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作为理解华南构造演化的关键地区,在华南板块南缘的云开地体和越北的Song Chay地体发育了早中生代的向北东逆冲推覆的韧性变形。在云开地体,经历角闪岩相和绿片岩相变质的矿物指示了产状平缓的面理上发育明显的北东—南西向矿物拉伸线理。沿着这些矿物拉伸线理,具有上部指向北东的剪切变形。同位素年代学的定年结果指示了变形事件发生在220 Ma左右。在越南北部,Song Chay地体的岩石和构造特征与云开地体极其相似:平缓的面理,北东—南西向的矿物拉伸线理和上部指向北东的剪切变形是其主要的构造特征,这些构造特征均表现为向北东的逆冲推覆,变形时间从晚三叠世至早侏罗世。这期构造事件的动力学机制被认为同印支板块与华南板块晚古生代—早中生代的构造拼合密切相关。我们认为新发现的Song Chay蛇绿混杂带是华南板块同印支板块的碰撞拼合界线。因此,华南板块南缘云开地体和Song Chay地体被一同卷入同印支板块的碰撞造山体系之中。
As a key area for understanding the tectonic evolution in South China, ductile deformation of the Early Mesozoic to the North East thrust nappe developed in the Yunkai terrane in the southern margin of South China Plateau and Song Chay terrane in Vietnam. In the cloud-open terrane, the minerals undergoing amphibolite facies and greenschist facies indicate the apparent flattening of the northeaster-southwest mineral extension lineage. Along these mineral stretching lines, there is shear deformation with the upper part pointing to the north-east. The dating results of isotopic chronology indicate that the deformation event occurred at about 220 Ma. In the northern part of Vietnam, the Song Chay terrain has similar rock and tectonic characteristics to those of the open cloud: gentle physiognomy, north-south-west mineral stratification, and upper-east shear deformation are the dominant These tectonic features are all characterized by thrusting to the northeast, with deformation time ranging from Late Triassic to Early Jurassic. The kinetic mechanism of the tectonic events in this period is considered to be closely related to the structural assemblage of the Late Paleozoic-Early Mesozoic in the Indo-China Plate and the South China Plate. We think the newly discovered Song Chay ophiolite belt is the collision and consolidation boundary between the South China Plate and the Indo-China Plate. Therefore, the Yunkai terrane and the Song Chay terrane in the southern margin of the South China Plate are involved in the collision orogeny of the same member of the Indo-China Plate.