映板块碰撞、缝合的构造模型。

内蒙古乌拉特中旗赛音呼都格地区渣尔泰群构造演化特征

乌拉特中旗赛音呼都格地区渣尔泰群经历了两期构造变形:早期(主期)褶皱样式为不协调褶皱,发育大型的同斜褶皱,构造应力场方向为NWW-SEE向;晚期褶皱以宽缓弯曲的形式,横跨叠加在主期褶皱之上,主要表现为轴面面理在走向和倾向上的波状弯曲,区域主压应力为近EW向。