SEG 45 Final_qx4 - Society of Economic Geologists
SEG 45 Final_qx4 - Society of Economic Geologists
SEG 45 Final_qx4 - Society of Economic Geologists
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18 <strong>SEG</strong> NEWSLETTER No 55 • OCTOBER 2003<br />
... from 17<br />
Tectonics and Metallogeny in China: The IGCP Field Trip and Symposium (Continued)<br />
<strong>SEG</strong> NEWS<br />
belt <strong>of</strong> Devonian rocks. Controversy at<br />
both deposits included whether these<br />
were indeed VMS systems, or perhaps a<br />
manto-like and skarn deposit, respectively.<br />
However, as the trip moved to<br />
the northwest, continuing within the<br />
Devonian rocks, there was little doubt<br />
that the Ashele copper deposit was a<br />
significant VMS orebody hosted by<br />
mafic volcanic rocks. The deposit, discovered<br />
in 1984, contains 900,000 t Cu<br />
(@2.3% Cu) and 400,000 t Zn (@2.7%<br />
Zn), with significant gold and silver. A<br />
large underground mining operation<br />
should begin by next year at Ashele.<br />
Two orogenic gold deposits, Saidu<br />
and Duolanasayi) were also visited<br />
within the more western part <strong>of</strong> the<br />
southern Altay. These deposits <strong>of</strong> probable<br />
late Paleozoic age are presently each<br />
recognized as containing perhaps<br />
200,000 to 300,000 oz Au and are yielding<br />
a few thousand ounces <strong>of</strong> gold each<br />
year. However, additional resource<br />
potential may exist in the deposits and<br />
in surrounding areas. In fact, gold<br />
placer workings from the 1970s and<br />
1980s are found along many <strong>of</strong> the<br />
rivers in the southern Altay. From the<br />
southwestern Altay, a lengthy two-day<br />
journey across the western Junggar<br />
basin took most participants to the<br />
western Tianshan and a visit to the 50-t<br />
Au Axi gold deposit, the largest gold<br />
deposit in northwestern China and the<br />
8 th largest gold producer in China.<br />
These Early Carboniferous low-sulfidation<br />
epithermal veins and breccias have<br />
been yielding about 40,000 oz Au/year<br />
since mine start-up in 1995. Although<br />
not visited, smaller high sulfidation<br />
epithermal gold deposits are scattered<br />
elsewhere in this region.<br />
This field symposium was collectively<br />
recognized as a successful and productive<br />
program by all attendees, in large<br />
part due to the outstanding organization<br />
by Mao Jingwen from the Chinese<br />
Academy <strong>of</strong> Geological Sciences, many<br />
<strong>of</strong> Dr. Mao’s colleagues at the academy,<br />
and their collaborators from the<br />
Xinjiang Bureau <strong>of</strong> Geology,<br />
Exploration, and Development. Visits to<br />
outstanding geological exposures and<br />
ores in this frontier region <strong>of</strong> China,<br />
were mixed with wonderful cultural<br />
experiences that included dances with<br />
the colorful local Uighur people, sampling<br />
<strong>of</strong> the varied local cuisine and<br />
brands <strong>of</strong> Maotai, and a trip to Kanas<br />
National Park centered around China’s<br />
deepest glacial lake. Much <strong>of</strong> our present<br />
understanding <strong>of</strong> the economic<br />
geology <strong>of</strong> this prospective region is<br />
detailed in a new book published for<br />
the symposium on “Tectonic Evolution<br />
and Metallogeny <strong>of</strong> the Chinese Altay<br />
and Tianshan” (Mao, Goldfarb,<br />
Seltmann, Wang, Xiao, and Hart, eds.,<br />
2003, IAGOD Guidebook Series v. 10,<br />
282 p.). The book is available from CER-<br />
CAMS at the National History Museum<br />
in London (R.Seltmann@nhm.ac.uk).1<br />
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