查看更多>>摘要：By studying the light isotopic compositions of carbon,oxygen,and hydrogen,combined with previous research results on the ore-forming source of the deposit,the authors try to uncover its metallogenic origin.The δ18O and δ13C isotope signatures of dolomite samples vary between 10.2 and 13.0‰,and between-7.2 and-5.2‰,respectively,implying that the carbon derives from the upper mantle.δD and δ18O of quartz,biotite,and muscovite from different ore veins of the deposit vary between-82 and-59‰,and between 11.6 and 12.4‰,respectively,imply-ing that the metallogenic solutions are mainly magmatic.According to the relevant research results of many isotope geologists,the fractionation degree of hydrogen isotopes increases as the depth to the Earth's core increases,and the more differentiated the hydrogen isotopes are,the lower their values will be.In other words,mantle-derived solutions can have extremely low hydrogen isotope values.This means that the δD‰ value-134 of the pyrrhotite sample num-bered SD-34 in this article may indicate mantle-derived ore-forming fluid of the deposit.The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma.
查看更多>>摘要：The sandstones of the Late miocene-Pliocene Dibdibba Formation in the Najaf-Karbala Plateau and Basra were examined to determine their source rocks and origin.The rare earth elements(REE)and trace elements(Sc,Co,V,and Th)concentrations in these sandstones revealed that they likely derived from a single source.The steep light rare earth elements(LREE)and flat,heavy rare earth element(HREE)patterns,negative Eu anomaly,and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks.The average concentration of ΣREE is 93.5 ppm,which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale.The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source.The Th/Co,Th/Sc,La/Sc,La/Co,Eu/Eu*and(La/Lu)cn elemental ratios indicated that these Late Miocene-Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.
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