Rare Earth Elements in Hydrothermally Altered granitic Rocks in the Ranong and Takua Pa Tin-Field, Southern Thailand
Rare Earth Elements in Hydrothermally Altered granitic Rocks in the Ranong and Takua Pa Tin-Field, Southern Thailand
复制标题
泰国南部拉廊和达瓜巴田田热液蚀变花岗岩中的稀土元素
DOI：
10.1111/j.1751-3928.2012.00212.x
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发表时间：
2013
期刊：
影响因子：
1.4
通讯作者：
Akira Imai
中科院分区：
文献类型：
--
作者：
佐藤雄二;松永栄一;内田成明;Akira Imai
本文对泰国南部Ranong和Takua Pa锡田的热液蚀变花岗质岩石进行了地球化学研究，探讨了稀土元素的赋存模式，重点研究了东南亚锡带花岗质岩石中潜在的稀土资源。拉浓锡田Haad Son Paen（目前开采高岭土）蚀变花岗质岩石的总REE （ΣREE）含量在130 ~ 350 ppm之间，Takua Pa锡田Nok Hook蚀变花岗质岩石和高岭石脉脉的REE含量分别高达424 ppm和872 ppm。蚀变花岗质岩石和高岭石脉脉中的稀土元素呈现相对扁平的球粒陨石正规化模式，与原始花岗质岩石及其风化壳相比，稀土元素富集于重稀土元素。在Nok Hook (Takua Pa)，从蚀变花岗质岩石中分离出的高岭石ΣREE含量为1313 ppm， ΣREE含量约为蚀变花岗质岩石整体组成的4倍。浸出高岭石和蚀变花岗岩的球粒陨石归一化稀土模式相对平坦。连续萃取实验表明，蚀变花岗岩和高岭石细脉中分别有41%和85%的稀土元素以离子交换形式存在。此外，高岭石细脉中90%以上的稀土元素以酸溶态存在。另一方面，Haad Som Paen （Ranong）蚀变花岗质岩石中高岭石细脉和富集高岭石的ΣREE含量分别为70 ppm和75 ppm，因此高岭石中REE富集未得到证实。此外，通过序次提取实验，在Haad Som Paen蚀变花岗岩和高岭石脉脉中分别提取了23%和4%的稀土元素。在Haad Som Paen蚀变花岗岩中，稀土元素以难熔相形式存在，酸溶态稀土元素被热液浸出。
Geochemical studies were conducted on the hydrothermally altered granitic rocks in the Ranong and Takua Pa tin‐fields in southern Thailand in order to investigate the mode of occurrence of REE (rare earth elements), with emphasis placed on a potential REE resource associated with granitic rocks in the Southeast Asian Tin Belt. The total REE (ΣREE) content of altered granitic rocks ranges from 130 to 350 ppm at Haad Son Paen (which is presently mined for kaolin clay) in the Ranong tin‐field, and that of altered granitic rocks and kaolinite veinlets reaches up to 424 ppm and 872 ppm, respectively, at Nok Hook in the Takua Pa tin‐field. Rare earth elements in the altered granitic rocks and kaolinite veinlets show a relatively flat chondrite‐normalized pattern, thus enriched in heavy REE compared with the original granitic rocks and their weathered crusts. At Nok Hook (Takua Pa), the ΣREE content of kaolinite separated from an altered granitic rock by elutriation is 1313 ppm, a ΣREE amount about four times higher than that of whole‐rock composition of the altered granitic rock. Chondrite‐normalized REE patterns of the elutriated kaolinite and of the altered granite are relatively flat. Sequential extraction experiments suggest that 41 and 85 percent of REE are present as ion exchangeable‐form in the altered granitic rock, and in the kaolinite veinlets, respectively. In addition, more than 90% of REE in the kaolinite veinlets are present as the acid‐soluble state. On the other hand, the ΣREE content of kaolinite veinlets and of the kaolinite concentrated by elutriation from an altered granitic rock at Haad Som Paen (Ranong) is 70 ppm and 75 ppm, respectively, thus enrichment of REE in kaolinite was not confirmed. In addition, by the sequential extraction experiments, 23% and 4% of REE were extracted from the altered granitic rock and the kaolinite veinlets at Haad Som Paen. In the altered granitic rocks at Haad Som Paen, REE are present as refractory phases, and REE in the acid‐soluble states had been leached by hydrothermal fluid.