南海的“山根拆沉成因观”——南海成因新议

南海成因问题至今仍众说纷纭。作者以寻求南海形成演化的内因为着眼点，在大量地震剖面地质解释的基础上，运用构造解析法对南海南北陆缘前新生代基底地质构造变形形迹进行了系统的构造恢复和组合分析，发现了残存于南海南北陆缘中生代基底中的断层褶皱具有碰撞造山带特有的背冲断褶构造特征，指出该古造山带的中轴位置大致沿现今双峰笔架海山连线分布，并称之为古双峰笔架碰撞造山带。结合南海地区新生代岩浆岩地球化学特征分析和南北陆缘新生代伸展构造特征分析，提出该造山带在新生代发生了山根拆沉的解体过程，并明确提出了该“山根拆沉”机制是诱发南海形成的根本原因。

"MOUNTAIN ROOT DELAMINATION":A NEW MECHANISM FOR ORIGIN OF THE SOUTH CHINA SEA

The origin of the South China Sea (SCS) still remains a dispute. With emphasis on internal mechanisms for the formation and evolution of the SCS, based on geological interpretation of a large number of seismic profiles, and using tectonic analysis as the method, the authors carried out systematic tectonic restoration of the structural deformation features of the Pre Cenozoic basements on the northern and southern continental margins of SCS. Back thrust fold structures are found remained in the basements, which are endemic to collision orogenic belt. The axis of the paleo orogenic belt is distributed roughly along the modern Shuangfeng Bijia seamount line. We name it "Paleo Shuangfeng Bijia collision orogenic belt" hereafter in this paper. Together with the analyses of Cenozoic magmatite geochemical characteristics of SCS region and the Cenozoic extensional tectonic characteristics of northern and southern continental margins, the authors proposed that the orogenic belt underwent a mountain root delamination process in Cenozoic. And the mechanism of "mountain root delamination" is the fundamental origin of the SCS.