郯庐断裂带的同造山运动

Synorogenic movement of the Tan-Lu fault zone

郯庐断裂带的起源时间与型式仍然存在着很大的分歧。最近在大别山东缘早白垩世左旋走滑韧性剪切带中 ,发现了早期左旋走滑韧性剪切带。其中三处早期糜棱岩中白云母分别给出了( 188.7± 0 .7)Ma、( 189.7± 0 .6 )Ma、( 192 .5± 0 .7)Ma的40 Ar/ 3 9Ar坪年龄 ,指示了同造山走滑热事件。前陆沉积与变形构造也表明该断裂带在华北与华南板块碰撞中就发生了活动。郯庐断裂带内的造山期构造及旁侧的前陆沉积与变形构造特征 ,指示断裂带同造山运动为转换断层型式 ,并将大别—苏鲁造山带左行错移了约 35 0km ,同时苏鲁造山带发生逆时针旋转。在早白垩世滨太平洋构造活动中 ,该断裂进一步向北延伸 ,发生了约 2 0 0km的左行平移。因而 ,该断裂带起源于华北与华南板块的碰撞之中 。

The origin timing and the model of the Tan-Lu fault are still debatable. It was found recently on the eastern margin of Dabie Mountains that the earlier sinistral strike-slip ductile shear belts exist in the Tan-Lu sinistral strike-slip ductile shear zone of the Early Cretaceous. Muscovite samples of mylonite from three localities in the earlier shear belts yield^(40)Ar/^(39)Ar plateau ages of (188.7±0.7) Ma, (189.7±0.6) Ma and (192.5±0.7) Ma, respectively. This dating indicates a synorogenic strike-slip thermal event. The foreland sediments and structures also show the activity of the fault zone during the collision of the North and South China plates. The synorogenic structures in the fault zone as well as the peripheral foreland sediments and structures demonstrate that the synorogenic motion of the fault zone was of a transform fault type, which sinistrally offset the Dabie and Sulu orogens for ca. 350 km and caused the anti-clockwise rotation of the Sulu orogen. During the activity of the fault zone in the Early Cretaceous, it extended further north and had left-lateral displacement of ca. 200 km. Therefore, the Tan-Lu fault was derived from the collision of the North and South China plates. Its synorogenic movement was associated with the continent-continent collision process of the two plates.