排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
This study considered the possibility of using visible and near infrared (VNIR) spectral absorption feature parameters (SAFPs) in predicting the concentration and mapping the distribution of heavy metals in sediments of the Takab area. In total, 60 sediment samples were collected along main streams draining from the mining districts and tailing sites, in order to measure the concentration of As, Co, V, Cu, Cr, Ni, Hg, Ti, Pb and Zn and the reflectance spectra (350–2500 nm). The quantitative relationship between SAFPs (Depth500nm, R610/500nm, R1344/778nm, Area500nm, Depth2200nm, Area2200nm, Asym2200nm) and geochemical data were assessed using stepwise multiple linear regression (SMLR) and enter multiple linear regression (EMLR) methods. The results showed a strong negative correlation between Ni and Cr with Area2200nm, a significant positive correlation between As and Asym2200nm, Ni and Co with Depth2200nm, as well as Co, V and total values with Depth500nm. The EMLR method eventuated in a significant prediction result for Ni, Cr, Co and As concentrations based on spectral parameters, whereas the prediction for Zn, V and total value was relatively weak. The spatial distribution pattern of geochemical data showed that mining activities, along with the natural weathering of base metal occurrences and rock units, has caused high concentrations of heavy metals in sediments of the Sarough River tributaries. 相似文献
2.
This research paper aims to delineate and recognize different gold mineralization stages based on surface lithogeochemical data using factor analysis and Spectrum-Area (S-A) modeling, as well as geological data in Arabshah sedimentary rock hosted epithermal gold deposit, NW Iran. Based on the factor analysis, Au and Mn were allocated to factor 2 (F2) and then classified by the S-A fractal modeling. In addition, Au and F2 values were transformed to spectrum data, which were categorized by the S-A log-log plots. Accordingly, the main mineralization phase contains Au and F2 (Au-Mn) values greater than 800 ppb and 0.3, respectively, and is associated with the occurrence of minerals such as pyrite, arsenian pyrite, realgar, orpiment and oxidized sulfides. The first phase of gold mineralization, where Au typically ranges between 80 and 350 ppb, is associated with base metal sulfides, arsenian pyrites and F2 values between 0.1 and 0.2. The second gold mineralization phase consists of Au values from 350 to 800 ppb and F2 values between 0.2 and 0.3. Combination of the S-A modeling, factor analysis and geological data outlined three gold mineralization stages in Arabshah gold deposit. The main mineralization stage showed a strong positive correlation with the NE-SW and NW-SE trending structures, the altered intrusive rocks such as microdiorite and granodiorite, and the altered subvolcanic dacitic domes. 相似文献
3.
Farahnaz Daliran 《Mineralium Deposita》2008,43(4):383-404
The disseminated gold deposit of Agdarreh (24.5 t at 3.7 g/t Au) is hosted in hydrothermally leached Miocene reefal limestone
in the Takab geothermal field, which is part of the Cenozoic Urumieh–Dokhtar volcanic arc of NW Iran. Alteration and mineralisation
are largely bedding controlled blanket-like and include: (1) pre-ore decalcification; (2) first-stage silicification associated
with pyrite (early pyrite with 3–4 wt% As, late pyrite with <1–3 wt% As) and sphalerite; (3) second-stage silicification with
precipitation of galena, Pb–Sb–As sulphides, sulphosalts, tellurides and native bismuth; (4) late-stage cinnabar and barite
in vugs; (5) oxide ore stage and carbonate alteration (complex Mn–Fe-rich oxyhydroxides, arsenates, sulphates, APS minerals
and rutile in residual leached rock and infill of karstic cavities). Gold occurs invisibly in the jasperoids and is enriched
in the Mn–Fe oxyhydroxide surface cap of the jasperoids. Gold mineralisation is associated with the hydrothermal metal suite
of As, Sb, Hg, Te, Se, Tl, Ba, Zn, Ag, Cd, Bi and Pb, and is characterised by very low Cu contents. Arsenian pyrite probably
carried most of the primary (invisible) gold. Native gold occurs in association with the late-stage cinnabar and the oxide
ore.
The Agdarreh deposit shows many similarities with Carlin-type ore and is interpreted to have resulted from near-surface hydrothermal
activity related to the Cenozoic arc volcanism that developed within the extensional Takab graben. The extensive oxidation
at Agdarreh may be partly due to the waning stages of hydrothermal activity. Active H2S-bearing thermal springs are locally depositing extremely high contents of Au and Ag, and travertine is present over large
areas, suggesting that ore-forming hydrothermal activity occurred periodically from the Miocene to Recent in the Takab geothermal
field.
The present paper deals with the geological framework, host rocks, characteristic features of hydrothermal alteration and
mineralisation, and genesis of the Agdarreh deposit. The results of fluid inclusion and stable isotope studies are in progress
and will be given in a forthcoming paper. 相似文献
1