Mối quan hệ giữa hoạt động kiến tạo vùng và cấu trúc vỏ trái đất ở cao nguyên Tây Tạng phía Đông được phát hiện thông qua dị thường trọng lực

Xiao Xu1,2, Rui Gao2, Xiaoyu Guo2
1SinoProbe Center, Chinese Academy of Geological Sciences, Beijing, China
2Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China

Tóm tắt

Cao nguyên Tây Tạng phía Đông đang nhận được nhiều sự chú ý hơn nữa vì nơi đây kết hợp các đứt gãy hoạt động, sự nâng lên và những trận động đất lớn trong một khu vực đông dân cư. Dựa trên các nghiên cứu trước đây, hầu hết các hoạt động kiến tạo trong kỷ Đệ tứ đều liên quan đến cấu trúc vùng của các khối địa phương trong quy mô vỏ trái đất. Do đó, việc hiểu rõ hơn về cấu trúc vỏ trái đất của các khối kiến tạo vùng là một chủ đề quan trọng cho các nghiên cứu tiếp theo. Trong bài báo này, chúng tôi đã kết hợp dị thường trọng lực Bouguer đơn giản với độ sâu Moho từ các nghiên cứu trước đó để điều tra cấu trúc vỏ trái đất trong khu vực này. Để làm nổi bật các cấu trúc vỏ, dị thường trọng lực do địa hình Moho gây ra đã được giảm thiểu thông qua các tính toán mô hình tiến. Một đạo hàm tổng hợp (THD) đã được áp dụng cho các phần dư trọng lực. Kết quả cho thấy phần dư trọng lực của vỏ trái đất tương thích với địa hình và cấu trúc địa chất của các khối vùng, bao gồm lưu vực Tứ Xuyên, lưu vực Chuxiong, đứt gãy Xiaojiang và đứt gãy Jinhe, cũng như vùng đứt gãy Longmenshan. THD nhấn mạnh rìa phía tây của khối Dương Tử, tức là vùng đứt gãy Longriba và đứt gãy Xiaojiang cắt ngang qua khối Dương Tử. Mô hình bàn cờ của phần dư trọng lực trong đới gập Songpan-Garze và mảnh đất Chuandian cho thấy vỏ trái đất đang trải qua một sự ép ra phía nam và theo hướng Đông Nam, điều này phù hợp với hướng chảy mà các phép đo GPS cho thấy. Qua việc tích hợp các diễn giải, cơ chế kéo dài theo từng bước của cao nguyên Tây Tạng phía Đông được hỗ trợ bởi sự biến dạng vỏ trái đất theo hướng Đông Nam, và sự ép ra của mảnh đất Chuandian được thực hiện thông qua đứt gãy Xianshuihe.

Từ khóa

#Cao nguyên Tây Tạng #hoạt động kiến tạo #dị thường trọng lực #cấu trúc vỏ trái đất #Moho #vùng đứt gãy.

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