Rethinking the Prospecting Work and Direction of Hunan Diamond Primary Minerals
CHANGZHOU ANTALYA TOOL AND MACHINERY CO., LTD. , https://www.atly-tool.com
Key words: Hunan native ore diamond, potassium, magnesium, porphyry, prospecting area
I. The main work and major achievements of Hunan Diamond Prospecting
Hunan's diamond prospecting work began in April 1954 and has been more than half a century. The prospecting work has gone through the exploration stage of the diamond sand ore exploration stage (1954-1964), the first round of the original diamond mining census stage (1964-1984), the Sino-foreign cooperation and the combination of scientific research and production. (From 1985 to the present, it can be regarded as the second round of the original diamond diamond survey) and other three stages. The working area is 721 square kilometers, the sand ore dressing point is 139, the primary mine survey area is 66, and the discovery of the diamond sand mine area is 4 [1]. The main results achieved summarize the following aspects.
(1) After 4 years of census exploration, in March 1958, the final report of the geological exploration of the diamond sand deposit in the Dingjiagang mining area of ​​Changde County, Hunan Province and the Taoyuan mining area in Taoyuan County was submitted. The proven reserves of diamonds were 614,000 carats, which filled the country. A blank of diamond reserves. In 1959, the state built China's first diamond mine, the 601 mine. After arduous census work, two sand mine bases in Shenling Yaotou and Xiangyang Anjiang area were found in 1964, and the sand mine exploration report and the supplementary exploration report of the Ding, Tao mining area terrace and small fine grain sand mine were submitted respectively. At this point, the four sand mining areas in Shenshui have a total of 743,000 carats of proven diamond reserves, and have achieved remarkable results in prospecting. In April 1970, China's first artificial earth satellite was successfully launched, and the diamond used was produced in the submerged watershed.
(2) In the first round of diamond primary mine survey, through the analysis and research on the regional diamond mineralization geological conditions and the characteristics of diamond and its indicated minerals, and the anatomical evaluation of the anomalous area with diamond and its indicated minerals. Work reveals the multi-source and multi-period of diamond source in Shenjiang sand mine.
(3) Using the new theory of diamond mineralization at home and abroad, new methods and new methods of prospecting, in 1990, the first diamond-bearing olive-potassium-magnesium lamprophyre (group) associated with the veins was found in the Yunyingwo area of ​​Ningxiang. The original diamond prospecting work opened up a new situation.
(4) After the project of “Yangtti Platform Diamond Prospecting Research and Abnormality Verification†was launched, in 2007, one particle diamond was found in the 07NRzol sample of suspected (super) basic rock mass in Wangcheng Matian, which was the prospecting work of Hunan native diamond. Infused with new vitality.
Second, Hunan diamond primary ore metallogenic geological background
Hunan has the geological conditions for the formation of diamond host rocks, and has confirmed the presence of diamond-bearing host rocks. Therefore, the existence of native diamond mines with industrial value in Hunan should be unquestionable. In summary, there are mainly the following aspects (Fig. 1) [2].
1. Hunan has a relatively stable ancient crystalline base. A large part of Hunan (the upper Yangtze platform pleat belt - Wuling Mountain Area and Jiangnan Tailong Yi Xuefeng Mountain Area) is the edge activity zone of the Yangtze (quasi) platform, which belongs to the P-type craton, which is basically the same as the diamond-rich Western Australia quasi-platform. Similar, it is conducive to the formation of potassium-magnesium lamprophyre-type diamond primary ore.
2. Hunan has the thickness of the lithosphere required to form diamonds. According to deep geophysical data, most of the western and western parts of Hunan, the thickness of the modern or ancient lithosphere is between 150 and 300 kilometers, and in Changde Yitaoyuan, Dayong (Zhangjiajie), and Wuyuan and Shaoyang III. The region has formed a thickened area of ​​the lithosphere (250-300km), indicating that the upper and lower areas of the area are in a relatively stable state. This kind of rock ring with high stability, strong rigidity and large thickness is beneficial to the formation, growth and collection of slow medium diamond.
3. Hunan lithospheric fault development. The area has north-south eastward Exiangyu, Xianggui, Beidongcheng step-Taojiang (an ancient subduction collision zone), belly to Anren-Changde (conversion fracture), and east-west Xiangxiangyu and other five lithospheres. It intersects with the crust or basement, and is distributed in the group of slow-source-based ultrabasic rocks, volcanic and lamprophyre, and even potassium-magnesium lamprophyre. Ningxiang Yunyingwo, Yiyang Mujiang l Changde Port II, Huitong Ruoshui, Qiongban, Hongbamen and other places have discovered the micro-diamond-bearing potassium-magnesium lamprophyre, potassium-magnesium lamprophyre The potassium-magnesium lamprophyre volcanic shale-tuff, and the suspected ultra-basic igneous rock with micro-diamonds in Wangcheng Matian are sufficient to confirm that the geotectonic environment of this area is favorable for the formation of potassium-magnesium lamprophyre.
4. There are a large number of diamonds and indicator minerals unearthed in Hunan, and they are characterized by multiple sources and their own unique types. Hunan's Gangshi is mainly Ia type, accounting for 78.74%, IIa type only accounts for 12.85%, and no type IIb is found; Guizhou Maping mining area is mainly type IIa, accounting for 87.22%, Ia type is only 11.37%, nb Type accounts for 0.7%. There are significant differences between the two. Hunan's diamonds, its inclusion minerals P and E, are equally divided into autumn colors, and have a unique mixed (P+E) inclusion combination. This diamond in Hunan should have its own source.
Third, Hunan Jingang Extension Yuanyuan mine prospecting existence: problems and work difficulty
Finding a native diamond mine is a difficult and exploratory geological prospecting work that is recognized by the world's mining industry. But so far, the original diamond prospecting work in the lake library has not made a major breakthrough. In the end, it is really worthwhile to think about what is difficult and where there are problems in the work.
1. Technology updates are lagging behind in terms of prospecting deployment.
Before the end of the 1970s, diamond geologists all over the world agreed that kimberlite is the only parent rock of diamond, and its main indicator mineral is chrome-magnesium-aluminum garnet. After the discovery of a new type of primary diamond deposit of potassium-magnesium lamprophyre in the Argyll region of Australia, chrome spinel has been valued as an indicator mineral. With the advancement of science and technology, the new theory of diamond mineralization, new prospecting techniques and new methods were applied to prospecting in China after 1984, while the diamond primary minerals in Hunan (mainly in Changde and Jingzhou) were found. Most of the mining work was carried out before 1974. Therefore, only the kimberlite-type diamond primary ore is sought, but the search for the potassium-magnesium lamprophyre-type primary ore is neglected, and even the understanding of the potassium-magnesium lamprophyre-type primary ore is lacking. From this, it can be considered that the exploration and research work in many areas of Hunan's previous diamond primary ore prospecting work is still relatively low.
2. In the past, the method of prospecting was relatively simple. Using the classical heavy sand measurement method, although many diamonds and their indicated mineral anomalies (points) were found in the water system, the geophysical and geochemical methods were not well matched. In particular, the mineral identification method did not pass, and the chrome spinel in the sample was not identified and studied in detail. The new electronic probe technology was applied to mineral chemical composition testing in 1984. Therefore, the large number of magnesia-alumina and chrome spinel obtained in the region before the 1970s have not been ascertained. After 1984, a small number of heavy sand samples were re-examined in the area, and some magnesium-aluminum garnets (most of which were burned out in comparison with standard magnesium garnet) were selected, and a small amount of electron probe analysis was performed on chrome spinel. The number of analyses is limited, and it is difficult to accurately and comprehensively explain the problem. It can be considered that the degree of research on diamond indicating minerals in the region is relatively low.
3. In the past, the work thoughts paid more attention to the upward selection of the distribution and sorting rules of diamond and its indicated minerals in the heavy sands of the mainstream water system in Shenjiang, while neglecting the research and exploration of the characteristics of near-source and lateral recharge. The geological work of the four diamond sand mining areas in Changde Dingjiagang, Taoyuan City, Taoling Kiln, Hongjiang Anjiang and the margins of the Red Plate in the Mesozoic and Cenozoic areas are very low. The deployment of prospecting work in the near future is relatively large.
4. The vegetation in the area is developed, the red earth weathering shell is thick, the artificially reconstructed landform is severe, the rice fields are widely distributed, and the kimberlite/potassium-magnesium lamprophyre is weak in weathering resistance. The target rock mass may have been strongly weathered into red (yellow, blue). The soil has been completely unrecognizable. Some of the rock masses (especially rock pipes) are likely to be covered by the Quaternary and even produced in negative terrain. This undoubtedly increases the difficulty of prospecting. In addition, in the previous prospecting, only the plaque structure of kimberlite/potassium-magnesium lamprophyre was emphasized, and its debris structure was not taken seriously. Geological observations have not been able to effectively identify rock masses, or because of the guidance of the upward cable source, and the failure to take effective measures to actively find, delineate and expose the covered rock mass produced by negative terrain should also exist.
In summary, Hunan's previous diamond primary ore exploration and research work, although the experience of a long time, the amount of input work is also a lot, but the degree of exploration and research is still relatively low, there are more problems, the difficulty of work It is also larger than domestic and many other parts of the world. According to the geotectonic background, metallogenic geological conditions, diamond sand deposits and diamonds and their indicated mineral distribution in the region, it is necessary to further strengthen the research and evaluation of Hunan native diamond mines.
Fourth, the exploration of ore prospecting methods, ideas and directions
1. Hunan has a vision to find a native diamond deposit
At present, four small and medium-sized diamond sand mining areas in Changde Dingjiagang, Taoyuan, Shenling Yaotou and Xiangyang Anjiang have been discovered in the Hunan area of ​​the Yangtze platform. According to statistics and analysis data, the above-mentioned diamonds in each mining area have their own different characteristics, and the characteristics and distribution characteristics of diamonds and their indicated minerals in the area show the characteristics of near-source replenishment and lateral recharge. The multi-source multi-phase of its source. The diamond particles in the area are large and of good quality. In the past, it was found that there were nearly 200 diamonds larger than 100 mg (0.5 carats) and the largest weight was 70 carats. According to incomplete statistics of the previous sand mine exploration in the Chenxi-Huangxikou section and the recent mining data, hundreds of diamonds larger than 10 carats have been found in this section. It is further explained that there are large and rich diamond primary deposits in the area.
The 413 team of the Hunan Provincial Geological Prospecting Bureau conducted a secondary development and comprehensive study on the past data, and based on the following five factors, the Hunan diamond primary ore prospecting area was divided:
(l) The base age is 1800-2500 Ma (P type) craton;
(2) The super lithospheric fault zone or lithospheric fault zone intersects with the crustal fracture or basement fault;
(3) Areas with a lithospheric thickness greater than 150 km;
(4) Basic, ultrabasic and lamprophyll (group) with or without diamond;
(5) There is a distribution of diamond sand or diamond and its indicated mineral anomaly (point).
A total of five prospecting areas of Taoyuan, Changde, Shimen, Hongjiang, Yipu, Fenghuang, Lijiang, and Jingzhou, and Ningxiang and Taojiang were identified. According to the target selection principle determined by the research, more than 20 key target areas including Shimen Shangwutong were selected in the prospect area. The comprehensive factors show that through further analysis and exploration of these key target areas, it is very possible to achieve the goal of finding diamond primary deposits in Hunan as soon as possible.
2. Suggestions
(l) A large number of exploration and research work have confirmed that Hunan has formed a number of diamonds and their relative enrichment areas of indicator minerals, and it has been found that many of the diamond and its indicator minerals have surface features of near-source indication, especially through Studies on chromite or volcanic microspheres have been found to have near-indicative significance. Therefore, Hunan native diamond prospecting work should highlight the indication role of diamond itself. The abnormalities formed in the tens of kilometers of the supply area of ​​the four diamond sand mining areas and other diamond and indicator minerals relative enrichment areas should be paid special attention to the anatomy. At the same time, it is necessary to strengthen the heavy sand in the existing sand mining area, the artificial heavy sand in the rock mass, the natural heavy sand in the water system and the indicator minerals (including chromite, magnesium aluminum garnet, magnesium aluminum, iron and aluminum with surface structural features). Contrasting research on garnet, chrome diopside, omphacite, forsterite, phlogopite and other minerals with high temperature, high pressure and deep source indications, obtaining as much information on rock mineralogy as possible and clarifying Source, replenishment or indicative relationship for better and faster diamond exploration and research.
(2) Hunan diamond primary ore prospecting used to use the water system heavy sand method and geological observation method along the riverside ditch source (similar to the gold found through sand gold), the integration of metallogenic geological background and diamond and its indicated minerals. The analysis and research are not enough, the direction and objectives are not very clear, and they are often far-reaching. The author believes that the modern water system heavy sand method may be effective for conducting diamond primary ore prospecting work in areas with single linear diffusion field characteristics. However, there are some factors influencing the distribution pattern of diamond indicating minerals. For example, the Quaternary coverage area, the diamond and its indicator minerals have been subjected to complex hydrodynamic effects, and their distribution has been characterized by complex surface diffusion field. Water system heavy sand method recovery may be powerless. Therefore, in some anomalous areas where diamonds and their indicated minerals are concentrated and the Quaternary is heavily covered, it is particularly important to use a variety of working methods, including physical and chemical means. On the basis of carrying out large-scale high-precision aeromagnetic survey and regional gravity survey, ground aerospace geochemical exploration and remote sensing survey work should be carried out in aeromagnetic anomaly area, gravity anomaly area and diamond indicating mineral anomaly area. For key anomalous areas (points), drills, wells, and trenching projects can be directly exposed and dissected, with a focus on points and breakthroughs.
(3) According to the characteristics of weak basic weathering and ultra-basic rock weathering resistance and the world's primary diamond prospecting experience, Hunan's original diamond search work should attach great importance to the circle structure of the supply source area or have a round shape. The exploration and evaluation of the negative terrain of the feature focuses on the search for the Renfu rock mass.
(4) Hunan diamond primary ore exploration work, in the direction of prospecting, should be placed in the northwest and northward slopes of the slow-moving Chengbu-Taojiang Yining Township Liuyang arc-shaped ancient subduction zone, by E Xiangyu, Xianggui The Xiaoxiangyu is developed in the area affected by the 2 Changde-An-Anli lithospheric fault and focuses on the Nitrogen Magnesia porphyry-type diamond primary ore (also pay attention to the new type of diamond-bearing rock mass other than kimberlite and bovine magnesia porphyry). Studies have shown that the word west begins to be craterized after the snow-capped movement, and the platform gradually becomes indefinite. The slow-growing diamond begins to form and grow (the diamond is in the middle of the ground) and needs to be 51 billion years. The Yinzhi-Yanshan land-building and fault-blocking movements benefited the deep faults of the original deep faults and continued to deepen and stretch, providing a good structural space for ore-bearing magmatism. The rutile and its indicator minerals were found in many places in the middle and the Cenozoic red beds in western Hunan. It has been shown that the Indosinian-Yanshan period is the main adult stage. Therefore, although Hunan diamond mineralization has multi-period, it should be the main direction of the diamond primary ore prospecting in the Yanshan-Yanshan period.
references
[l]Hang Xing, Gong Shouchun, etc. Report on the second round of ore prospecting area of ​​the original diamond mine in Hunan Province. Hunan Bureau of Geology and Mineral Resources, 1993/9
[2] Dong Bin, Chen Mingshan, Xiao Xianghui. The geological background of ore deposits in Hunan, and the prospecting direction of deposit geology, Vol. 25, 2006