Petrogenesis of LREE-rich pegmatitic granite dykes in the central Grenville Province by partial melting of Paleoproterozoic-Archean metasedimentary rocks: Evidence from zircon U-Pb-Hf-O isotope and trace element analyses

Abstract

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Oxygen Fugacity and Volatile Content of Syntectonic Magmatism in the Neoarchean Abitibi Greenstone Belt, Superior Province, Canada

“…The chondrite normalized (CHUR) oxybarometer [69] uses the La content of zircon and seems to be the least reliable method, as results cross many buffers, and are uncorrelated with results obtained using other methods. The CHUR-method is strongly dependent on the quality of the La measurement and to La-increase induced by alteration and La-rich inclusions [56][57][58], as is observed in the studied zircons. This method is likely unreliable in hydrothermally altered contexts.…”

“…Prior to data processing, pristine and non-pristine zircons are identified using a preexisting method, proposed by Zeh and collaborators [56]; Turlin and collaborators [57]; and Groulier and collaborators [58]. The pristine and non-pristine grains are distinguished using CL and BSE imaging.…”

“…Preserved oscillatory zoning (Figure 5) and resorption in other grains, point to complex crystallization history. Altered zircons may be enriched in trace (e.g., Ca, P, Al, Fe, Sr, and Ti) elements compared to unaltered zircons [57,58,93]. Gain of trace elements may also be due to coupled substitution of non-formula elements [94,95] and to inclusions of feldspar, quartz or apatite [96][97][98].…”

“…In felsic and intermediate intrusions, the Ti-content of zircon is generally less than 20 ppm, which corresponds to average crystallization temperatures of 653 ± 124 • C and 758 ± 98 • C, respectively [99]. Alteration [95,97] or the entrapment of co-precipitated phases [57,58] may explain Ti enrichment (up to 150 ppm Ti), which lead to unreliable temperature estimates [100].…”

REE Enrichment during Magmatic–Hydrothermal Processes in Carbonatite-Related REE Deposits: A Case Study of the Weishan REE Deposit, China

“…Several studies have shown that magmatic processes can be responsible for high-grade REE mineralization, especially that hosted in pegmatitic granite [27,28]. However, recent studies of carbonatite-hosted REE deposits found that a second magmatic-hydrothermal process was required to form high-grade REE deposits [13,[29][30][31][32][33].…”