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Abstract
The fault and fracture structure was developed extremely in Gejiu ore district, and they related to the ore forming and controlled the occurrence and scale of ore distribution. This paper mainly discussed the REE geochemical characteristics especially REE distribution pattern for fault tectonite occurring in fault zone of Gaosong orefield. The results showed that the REE distribution pattern of fault tectonite presented three types of rich Eu, negative and weak negative Eu. The factors had impact on REE content and distribution pattern including the fracture dynamic differentiation, as well as wall rock and granite. The REE characteristics had a good metallegenic implication, and the REE and Sn content within tectonic had significant correlation, so it could provide relevant information for prediction of concealed ore.
... The NW fracture set includes the Daqingdong, Heimashi, Camel, Axi Village, and Lina fractures. The NS fracture set is not developed within the ore field ( Figure 1) [28][29][30]. The formation of the hydrothermal ore deposit, which is associated with magmatichydrothermal fluids, was the result of fluids generated in the Earth's crust migrating from low-permeability to high-permeability zones via the fracture structure, which includes lineaments near the surface. ...
Remote sensing technology is widely used in the application of the extraction of lineaments in geological research. However, most of the current traditional lineament extraction methods are based on edge detection technology using a digital filter to extract the mitochondrial features in the image. These previously used algorithms are generally unable to extract the mitochondrial features in the shadow area on the mountain and the area parallel to the direction of the solar incident angle. In this paper, we have improved the STA algorithm (Line Segment Tracking method). The line segmentation and connection methods were firstly proposed, and then 32 search directions were set with one pixel as the center to find the best continuity direction of the lineament. A threshold was then set in this direction to determine whether it was a line element. Finally, line elements were connected into lineaments for further lineament interpretation. The lineament data from three different directions were collected in the Gaosong ore field in the Gejiu mining area, namely at the first place the traditional Canny algorithm, then the improved line segment tracking method, and finally the field measurement. The coefficients of the three-type lineament variations were compared by calculating the lineaments’ strength and their density attributes. It shows that the lineament variability extracted based on the improved line segment tracking method is closer to the measured lineament variability. The results show that the lineaments extracted by the improved algorithm are closer to the measured data. The improved algorithm has higher precision than the traditional Canny algorithm. More realistic and comprehensive lineaments can be attained by using the improved method to extract lineaments in the mining area, which is helpful to the study of the geology of the mining area and helps to construct a more accurate structure model to serve the needs of the mine production.
There have been few studies of the green nephrite from Kutcho, northern British Columbia, Canada. In this investigation, the petrology, mineralogy, geochemical characteristics, and the genesis of green nephrite from Kutcho were systematically studied through polarized light microscopy, backscattered electron analysis, electron probe microanalysis, and laser ablation inductively coupled plasma mass spectrometry. The results were compared with previously reported data to determine the geochemical characteristics of green nephrite in the world's main deposits. The results show that the Kutcho green nephrite mainly have a microfiber interlaced texture, the main mineral is tremolite-actinolite, and the minor minerals are diopside, chromite, chromium-rich grossular garnet, with small amounts of chlorite. The presence of chromite indicate that the host rock was ultramafic, while the chlorite indicate a low temperature of the ore-forming process. The Kutcho green nephrite is rich in Si⁴⁺ and Ca²⁺, and the Fe²⁺/(Mg²⁺+Fe²⁺) ratio is >0.06. The high Cr-Ni-Co value indicates that the Kutcho green nephrite is a serpentinite-related nephrite. Through the analysis of Ca²⁺/Mg²⁺ (>0.4) and the Sr/Ba, Zr/Hf, Nb/Ta, and Th/U ratios, it is inferred that the Kutcho green nephrite was formed in a relatively reducing acidic environment saturated with Ca²⁺. In an acidic environment, the ultrabasic or mafic rock was altered into serpentine, and tremolite-actinolite was formed under the repeated metasomatism of magma and hydrothermal fluid. The total rare earth element (∑REE) content of samples is low (2.1–2.9 ppm), the light/heavy REE ratio (LREE /HREE) is <1 (0.7–0.8), there is a loss of LREEs and enrichment of HREEs, δEu is a weak negative anomaly (0.7–1), and δCe is a strong negative anomaly (0.2–0.3). A comparison of the geochemical characteristics of green nephrite from different deposits show that the Mn (3797.8–5006.8 ppm) content and the ΣREEs value of Kutcho green nephrite are the highest among all the local deposits. Green nephrite from both the Kutcho and Polar mines has a low Al content.
Luziyuan Pb-Zn deposit is located in Zhenkang-Baoshan block, southern section of Sanjiang metallogenic belt. The ore bodies occur in a set of carbonate rock series of the ∈3s2, ∈3s3. They are bedded, lenticular and vein, strictly controlled by structure. A large number of skarn minerals are occur in ore bodies and their surroundings. The REE distribution patterns of marbles and ores are enriched LREE and apparent medium negative Eu anomaly and unobvious Ce anomaly. The REE distribution patterns of Skarn include weak negative Eu and unobvious Eu anomaly or inclined positive anomaly. The marble, skarn and ores have similar REE distribution patterns which are enriched LREE, and have apparent negative Eu and unobvious Ce anomaly. Through the analysis of REE characteristics of rock (ore), and in combination with deposit geological characteristics, suggests that the mineralization mainly occurs under the environment of relative reduction and its ore-forming materials are mainly sourced from the deep hydrotherm, and partly from the ore-hosting strata (∈3s2, ∈3s3). The research shows that the deposit hosted in the carbonate formation is a hydrothermal filling and metasomatic skarn-type Pb-Zn deposit obviously controlled by tectonics.
Nephrite genesis and its origin identification is an important branch in the research of petromineralogy and archaeology of ancient jade. Among the numerous studies conducted by predecessors, REE (rare earth element) was taken as a significant tool analyzing mineral genesis and geochemical conditions, and thought to be valuable in further research. This paper used measuring methods as LA-ICP-MS to analyze REE compositions of Hetian-Xinjiang, Liyang-Jiangsu, Luodian-Guizhou, and etc. Combined with data reported by predecessors, and applying statistical methods as variance analysis, the paper conducted a relative systematic analysis and comparison of REE contents, patterns and related parameters of nephrites from the above origins. The results showed that, due to the diversity in ore-forming fluids and geochemical settings, certain differences of REE contents and patterns among various origins existed: nephrites from Hetian-Xinjiang presented a strong negative anomaly of Eu; nephrites from Xiuyan-Liaoning displayed an obvious fractionation between LREE and HREE; nephrites from Ge'ermu-Qinghai had a relative low REE contents; nephrites from Liyang-Jiangsu, Luodian-Guizhou and Wenchuan-Sichuan had a common feature of negative Ce anomaly; and the above characteristics could be regarded as diagnostic features. Combined with REE differences among nephrites of different origins and their major elements as well other trace elements feature, the paper explored nephrite origin identification within China.
REE content of early Cretaceous intermediate-acidic volcanic-intrusive complex in Shanmen region, southeast Zhejiang province, China, was analyzed by ICP-MS, REE geochemistry characteristics of which was studied comparatively. The REE distribution patterns for various rock types in the area were consistent with the exception of Eu and exhibit right-dipping patterns with LREE enrichment, and the stable Sm/Nd, La/Nd, La/Sm ratio, indicated that they had the same magma source, with different degree of differentiation and evolution. Eu/Sm ratio(0.02 to 0.09 and 0.15 to 0.21)and the consistent Nb/Ta ratio(13.9 to 16.9) between the values of the crust and mantle, indicated that they were products of the crust-mantle magma mixing. The covariant relation of REE suggested that partial melting may be the principal diagenetic process. Combined with trace elements geochemistry, early Cretaceous Comagmatic activities of Shanmen region may be related to back-arc extensional tectonic setting caused by lithospheric extension after subduction and collision of the ancient Pacific plate.
Calcite is the dominant gangue mineral in the Furong tin-polymetallic deposit. The calcites associated with greisen type ore, altered rock type ore and skarn type ore from Bailashui and Goutouling mineral district, are characterized by two types of REE distribution patterns, LREE-enriched pattern and flat REE pattern. LREE-enriched pattern of calcites accompanying greisen type ore and skarn type ore are very similar to those of Qitianling granite. It implied that this REE behavior of calcite inherited from the characteristics of LREE-enriched magmatic hydrothermal fluid derived from the Qitianling granite plution. The calcites associated with altered rock type ore with flat REE distribution patterns indicate LREE of the hydrothermal fluid extracted during the alteration or mineralization process. Therefore, the data of calcites suggest a magmatic source for the or-forming hydrothermal fluid.