下扬子区印支-早燕山期的构造特征及应力场模拟

Tectonic Characteristics and Numerical Stress Field Simulation in Indosinian-Early Yanshanian Stage,Lower Yangtze Region

在深入探讨下扬子区印支—早燕山期构造变形特征的基础上,应用SHELLS有限元方法模拟了该时期下扬子区的构造应变率和块体位移速率。结果表明:秦岭—大别造山带与郯庐断裂相接地带为强压应力区,南黄海东部为强张应力区,而苏鲁造山带及江绍断裂带为压扭应力区。下扬子地块应变率大小为5.0×10-15/s～1.0×10-14/s,块体位移速率约50mm/a。在该应力场控制下,下扬子地块表现出大规模的南北"对冲"推覆构造样式。

Based on intensive research on the tectonic deformation characteristics in Indosinian-Early Yanshanian stage in the Lower Yangtze region,this paper has simulated the tectonic strain rate and surface velocity through the＂thin-shell＂finite element method.The modeling results indicate that the area around the junction between Qinlin-Dabie Orogen and Tanlu fault suffered intensively compressional effect,the eastern South Yellow Sea was a strongly tensional area,while the Sulu orogen and the Jiangshao fault were transpressional areas.The average strain rate of the Lower Yangtze region was about 5.0×10 -15 /s^1.0 ×10 -14 /s and the surface velocity was probably about 50 mm/a.Controlled by this kind of tectonic stress field,the Lower Yangtze Block produced massive thrust nappe structures in a ramp style.