摘要
Detailed characterization of diagenetic fluid behaviour and evolution is commonly hindered by shortage of appropriate and economic methods to carry out in situ analysis in the tiny diagenetic mineral crystals. Using micromill sampling method, this study presents in situ stable isotopic data for the growth zones of saddle dolomite crystals in the hydrothermally-altered dolostones of Upper Cambrian (Furongian) at Keping, Tarim Basin, NW China. These data show minor and large variations in δ13C ( 0.7‰ to 1.5‰ VPDB) and δ18O ( 8.3‰ to 13.8‰ VPDB), respectively, from the cores to outer rims of the dolomite crystals and suggest that saddle dolomites precipitated from dolomitizing fluids with similar carbon sources but oscillatory temperatures during different formation stages. This scenario is confirmed by microthermometry of fluid inclusions within the growth zones of dolomite crystals. This study indicates that in situ isotope analysis could provide more detailed information related to the source and pathway of dolomitizing fluids, facilitating better characterization of dolomitizing fluids and processes.
Detailed characterization of diagenetic fluid behaviour and evolution is commonly hindered by shortage of appropriate and economic methods to carry out in situ analysis in the tiny diagenetic mineral crystals. Using micromill sampling method, this study presents in situ stable isotopic data for the growth zones of saddle dolomite crystals in the hydrothermally-altered dolostones of Upper Cambrian （Furongian） at Keping, Tarim Basin, NW China. These data show minor and large variations in δ^（13）C （-0.7‰ to -1.5‰ VPDB） and δ^（18）O （-8.3‰ to -13.8‰ VPDB）, respectively, from the cores to outer rims of the dolomite crystals and suggest that saddle dolomites precipitated from dolomitizing fluids with similar carbon sources but oscillatory temperatures during different formation stages. This scenario is confirmed by microthermometry of fluid inclusions within the growth zones of dolomite crystals. This study indicates that in situ isotope analysis could provide more detailed information related to the source and pathway of dolomitizing fluids, facilitating better characterization of dolomitizing fluids and processes.
基金
supported by SINOPEC(G5800-07-ZS-WX032)
the National Key Scientific Special Program of China(2008ZX05008-003-002 and 2011ZX05008-003-10)
the National Basic Research Program of China(2012CB214802)
the State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation at CDUT(PL200801)
关键词
白云岩化
流体行为
塔里木盆地
稳定同位素
原位分析
水热蚀变
柯坪
起源
Tarim Basin
Upper Cambrian
saddle dolomite
micromill sampling
in situ stable isotope analysis
fluid inclusionmicrothermometry
petrography
