نتایج جستجو برای: trace and rare earth elements
تعداد نتایج: 16915845 فیلتر نتایج به سال:
Definitions and characteristics The rare earth elements (REE) (sometimes referred to as the rare earth metals) are a group of 17 chemically similar metallic elements, including the 15 lanthanides, scandium and yttrium. The lanthanides are elements spanning atomic numbers 57 (lanthanum, La) to 71 (lutetium, Lu) (Table 1). The lanthanides all occur in nature, although promethium, the rarest, only...
this study aims to investigate and optimize the effects of the main parameters including the particle size, gravity and magnetic separation combination, high gradient magnetic separation, magnetic field intensity, shaking table slope, washing water flow, and electrostatic separation upon the rare earth element (ree) recoveries from iron mine waste. the electron microprobe showed that high amoun...
One of the most prominent cases of the study of alteration processes and their effect on geochemistry is the ophiolite investigation. The Marivan-Palangan ophiolite (MPO) complex is a part of the Neotethyan ophiolites, which situated in the Kurdistan Province, western Iran. The studied samples reveal the occurrence of the secondary minerals such as epidote group, chlorite, zeolites, and less ca...
Y. Weiss, R. Kessel, W. L. Griffin, I. Kiflawi, D. R. Bell, J. W. Harris and O. Navon Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Macquarie University, NSW, Australia School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA Division of Earth Sciences, Unive...
A compilation of geochemical data from >50 active volcanoes where seismically defi ned Moho depth measurements are available, representing most volcanic arcs around the world, indicates a relation exists between crustal thickness (Moho depth) and the trace element composition of basalts. The best correlation exists for maximum light/heavy rare earth element (REE) ratios, and we use maximum Ce/Y...
The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare ea...
Ten international laboratories participated in an inter-laboratory comparison of a fossil bone composite with the objective of producing a matrix and structure-matched reference material for studies of the bio-mineralization of ancient fossil bone. We report the major and trace element compositions of the fossil bone composite, using in-situ method as well as various wet chemical digestion tech...
Kimberlites from West Greenland have Hf–Nd isotope as well as major and trace element compositions that are similar to other Group I kimberlites, but that are distinctive in the spectrum of magmas sampled at Earth’s surface. The West Greenland kimberlites have eNdi that ranges from +1.6 to +3.1 and eHfi that ranges from 4.3 to +4.9. The samples exhibit ubiquitous negative DeHfi (deviation from ...
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