THE MODERN DOLOMITE DISCOVERY AND SIGNIFICATION AT WEIZHOU ISLAND GUANGXI PROVINCE

The bioclastic limestone, most of which consist of coral fragment, is sedimented at northwest beach of the Weizhou Island, Guangxi A dolomite was discovered in its intergranular space. The age of bioclastic limestone, determined by C14, is about 2120 ± 90 years. The dolomite formed perhaps later than it. So it ought to belong to modern dolomite. The dolomite possesses variant crystal size, most of which are about 2-0.5mm. The crystal is perfect clear, transparent, and most of them are the aggregate form. The dolomite is characterized by optic monoaxial crystal negative optic character, No=1.678 Ne =1.514. specific gravity-equals 3.1, hardness equals 4. The dolomite was deiinitely testified by staining method, differential thermal analysis, infrared spectrometry and X-ray. According to lower much value of the δ13C , δ13C and seeping diagenetic environment in which the bioclastic limestone exists. we can firmly belive that the dolomite formed under the condition where mixed fresh water in to sea water.