2009 28 (4):  445-450    ISSN: 1004-5589:  CN: 22-1111/P Sedimentary characteristics and its environment of Early Cretaceous Yixian Formation in Senjitu Basin, northern Hebei DONG Xu-Ming, GONG En-Pu, CHEN Deng-Hui, LIANG Jun-Hong, GUAN Chang-Qing, BAI Xue-Song, LI Yong-Jie Institute of Geological Resources and Engineering, N ortheastern University, Shenyang 110004, China Received 2009-08-27  Revised 2009-11-15  Online 2009-12-25 Reference   Corresponding author: