南秦岭武当—桐柏地区碱性岩研究

    ALKALINE ROCKS IN THE WUDANG-TONGBAI AREA SOUTHERN QINLING

    • 摘要: 南秦岭武当—桐柏地区的碱性岩,按空间分布可分为南北两个带。南带岩石碱度及Nb、REE丰度明显高于北带。本文着重对南带四个岩体,即花山寨英碱正长岩、观子山硬玉钙霞正长岩,杀熊洞碱闪岩—钙霞正长岩—霓石碳酸岩杂岩体以及庙垭正长岩—黑云母方解碳酸岩—铁白云石碳酸岩杂岩体的岩石学、矿物学、地球化学、时代及岩石成因进行研究。其成岩时代为215~306Ma,海西—印支期。观子山、杀熊洞和庙垭岩体成岩物质来源于上地幔,而花山寨岩体则主要与下部地壳物质有关。

       

      Abstract: Alkaline rocks in the Wudang-Tongbai area of the Southern Qinling Mountains can be divided into the southern and northern zones based on their spatial distribution. The alkalinity and Nb and REE abundances of the rocks in the southern zone are apparently higher than those in the northern zone. This paper focuses on the petrology, mineralogy, geochemistry, ages and petrogenesis of four alkaline rock bodies in the southern zone, which are the Huashanzhai nordmarkite, Guanzhishan jadeite-carcrinite syenite. Shaxiongdong alkaline amphibolite-cancrinite syenite-aegirine carbonatite complex and Miaoya syenite-biotite alvikiteankeritic carhonatite complex. Ages of the foar rock bodies have been determined with U-Ph, K-Ar and Rb-Sr methods to he 215—306 Ma, suggesting that they were formed in the Hercynian-Indosinian. On the basis of isotopic studies of 87Sr/88Sr, δ18O,δ13C and δD, it may be concluded that rock-forming materials of the Guanzhishan, Shaxiongdong and Miaoya rock bodies were derived from the upper mantle, while the genesis of the Huashanzhai rock body is mainly related to the lower crust materials.

       

    /

    返回文章
    返回