1. University of Alabama, Department of Geological Science, Tuscaloosa, Alabama 35401, USA.(corresponding author).
2. University of Alabama, Department of Geological Science, Tuscaloosa, Alabama 35401, USA and China University of Petroleum (Beijing), School of Geosciences, Beijing, China..
3. China University of Petroleum (East China), School of Geosciences, Qingdao 266580, China..
4. Sinopec Petroleum Exploration and Production Research Institute, Haidian, Beijing 100086, China..