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Minerals 2016, 6(2), 45; https://doi.org/10.3390/min6020045

Clay Mineralogy of Coal-Hosted Nb-Zr-REE-Ga Mineralized Beds from Late Permian Strata, Eastern Yunnan, SW China: Implications for Paleotemperature and Origin of the Micro-Quartz

1,†
,
1,2,* , 3,†
and
1,†
1
College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
2
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, China
3
School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
These authors contributed equally to this work.
*
Author to whom correspondence should be addressed.
Academic Editor: Dimitrina Dimitrova
Received: 24 January 2016 / Revised: 17 March 2016 / Accepted: 11 May 2016 / Published: 17 May 2016
(This article belongs to the Special Issue Minerals in Coal)
View Full-Text   |   Download PDF [4191 KB, uploaded 17 May 2016]   |  

Abstract

The clay mineralogy of pyroclastic Nb(Ta)-Zr(Hf)-REE-Ga mineralization in Late Permian coal-bearing strata from eastern Yunnan Province; southwest China was investigated in this study. Samples from XW and LK drill holes in this area were analyzed using XRD (X-ray diffraction) and SEM (scanning electronic microscope). Results show that clay minerals in the Nb-Zr-REE-Ga mineralized samples are composed of mixed layer illite/smectite (I/S); kaolinite and berthierine. I/S is the major component among the clay assemblages. The source volcanic ashes controlled the modes of occurrence of the clay minerals. Volcanic ash-originated kaolinite and berthierine occur as vermicular and angular particles, respectively. I/S is confined to the matrix and is derived from illitization of smectite which was derived from the original volcanic ashes. Other types of clay minerals including I/S and berthierine precipitated from hydrothermal solutions were found within plant cells; and coexisting with angular berthierine and vermicular kaolinite. Inferred from the fact that most of the I/S is R1 ordered with one case of the R3 I/S; the paleo-diagenetic temperature could be up to 180 °C but mostly 100–160 °C. The micro-crystalline quartz grains (<10 µm) closely associated with I/S were observed under SEM and were most likely the product of desiliconization during illitization of smectite. View Full-Text
Keywords: coal-hosted Nb-Zr-REE-Ga mineralization; clay minerals; paleotemperature; microcrystalline quartz coal-hosted Nb-Zr-REE-Ga mineralization; clay minerals; paleotemperature; microcrystalline quartz
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Zhao, L.; Dai, S.; Graham, I.T.; Wang, P. Clay Mineralogy of Coal-Hosted Nb-Zr-REE-Ga Mineralized Beds from Late Permian Strata, Eastern Yunnan, SW China: Implications for Paleotemperature and Origin of the Micro-Quartz. Minerals 2016, 6, 45.

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