标题:
广东从化石岭碱性杂岩体角闪石正长岩LA-ICP-MS锆石U-Pb定年LA-ICP-MS Zircon U-Pb Dating of Hornblende Syenite form Shiling Alkaline Complex, Conghua City, Guangdong Province
作者:
李宏卫, 林小明, 黄建桦
关键字:
从化市, 碱性杂岩体, 角闪石正长岩, LA-ICP-MS锆石U-Pb定年Conghua City, Alkaline Complex, Hornblende Syenite, LA-ICP-MS Zircon U-Pb Dating
期刊名称:
《Advances in Geosciences》, Vol.5 No.2, 2015-04-09
摘要:
广东从化石岭碱性杂岩体呈东西向展布，出露面积约9 km2，属于南岭近东西向构造——岩浆岩带之佛冈岩浆岩带，岩体主要由角闪石正长岩和方钠石正长岩组成，是省内发现的唯一的碱性侵入岩体，该区也是广东乃至华南地区重要的正长岩非金属矿产地。对石岭碱性杂岩体角闪石正长岩进行LA-ICP-MS锆石U-Pb定年，获得其结晶年龄为125.3 ± 3.5 Ma (MSWD = 2.6, n = 13)，为早白垩世岩浆活动的产物。其成岩作用与早白垩世岩石圈强烈伸展构造背景下的地幔物质上涌密切相关。该年龄指示从化地区岩石圈发生伸展作用的时间为早白垩世。
The Shiling alkaline complex in Conghua city, Guangdong province, extending from east to west, with about 9 km2 exposed area, belongs to the Fogang magmatite belt, which is one of the three nearly EW trending Tectonic and Magmatite Belt in Nanling area. It is mainly composed of hornblende syenite and sodalite syenite, is the only found alkaline intrusive rock mass in Guang-dong province, and this area is an important syenite non-metallic mineral deposits in Guangdong and even Southern China. The LA-ICP-MS zircon U-Pb age of hornblende syenite from Shiling alka-line complex is 125.3 ± 3.5 Ma (MSWD = 2.6, n = 13), and it shows the emplacement age of Shiling alkaline complex belonged to the early Cretaceous. The diagenesis is closely related to the mantle upwelling in strong lithospheric extensional tectonic background in early Cretaceous. The isotopic age with high precision indicates that the time of lithospheric extension in Conghua area was early Cretaceous.