The Geochemistry fea-tures and zircon LA-ICP-MS U-Pb Ages of the volcanic rocks from the Pre-Devonian strata in Dayaoshan area,North Guangdong Province
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摘要: 通过1︰5万地质填图及剖面测制,作者在粤北大瑶山地区的震旦-寒武纪地层中首次发现多层火山岩,岩性主要为火山-沉积碎屑岩类的变质凝灰质不等粒岩屑石英砂岩、变质凝灰质不等粒长石石英砂岩、沉凝灰岩等,局部见变流纹质熔结凝灰岩。对变流纹质熔结凝灰岩、变质凝灰质砂岩用 LA-ICP-MS 法测定锆石 U-Pb 年龄,206Pb/238U 年龄介于614~2869 Ma 之间,年龄值较为分散,说明碎屑锆石是多来源的。火山岩年龄数据与地层时代归属矛盾,粤北大瑶山地区前泥盆纪地层的时代归属值得进一步探讨。
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关键词:
- 前泥盆纪地层 /
- 火山岩 /
- 锆石 U-Pb 定年 /
- 大瑶山地区 /
- 粤北
Abstract: By 1: 50000 geological mapping and measured sections, the first discovery of multi-layer volcanic rock in Sinian-Cambrian strata in Dayaoshan area, North Guangdong Province. Those volcanic rocks are mainly com-posing of volcano-sedimentary clastic rocks including metamorphic tuffaceous inequigranular lithic quartz sand-stone, metamorphic tuffaceous inequigranular feldspar quartz sandstone, sedimentary tuff, locally variable rhy-olitic ignimbrite. The zircons from variable rhyolitic ignimbrite, metamorphic tuffaceous sandstone were deter-mined by LA-ICP-MS method, and yielded 206Pb/238U ages of 614 ~ 2869 Ma, the dispersed ages indicated the detrital zircons are of multi sources. The difference between zircon U-Pb ages and strata formation time indicated that the formation age of Pre-Devonian strata of Dayaoshan area, Northern Guangdong Province need further re-search.-
Key words:
- Pre-Devonian strata /
- volcanic rocks /
- zircon U-Pb dating /
- Dayaoshan area /
- North Guangdong Province
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