Structural and tectonic evolution of orogenic belts, with an emphasis on kinematics of shear zones, accretionary/collisional orogens and Archean tectonics

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The long term goal of my research is to develop a stronger understanding of structural and tectonic evolution of mountain belts, the evolution of tectonic processes through time, and the structural and tectonic control on mineralization. The proposed study will focus on three ancient mountain belts of contrasting ages and styles: the Proterozoic to Mesozoic South China Block and the Paleozoic Central Asian Orogenic Belt (CAOB) in China and the Archean Superior craton in Canada. Continental margins, especially passive margins, commonly have irregular shapes and exhibit promontories and reentrants. Where this is the case, collision between two continents is expected to start at a promontory or between two promontories. This has major implications for tectonic evolution of orogens, but has drawn only limited attention. A better understanding of the role of irregular continental margins in collision through a study of the Early Paleozoic Orogen in South China is one of the objectives of the proposed study. Promontory collision offers a solution to the biggest puzzle concerning South China in the early Paleozoic, that is, a major tectono-thermal event in South China, with characters of a collisional orogeny, took place tens of millions of years after the Gondwana supercontinent had been assembled and collision appeared to have been over. Our work in the CAOB will focus on the timing and processes of the final closure of the Paleo-Asian Ocean, through a detailed study of a Carboniferous-Permian volcano-sedimentary sequence and syntectonic intrusions and a potential ophiolite sequence. We will also pay special attention to the geometry, kinematics, temporal evolution and the tectonic significance of major terrane-bounding shear zones. Our work on the Superior craton has led to the recognition of evidence for both vertical and horizontal tectonism and, more importantly, for their synchronous operation. We have proposed that synchronous vertical and horizontal tectonism was an important process in the Neoarchean and represented a transition from dominant vertical tectonism in the Meso-(and Paleo-?) Archean to dominant horizontal tectonism in the Proterozoic and Phanerozoic. We will continue to test these interpretations and their general applicability. Our field-based study will be aided by numerical modelling, using a new code developed by our team that covers the time component by solving a generalized non-steady system with finite element method. The code is optimal for simulating geological processes with large deformation and for examining structural evolution in complex orogenic processes. These research efforts will train at least five graduate and many more undergraduate students in structural geology and tectonics. They will gain a competitive edge from our field-based, multidisciplinary and collaborative research experience.