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Quantifying Crustal Thickness in Continental Collisional Belts: Global Perspective and a Geologic Application
Fangyang Hu1,2, Mihai N Ducea2,3, Shuwen Liu4
1Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Peking University, Beijing, 100871, P.R. China.
Scientific Reports
|August 3, 2017
Summary
Geochemical data reveal how to track crustal thickness changes in continental collisional belts. This method was applied to the Qinling Orogenic Belt, showing distinct temporal variations in crustal thickness.
Area of Science:
- Geochemistry
- Tectonics
- Petrology
Background:
- Continental collisional belts provide insights into Earth's tectonic processes.
- Understanding crustal thickness evolution is key to deciphering orogenic histories.
- Geochemical proxies offer potential for reconstructing past geological conditions.
Purpose of the Study:
- To establish geochemical correlations between rock composition and crustal thickness in collisional settings.
- To investigate temporal variations in crustal thickness within the Qinling Orogenic Belt.
- To validate geochemistry as a tool for tracking crustal thickness changes in ancient orogens.
Main Methods:
- Compilation of geochemical data (Sr/Y and La/Yb ratios) from intermediate magmatic rocks.
- Correlation analysis between geochemical ratios and modern crustal thickness.
- Application of established correlations to reconstruct past crustal thickness in the Qinling Orogenic Belt.
Main Results:
- A robust correlation was found between whole-rock Sr/Y and La/Yb ratios and crustal thickness.
- Crustal thickness in the North Qinling Belt remained stable (~45-55 km) from the Triassic to Jurassic.
- The South Qinling Belt experienced significant crustal thickening (~60-70 km) around 215 Ma, followed by thinning.
Conclusions:
- Geochemical proxies (Sr/Y and La/Yb) are effective for reconstructing crustal thickness in continental collisional belts.
- The study provides a detailed temporal record of crustal thickness variations in the Qinling Orogenic Belt.
- Combining data from collisional belts and subduction arcs offers a comprehensive view of orogenic evolution.
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