青藏高原冈底斯当穹错—许如错一带新近纪—第四纪地堑的基本特征

Basic characteristic of the Neogene-Quaternary graben in the Tangqung Co-Xuru Co area, Gangdise, Qinghai-Tibet Plateau

新近纪以来,印度板块-欧亚板块碰撞期后和抬升阶段发育的新构造和“老构造”的活化,在青藏高原冈底斯—念青唐古拉板片中主要表现为一系列南北向展布的张性构造带和北东、北西向展布的走滑断层,尤以南北向张性构造带活动最为明显,也是现今仍具强烈活动特点的构造带。当穹错-许如错南北向断裂带就是其中之一,由其控制的当穹错-许如错新近纪—第四纪地堑,南北长约190km,东西宽5～25km,由当穹错、当惹雍错、许如错3个子盆地组成。盆缘断裂的形成始于新近纪,第四纪全新世仍有活动,由差异升降导致盆地沉积中心在地堑中自南往北具有由东→西→东的变化趋势,地震、地热等活动南强北弱,反映了青藏高原具整体有限隆升、局部差异升降、新构造活动南强北弱的特点。

Since the Neogene, the reactivation of neotectonics and ＂paleotectonics＂, which occurred in the uplift stage after India-Eurasia collision, has been mainly manifested by a number of N-S extensional belts and NE- and NW-trending strike-slip faults, especially N-S extensional belts, in the Gangdise-Nyanqengtanglha slab on the Qinghai-Tibet Plateau, They are now tectonic belts with the characteristics of strong activities. The N-S-trending Tangqung Co-Xuru Co fault belt is one of these belts. The Neogene-Quatemary Tangqung Co-Xum Co graben controlled by the bek is -190 km long from north to south and 5-25 km wide from east to west and consists of the Tangqung Co, Tangra Yumco and Xuru Co subbasins. The basin-margin faults formed in the Neogene and were still active in the Holocene. Due to differential uplift and subsidence, the depocenter of the basin had a trend of change from east→west→east from south to north in the graben and activities such as earthquakes and geothermal activities were strong in the south and weak in the north, reflecting that the Qinghal-Tibet Plateau is characterized by limited wholesale uplift, localized differential uplift and subsidence and strong neotectonic activity in the south and weak tectonic activity in the north.