胶东半岛乳山地区低角度韧性剪切带几何学、运动学特征:对中国东部岩石圈减薄作用的启示

Geometrical and kinematic characteristics of low angle ductile shear zone in Rushan area of Jiaodong Peninsula and their implications for lithospheric thinning in eastern China

大规模伸展构造是华北克拉通东部岩石圈减薄的重要表现形式。部分低角度韧性剪切带是地壳伸展变形后所展现的构造形式。本文研究了王格庄韧性剪切带的岩石学、几何学、运动学等特征显示:韧性剪切带走向近南北向,剪切带断层面倾向多变(倾向西、西南、西北方向)。大部分区域面理低角度倾向西,矿物拉伸线理近东西向,不对称旋转碎斑及S-C组构指示顶端指向西的剪切特征。结合研究区西侧与伸展构造相匹配的半地堑伸展盆地证据:本研究认为伸展构造的形成可能与西太平洋板块的后撤相关,即大规模伸展构造作用引发了华北克拉通东部的地壳减薄作用。

Large-scale extensional tectonic is an essential manifestation of lithospheric thinning in the eastern North China Craton. Part of the low-angle ductile shear zone is a structural exhibition after crust deformation. In this paper, we decipher the petrological, geometric, and kinematic features of the Wanggezhuang ductile shear zone, showing that: the shear zone strikes N-S with several dipping directions(W, SW, and NW). Most of the foliation dips to the west at a low dipping angle, mineral stretching lineations plunge to W at low plunge angle;Asymmetric rotational porphyroclast and S-C fabrics indicate a top-to-west shearing.Integrating evidence of half-graben extensional basin matched with extensional structure from the west of the shear zone: we presented that the extensional event was produced by the retreat of the Paleo-pacific plate, that is, huge extensional structural result in crustal thinning in North China Craton.