Search

Indium (In) is a critical metal in liquid-crystal displays and solar panels. The Earth's crust has low In concentration in the order of 10 ng g−1, but it may be concentrated in sulphides by up to six orders of magnitude. Although In isotope studies may improve our understanding of the behaviour of In during different geological processes, such studies are limited for terrestrial samples. Here, we report a new method for In purification and high-precision isotope analysis for chemically different standards. A one-column method was used to separate In from the matrix with a recovery of 98% ± 2% (2SD). Indium concentrations and isotopic compositions were determined using the column eluate, and the results show large In isotope fractionation on desorbing In from the resin. Based on the mass balance, no significant In isotope fractionation was observed when In recovery is >93.8%. In terms of precision and accuracy of In isotopic compositions, the Ag-doping method was likely better than the standard–sample bracketing (SSB) method for correction of instrumental fractionation, with In uptake concentration down to 1 ng g−1 during isotope analysis. To ensure the accuracy of isotope analyses, the concentration match between the sample and standard should be within ±30%. An elemental doping study indicated that Na, K, Te, Sb, Pb, and Cu have no impact on the accuracy of In isotope analysis within the designated range; however, Ca/In, Mg/In, Cd/In and Sn/In ratios of >5, >20, >0.001 and >0.1, respectively, in sample solutions have significant impacts on In isotope analyses. Four international standards (BCR-2 basalt; J-Zn-1 sulphide; NIST-2711a soil; and OU-3 granite) and three in-house igneous rocks, purified using the developed method, had negligible isobaric interferences and matrix effect during In isotope analysis, demonstrating that the method can be used for terrestrial samples with different compositions. [ABSTRACT FROM AUTHOR]

Presents a study on the kinetic modeling of diagenesis of Eogene Lacustrine sandstone reservoirs in the Jianghan Basin, Southeastern China. Diagenetic features identified in the sandstones; Simulation of the kinetics of fluid-mineral reactions and the concentrations of aqueous species; Result of the weak pore fluid during the early diagenetic stage; Cause of the precipitation of quartz, kaolinite and illite.

The Malani Igneous Suite (MIS) in NW India represents one of the largest and well‐preserved Precambrian felsic igneous provinces, with minor mafic volcanics and dykes. The SIMS (Secondary Ion Mass Spectrometric) zircon U‐Pb geochronology yielded 776.8 ± 4.5 to 758.5 ± 6.9 Ma ages for rhyolites from Jodhpur region and Sindreth Basin while dacite sample from Punagarh Basin was dated to 760.5 ± 10 Ma. Zircons from rhyolitic and dacitic lavas have oxygen isotopic compositions that can be grouped into low δ18OV‐SMOW (4.12 to ‐1.11‰) and high (δ18O = 8.23‐5.12‰) categoroes, respectively. The low δ18O zircons have highly radiogenic Hf isotopic compositions (εHf(t)= +13.0 to +3.6) suggesting high temperature bulk cannibalization of upper level juvenile crust as the essential process for magma generation. Older than 800 Ma xenocrystic zircons in dacite have high δ18O values whereas 795 Ma ones have mantle‐like Hf‐O isotopic compositions, reflecting a significant shift in tectono‐thermal regime in NW India during 800‐780 Ma. A synchronous transition in the South China Block and Madagascar suggests a spatially and temporally linked geodynamic system. Geochemical data in combination with the new isotopic results point towards an overall convergent plate margin setting undergoing localized lithospheric extension. The NW India and South China blocks together with Madagascar and the Seychelles lay either along the periphery of Rodinia or off the supercontinent with the age of convergent plate margin magmatism coinciding with breakup of the supercontinent. [ABSTRACT FROM AUTHOR]