摘要
华北地区可划分出2个岩石圈尺度的构造单元:西面的鄂尔多斯克拉通块体和东部的华北裂谷盆地。华北裂谷由主体的似环状盆地和周边山岭组成,还有大的似环状盆地中央的苏鲁淮山岭。华北裂谷盆地,在古近纪(E)和新近纪(N)—第四纪(Q)时期分别通过主要的纯剪切(pureshearing)和分布剪切(distributedshesring)(均含简单剪切组分)变形机制形成,它们导源于软流圈上涌诱发的巨大岩石圈减薄作用。然而,鄂尔多斯块体周边的断陷盆地带则是通过简单剪切(simpleshearing)变形机制形成,它们导源于鄂尔多斯克拉通块体的隆升和作用于鄂尔多斯南缘的六盘山与来自青藏高原碰撞带的北东向挤压力的联合作用。新生代时期,在快速的岩石圈大幅度减薄的时期内,华北地区东部向东伸展的速率比西部的鄂尔多斯块体大得多,它暗示软流圈物质向东的流动可能主动地拖拉着上覆岩石圈向东移动。可能有3条这样的通道,允许青藏碰撞带下面的软流圈物质向东流动,它们是:(a)高原南部过松潘—甘孜、三江达南海;(b)高原北部经六盘山、鄂尔多斯周边和华北—东北平原达日本海;(c)帕米尔经天山、蒙古西部、贝加尔达鄂霍次克海。
Two lithospheric-scale tectonic units may be distinguished in North China： the circular North China rift and its surrounding mountain ranges in the east and the Ordos cratonic block and its surrounding elongated down-faulted basins in the west. The former consists of the main quasi-circular basins and surrounding ranges, as well as the mountain ranges in Jiangsu and Shandong in the central part of the large quasi-circular basin. The North China rift basins formed mainly by pure shearing and distributed shearing （both of which contain simple shear components） deformation mechanisms during the Paleogene and Neogene-Quatemary respectively. They originated by the combined action of the uplift of the Ordos cratonic block and NE-directed compression on the Liupan Mountains at the southem margin of Ordos from the Qinghai-Tibet Plateau collision zone. In the Cenozoic, during the rapid extensive lithospheric thinning, the rate of the E-directed extension in the eastem North China region was much higher than that in the Ordos block in the west, which implies that the eastward flow of the asthenospheric material may have actively dragged the overlying lithosphere eastward. There might be three passageways to allow the eastward flow of the asthenospheric material below the Qinghai-Tibet collision zone： （a） from the southem part of the plateau through Songpan-Garze and Sanjiang （which refers to the Lancang, Nujiang and Jinsha rivers flowing in eastem Tibet, southwestem Sichuan and westem Yunnan） to the South China Sea, （b） from the northern part of the plateau through the Liupan Mountains, peripheries of Ordos and Northeast China plain to the Sea of Japan, and （c） from Pamir through the Tianshan Mountains, westem Mongolia and Baikal to the Okhotsk Sea.
出处
《中国地质》
CAS
CSCD
2006年第4期751-761,共11页
Geology in China
基金
国土资源部重点科技专项计划项目(20001010202)
国家自然科学基金会重点基础项目(40234048)
国家自然科学基金会项目(40572048)
科技部IGCP国际合作项目(2001cb711002)联合资助。
关键词
华北
岩石圈伸展减薄
软流圈侧向流动和上涌
机制与过程
North China
lithospheric extension and thinning
asthenospheric lateral flow and upwelling, mechanism and process
