Seminar

Traditionally, the North China Craton (NCC) was considered to be composed of uniform Archean-Paleoproterozoic basement overlain by Paleo-Mesoproterozoic unmetamorphosed cover. Since the late 1990’s, terrane accretion and collision models have been applied to the NCC, and now there is a broad consensus that the NCC formed by amalgamation of a number of micro-continental blocks. However, when and how these blocks were assembled to form the coherent basement remain unresolved, resulting in a variety of model for the subdivision and amalgamation of the NCC. The Trans-North China Orogen (TNCO) or the Central Orogenic Belt (COB) are in the similar position of the NCC, but researchers have different opinion about the collisional time (either Neoarchean or Paleoproterozoic). Researchers pay most attention to the southern part and the middle Part of the TNCO. However, the northern segment of the TNCO is still a weakly studied area. Therefore, my research focus on the metamorphic rocks from the northern part of the TNCO.

The Chengde Complex is located at the northern part of the TNCO, and metamorphic rocks mainly composed of granulite, amphibolite, paragneiss and TTG gneisses. Granulite and amphibolite generally occur as enclaves within paragneiss or TTG rocks, displaying as ‘blocks-in-matrix’ features. Most metamorphic rocks record clockwise P-T paths with isothermal decompression process, indicating they formed at an orogenic background. These rocks give metamorphic ages of 1914-1797 Ma, indicating it is a long-lived Paleoproterozoic orogen rather than a Neoarchean orogen.

Additional information: Ms. ZHANG Hui, u3006475@connect.hku.hk