An excellent fossil wood cell texture with primary uranium minerals at a sandstone-hosted roll-type uranium deposit, NW China

A fossil wood cell texture with pitchblende and coffinite found at a sandst one-hosted roll-type uranium deposit, Xinjiang, NW China, is first reported here for the country. In the mineralized sandstone, detrital grains consis ting of quartz, feldspar. rock fragments, carbonaceous trashes, mica and ac cessory minerals were deposited in early Turassic time and were cemented by clays and minor authigenic calcite and quartz. Pitchblende and minor coffi nite are principal ore minerals at the deposit, and selectively replaced ca rbonized fossil wood remnants or filled fossil wood cells. An excellent fos sil wood cell texture with primary uranium minerals formed. Replacement of organic debris by primer?; uranium minerals may be due to a local reducing environment resulting from the production of CH4, H2S or H2SO3 in its decom position. and a biochemical reaction indicated by the common presence of fr amboidal pyrite. (C) 2001 Elsevier Science B.V. All rights reserved.