The depth of the continental deep subduction is of vital importance for better understanding of the dynamics of exhumation process of ultrahigh pressure metamorphic rocks in the continental collision orogen belt. The crystal of α-PbO2-type TiO2 was found in omphacite from coesite-bearing eclogite at Shima in the Dabie Mountains, China. A natural ultrahigh-pressure phase of titanium oxide with α-PbO2-structure has been identified through high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectrometer (EDS) in jadeite quartzite at Shuanghe in the Dabie Mountains, China. The reservation of nano-scale lamellae of the α-PbO2-type polymorph of TiO2 provides a new evidence of ultra high-pressure, metamorphism at 6-7 GPa, 730-870°C. It implies a burial of continental crustal rocks to depth between 170-200 kilometers or deeper, and also implies exhumation of subducted continental crust to the Earth's surface was presumably rapid, though at an uncertain rate.
|Number of pages||10|
|Journal||Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences|
|Publication status||Published - Sep 2008|
- Dabie Mountains
- High-resolution transmission electron microscope
- TiO UHP polymorphs
- UHP metamorphism