Docstoc

Ore Prospecting Methods and Achievements in Yunnan

Document Sample
Ore Prospecting Methods and Achievements in Yunnan Powered By Docstoc
					       Ore Prospecting Methods and Achievements in Yunnan
                     By Mr. Li Wenchang, Chief Engineer
      Yunnan Bureau of Geology Mineral Resources Exploration & Development

Good morning, ladies and gentlemen,
It is my great pleasure to introduce some geological work made by Yunnan Bureau of Geology
Mineral Resources Exploration & Development in this conference.
1. A Survey of Yunnan Bureau of Geology Mineral Resources Exploration & Development
Yunnan Bureau of Geology Mineral Resources Exploration & Development (hereinafter “Yunnan
Bureau of Geology & Mineral Resources”) is a public institution under Yunnan provincial
government that undertakes basic, public geological survey, strategic mineral resources
exploration and geosciences study.
At present, the Bureau has 18,738 employees. Among 3,299 technicians, 453 of them have senior
technical titles and 1,322 have intermediate technical titles. Yunnan Geological Survey has been
established to undertake public geological survey while Yunnan Geology & Mineral Resources
Co., Ltd. has been established to undertake commercial geological exploration in accordance with
market demands.
In the past 40 years, the Bureau finished 1:200,000 regional survey that covers Yunnan by all
employees’ efforts, prospected a lot of large and ultra-large deposits such as Lanping Lead-Zinc
Mine, Xinping Dahongshan Iron Mine and Dongchuan Copper Mine. From 1990s, the Bureau
discovered and proved many a lot large and ultra-large deposits such as Zhenyuan Gold Mine,
Mengzi Bainiuchang Silver-Multimetals Mine and Lanping Baiyangping Silver-Multimetals Mine;
provided reserves of 145 tons of gold, 10,764 tons of silver, 4,500,000 tons of lead-zinc and
23,000,000 tons of pyrite. From 1996, with the implementation of “Three-River” special ore
prospecting plan, lots of large and ultra-large deposits has been discovered such as Deqin Yangla
Copper Mine, Shangrila Pulang Copper Mine, Lanping Baiyangping Copper-Multimetals Mine,
Simao Dapingzhang Copper-Multimetals Mine and Wenshan Bauxite Mine in important
mineralization belts, as well as provided reserves of 4,000,000 tons of copper, 172 tons of gold,
13,660,000 tons of lead-zinc, 10,758 tons of silver, 61,000 tons of tin and 15,050,000 tons of iron.
Yunnan part of “Three-River” area has been a new mineral resources base of nonferrous and
precious metals. At the same time, the Bureau developed many important geosciences projects
with other institutions and won first award of national science and technology development in
2005. All of these achievements will contribute to Yunnan’s economy development and the
construction of pillar industry—mining.
In recent years, the typical karst underground water survey, geological environment protection and
red-bed underground water exploration have met the water supply for 118,000 people, 54,400
livestock and 27280 mu of commercial crops which also have set an example for urban and rural
water projects.
The Bureau has cooperated with famous mining companies from Canada, Japan, Australia, UK
and South Africa on venture exploration. Over 50 venture exploration projects have been signed
that covered over 4,000 KM2 and over 100,000,000 RMB has been introduced from foreign
companies.
Vientiane potash deposit exploration has been finished made by the Bureau and Laos government


                                                 1
and now has been in testing development stage.
2. Geological Work and Ore Prospecting Methods in Yunnan
Geological work in Yunnan can be divided in to several stages according to working contents and
methods. Before 1970s, geological work in Yunnan is same as other provinces, mainly undertook
1:1,000,000 geological survey and map compilation. Some large and medium outcropping
deposits like ferrous, nonferrous metals and phosphorite were discovered. In this stage, routine
geophysical exploration methods developed rapidly. With the extensive application of airborne
magnetic survey and surface magnetic measurement, iron mines like Xinping Dahongshan large
hidden deposit was discovered. Meanwhile, magnetic measurement was effective in prospecting
copper-nickle and Pt-Pd deposits that is related to ultrabasic rocks. 1:1,000,000 and some
1:200,000 gravity survey contributed to the discovery and evaluation of a great deal of salt
deposits. Natural current method, mise-a-la-masse method, electrical profiling and electrical
sounding were extensively adopted in metal deposits exploration. In early 1970s, electrical method
was also extensively applied in underground water exploration. Radiogeophysical survey was
mainly used to find Uranium deposits. By 1:200,000 airborne radioactivity survey, some
radioactive anomalies were detected and surface radiogeophysical survey discovered Uranium
deposits. Downhole geophysical survey were applied in prospecting coal and salt deposits and
later broadly used in metal prospecting.
From 1980s to 1990s, great changes had taken place in ore prospecting methods and technology.
Expect the application and completion of geophysical survey, breakthrough of trace gold analysis
technology made geochemical survey effective in discovering gold deposits. 1:50,000 stream
sediment survey and 1:10,000 soil survey in abnormal area based on 1:200,000 stream sediment
geochemical survey, were successful pattern for gold prospecting in Yunnan. The above method
was used in circled ductile shear zone of Zhenyuan ultra-large gold mine that led to achievements
and fast evaluation. In this stage, electrical methods were greatly developed. For example, induced
polarization (IP) method was extensively applied in discovery and evaluation of metal deposits. In
late 1990s, because the range limitation of IP, transient electromagnetic method (TEM) was
introduced in the discovery and evaluation of hidden, rich lead-zinc and other massive sulfate
deposits.
After 2000, researches and practices have been done in ore prospecting methods and technology
of Yunnan. Remote sensing was adopted intensively for geological exploration. Based on the
interpretation of lineament and circular structure, alteration information interpretation was
developed. By aid of GIS, mineralization forecast can be done based on information of geology,
geophysics, geochemistry and remote sensing. We adopted Hyperspectral Remote Sensing in some
magmatic belts exploration. Mineral mapping is used to observe hydrous minerals, some sulfate
and carbonate.
Portable Infrared Mineral Analyser (PIMA) was applied to identify minerals, encircle alteration
zone and evaluate porphyry copper in association with polished thin section identification.
Besides IP and TEM, EH-4 was also used in the discovery and evaluation of hidden, rich lead-zinc
and other massive sulfate deposits. In ore prospecting, we also adopted integrated technologies
such as “porphyry model + HRS+ high precision magnetic measurement” and “mineralization
system + gravity survey + magnetic measurement + electrical survey”.
3. Successful Ore Prospecting Examples
3.1 Pulang Porphyry Copper Exploration – using “porphyry model + HRS+ high precision


                                                2
     magnetic measurement”, achieve rapid ore prospecting breakthrough
Pulang Copper Mine is an important porphyry copper and multimetal enrichment zone. In early
1970s, the Bureau evaluated two medium copper mine: Hongshan (skarn) and Xuejiping
(porphyry). Because most of outcropping rocks in this area are basic porphyrite, and the common
sense was that porphyrite is related not to copper but iron, people gave up copper exploration there.
Based on information from foreign porphyry copper and gold mines, the Bureau made a venture
exploration for porphyry copper-gold and encircled several copper mineralization bodies. But in
2001, venture exploration was quitted.
By comprehensive study, we believe that large porphyry copper deposit could be found in that
area: A. large scale porphyrite parental magma arose strong differentiation, which provided
conditions for acid porphyry; B. pan and K-silicate can be found in porphyrite/porphyry body,
proved that magma – fluid system was formed in late magma evolution; C. one of the three
confirmation holes revealed good porphyry copper which showed good copper potential.
Therefore, we believe a good potential despite of difficulties.
Porphyry copper deposit model is ripe, the ore body generally formed in alternation belts of
K-silicate or sericitolite. We adopted satellite hyperspectral remote sensing to confirm magma and
alternation belts, PIMA associated polished thin section identification mapping to confirm
alternation belts and magnetic measurement to confirm rock boundary.
In Pulang, 15 ore bodies were confirmed through 1:50,000 mineral geological survey and soil
geochemical survey.
For the most potential Pulang multiple rock body, through large scale lithofacies mapping, high
precision magnetic measurement, hyperspectral remote sensing and PIMA, facies of side quartz
diorite porphyrite, middle beschtauite and granodiorite, as well as belts of side hornfels + pan and
middle K-silicate + pyrite-sericitization. Hence, we focused on middle of the multiple rock body
where K-silicate and pyrite-sericitization was found.
By now, over 20,000 meters of drilling have finished in main ore body KT1 of Pulang Copper
Mine and the proved reserve of copper is over 4,000,000 tons. The area shows the potential of
ultra-large deposits.
3.2 Baoshan Hetaoping Copper-Lead-Zinc Multimetals Mine – Example of Hidden Deposit
Exploration adopting “Gravity Survey + Magnetic Measurement + Electrical Survey”
Baoshan Hetaoping is a multimetal mine containing copper, lead, zinc, silver, gold and iron. The
exploration is a successful example of mineralization forecasting by integrated information and
prospecting by “gravity survey + magnetic measurement + electrical survey”.
By further study and comprehensive analysis of information of geology, geophysics, geochemistry
and remote sensing, smaller deposits found should have internal relation that constitute a
skarn/hydrothermal multimetal mineralization system related to hidden rock body and controlled
by fault and fissure system while main ore body maybe hide in-depth. Confirmed from low gravity
and high magnetism showed by 1:500,000 gravity- magnetic surveys, in-depth hidden granite
body was proved (Fig. 1). Directed by this new conception, mineralization forecast was developed
which further confirmed a good potential of target area.
Later 1:50,000 geochemical soil survey, 1:100,000 gravity survey and fast 1:50,000 surface
magnetic scanning showed horseshoe anomalies along Hetaoping anticline; according local high
gravity and magnetism in low gravity background, we confirm that the mineralization is related to
granite body in anticline axis because beside the anomalies of Pb, Zn, Cu, Ag and Cd, other


                                                 3
anomalies of Au, Sb, As, Hg were found surrounding them. Large-scale laser and high precision
magnetic scannings were operated in circled hidden rock body discovered several electromagnetic
anomalies caused by in-depth skarn copper and other metals. In Jinchanghe, a thick rock body
in-depth 250-270m, striking 650m, thicking 130m and deeping NW was confirmed by signature
points and tangent.
In 2003, testing drilling operation conducted in magnetic anomaly showed hidden skarn
copper-iron body at 276m in-depth. Upper copper-gold main body was 45.1m in thickness with
the grade of Cu 1.42% and Au 0.5%; lower magnetite was 308m in thickness with the grade of Tfe
31.84%.
The experience of exploration in Hetaoping and Jinchanghe promoted achievements in the area.
New ore bodies has been discovered in Hetaoping, Dachangwa, Jinchanghe, Douya, Huangcaodi,
Maozhupeng,Xinchang, Caoshan and Shangchang. All of these show the potential of a large scale
mutimetals base in this area.
My introduction is over. Thank you.


图 1(Fig.1)核桃坪地区地质图及重力等值线图(Geological and Gravity Contour Map of

Hetaoping)

正等值线(positive contour)负等值线(negative contour)零等值线(zero contour)

 (Fig.2)
图2      云南核桃坪地区金厂河电磁异常体钻孔验证剖面图(Testing Drill Section Map of

Jinchanghe Electromagnetic Anomaly in Hetaoping, Yunnan)

△   Z 垂直测量异常(Vertical Survey Anomaly)

~据钻孔资料反演曲线(Inverse Curve from Drilling hole Data)

 1. 一次推测含矿磁性体(First Inferred Magnetic Ore Body)

 2. 钻孔控制铜矿体(二次推测含矿磁性体)Copper Body Controlled by Drilling hole

     (Second Inferred Magnetic Ore Body)

 3. 钻孔控制铁矿体(二次推测含矿磁性体)Iron Body Controlled by Drilling hole (Second

     Inferred Magnetic Ore Body)

 4. 推测花岗岩岩体(Inferred Granite Body)

 5. 钻孔及编号(Numbers of Drilling Hole)




                                              4

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:13
posted:3/24/2010
language:English
pages:4