摘要
湖北杀熊洞碳酸岩杂岩体位于南秦岭武当地块西南缘,侵入于中元古界武当群。该岩体由辉石碱闪岩、混染含霞正长岩、斑状钙霞正长岩、钠质正长岩和黑云霓石碳酸岩组成,各种岩石类型具有相似的地球化学特征,说明它们为同源岩浆产物。经Rb-Sr和K-Ar法测定,成岩时代为225—305Ma。黑云霓石碳酸岩δ^(18)O=6.34—6.72％,δ^(13)C=—5.54——5.63‰,^(87)Sr/^(86)Sr(i)=0.7032,证明其物质来源于上地幔。方解石形成温度为398—570℃,形成霓石的压力为12.4×10~5kPa。
The Shaxiongdong biotite-aegirine carbona ite complex located on the southwestern margin of the Wudang massif in the South Qinling Fold Belt and intruded into the Middle Proterozoic Wudang Group. The complex was dated at 305 Ma by the Rb-Sr isochron method on biotite-aegirine carbonatite hosted in it.According to the mineral composition and texture of rocks, the complex can be divided into five rock types: pyroxene alkalic amphibolite, contaminated cancrinite-bearing syenite, porphyritic cancrinite syenite, soda syenite and biotite-aegirine carbonatite.Geochemical behaviours of REE and other trace elements in the five rock types are much the same, suggesting that they were derived from the same source region.On the basis of the occurrence, and δ18O(+6.34-+ 6.72‰), δ31C(-5.54-5.63‰) and87Sr/86Sr(i)(0.7032) of the biotite-aegirine carbonatite, it is evident that the complex-forming materials were derived from the upper mantle.Calcite-forming temperature in the biotite-aegirine carbonatite was estimated at 398-570℃ and aegirine-forming pressure at about 12.4×105kPa.
出处
《地球化学》
CAS
CSCD
北大核心
1991年第3期245-254,共10页
Geochimica
