INTRODUCTION

The project, titled " Origin of gold ore fluids  in Dexing copper-gold district (China) " is a grant funded by Chinese National Science Foundation (grant # 40403006; ¥280,000; 1/2005-12/2007). The approval of the grant was resulted from a joint effort between Dr. Xiaofeng Li of the Institute of Mineral Resources of China National Academy of Geosciences, who now serves as a two-year term (11/2005-11/2007) visiting research fellowship at the National Institute for Geo-Resources and Environment, Tsukuba, Japan, and Dr. Chunzeng Wang of the University of Maine at Presque Isle. Drs. Li and Wang started their research collaboration several years ago and have jointly published four research papers on "Ore Geology Reviews", "Resource Geology", and "Mineral Deposits" by the summer of 2006.

The Chinese NSF-funded Dexing project covers several gold and copper deposits in Dexing mineral district, one of the largest copper-gold districts in China and located in the northeast of Jiangxi Province of south China. It is aimed to understand origins of ore-forming fluids and their relation to deformation processes. Several modern research and analytical methods and techniques, including microstrctural analysis, isotopic analysis of noble gases obtained from tiny pyrites and other stable isotopes such as sulfur and oxygen, Ar-Ar geochronology and SHRIUMP ion microprobe, etc., are used/applied in the research. Significant progress has been made toward a much better understanding of the mineralization processes.

2006 SUMMER FIELDWORK

The 2006 summer fieldwork in Dexing copper-gold district was successfully completed although I still have bad and horrible memories of the most unusually hot and muggy weather I experienced during my travel--it was over 100 degrees every day and over 90 degrees every night and it was so much humid that I always felt like in a sauna. The fieldwork and trips were financially supported by the above-mentioned Chinese NSF-funded grant and another small grant to me awarded from Chinese NSF's "Special Grants to Overseas Chinese Scholars for Short-term within-China Research and Lectures". The fieldwork focused on Jinshan gold deposit. We thank Jiangxi Provincial Department of Geological Survey and Mineral Exploration, Jinshan Gold Mining Co., Yinshan Silver-Lead-Zinc Mine, Dexing Copper Mine, and Yongping Copper Mine for their kind reception and fieldwork help. The following pictures were taken during the summer of 2006's fieldwork in Dexing copper-gold district. Enjoy.

Jinshan gold deposit, the largest one south of Yangzi River, in south China, was the first mine we visited. Jinshan in Chinese means "gold mountain". It is the name of the mountain where gold has been mined with only small operations for a long while, until early 1990's when geologists declared it a big gold deposit after several years of drilling and intensive exploration. Now it is a modern mine with large-scale operation.

The deposit is restricted within a regional ductile shear zone that was developed in Shuangqiao Group, a thick formation of Meso-proterozoic metasedimentary rocks. This type of gold deposit is named "ductile shear zone-type gold deposit". Gold ore presents as either assimilated and pyrite-rich "mylonite" or quartz veins.

Drilling continues in the vicinity of Jinshan gold mine. These are the abandoned rock cores recently drilled. They were abandoned because of no gold. (Bad management in drilling cores. )

A picture taken with my Chinese collaborator, Dr. Xiaofeng Li (left), and our excellent mine guide, Mr. Xiankui Yi, a geologist working for the provincial

Department of Mineral Exploration.

The Jinshan ductile shear zone and its product, mylonite, at a small open pit. The rusty color is due to chemical weathering (iron oxidization).

At the same open pit. With Mrs. Yi (left) and Xu (right). Mr. Xu is a mining geologist working for Jinshan Gold Mine.

Underground shaft.

Ore observation in the shaft.

The gold-bearing quartz veins, a typical type of gold ore within the ductile shear zone. The darker the veins are, the higher the gold grade is. Chinese coin (close to the size of a quarter) for scale.

Quartz veins are boudinaged to become boudins or lenses due to strong shearing deformation. Again, a Chinese coin for scale.

Yinshan  Mine, another huge multi-metal deposit for copper, gold, silver, lead, and zinc in Dexing ore district, was the second mine we visited. Yinshan in Chinese means "silver mountain". However, what we saw around the mine was not a mountain but a deep open pit as the following pictures show. The deposit has been known as a product of hydrothermal processes associated with volcanic and sub-volcanic activities. The detailed mineralization processes and their geochronology, however, remain debatable.  The following pictures show Yinshan open pit and features of its ores.

Inside the open pit of Yinshan Mine.

Discussion between my partner Dr. Xiaofeng Li and the Chief Geologist of the mine, by chunks of ores. Inside the open pit of Yinshan Mine.

The porphyry, a shallow intrusive felsic igneous rock with porphyritic texture.

The ore with sulfides of iron, copper, lead, and zinc.

Tongchang Copper Mine, the largest open pit copper mine in Dexing ore district, and also the largest one in China, was the third mine we visited. Tongchang in Chinese means "copper mine". It is true that it is a copper mine, and a super huge copper mine as it shows below. The open pit has a diameter of more than one mile. It is a typical porphyry copper deposit associated with shallow igneous and hydrothermal activities. Porphyry-type copper deposit is the major target of worldwide copper exploration for years. There are several huge ones discovered along Chilian Andes and in the west of the United States.

A corner of the open pit.

Me and the Chief Geologist of the mine.

A chalcopyrite and pyrite-rich vein.

Swarms of fine veins of sulfides.