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31.
S.M. Naqvi T. Hanumanth Rao R. Natrajan K. Satyanarayana V. Divakara Rao S.M. Hussain 《Precambrian Research》1977,4(4):361-386
The Chitradurga base metal sulfide deposit is associated with eugeosynclinal metabasalts (～ 2.5 b.y.) and banded pyritiferous cherts. The pre-tectonic character of the deposit and meta-volcanics is indicated by their deformational textures, structures and radioactive age data. The mineral assemblages of these ores are similar to the Zn-Cu type of massive sulfide deposits associated with Archean—Early Precambrian eugeosynclinal metavolcanics in other shield areas. The deposit has a rather high concentration of Co; microprobe data indicate that most of it is found as cobaltite and linnaeite and that it is inhomogenously distributed in these minerals. Very strong sympathetic correlation between Co and Cu, and the simultaneous increase of both of these elements with depth has been found. The geochemistry of the Chitradurga ores and metabasalts, especially their Zn:Cu:Pb and Pb:Zn ratios, suggests that the base metal sulfide content is probably genetically related to the basaltic flows. It appears that the Chitradurga deposit belongs to the ‘massive volcanogenic’ Cu-rich class of sulfide deposits. The metal content of the ores appears to have been supplied by rapidly degassing highly undifferentiated protomantle along with the basaltic magma. 相似文献
32.
Haider A. Khwaja Pravin P. Parekh Adil R. Khan Daniel L. Hershey Ronaq R. Naqvi Abdul Malik Khalid Khan 《洁净——土壤、空气、水》2009,37(7):544-554
The physical and chemical characterization of aerosols from three large cities, Karachi and Islamabad, Pakistan, and New York City (NYC), USA, was investigated. A scanning electron microscope equipped with an energy dispersive spectrometer (EDS) was used to determine particle morphology and elemental composition of the samples. A Bruker Spirit system in combination with a Sahara detector provided both computer controlled Automated Chemical Classification (ACC) and digital mapping features for analysis purposes. The use of these two features to characterize the elemental composition, particle size, and to determine specific classes or source types is described in this paper. Filters were analyzed for the following elements; Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr, Y, Zr, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Au, Hg, Tl, Pb, and U. The EDS work was qualitative not quantitative. Seven source types (mobile, cement, soil, steel mill, fossil fuel, sea salt and biological) contributed to particulate matter in the ambient air of both cities in Pakistan, whereas there were eight source types (diesel, road dust, automobile, iron, residual fuel oil, sea salt, ammonium sulfate and ammonium nitrate) for NYC. For all three urban centers, vehicular traffic emissions were the main contributor to particle number. Diesel emissions from trucks and buses were relatively more prominent in NYC aerosols, while gasoline emission from automotive exhaust was dominant in the two cities of Pakistan. The cement/limestone component from local cement industries was very evident in both particle surface characteristics and number for both Karachi and Islamabad, but not in NYC air. Sea salt aerosols were seen in the two coastal cities, Karachi and NYC. It was also witnessed in Islamabad aerosols and was attributable to the mining of rock salt at the world's richest salt mine, Khewra, situated upwind from the city. 相似文献