Scavenging and release of REE and HFSE by Na-metasomatism in magmatic-hydrothermal systems.

Exploitable or potentially exploitable deposits of critical metals, such as rare-earth (REE) and high-field-strength elements (HFSE), are commonly associated with alkaline or peralkaline igneous rocks. However, the origin, transport and concentration of these metals in peralkaline systems remains poorly understood. This study presents the results of a mineralogical and geochemical investigation of the Na-metasomatism of alkali amphiboles and clinopyroxenes from a barren peralkaline granite pluton in NE China, to assess the remobilization and redistribution of REE and HFSE during magmatic-hydrothermal evolution. Alkali amphiboles and aegirine-augites from the peralkaline granites show evolutionary trends from sodic-calcic to sodic compositions, with increasing REE and HFSE concentrations as a function of increasing Na-index [Na#, defined as molar Na/(Na+Ca) ratios]. The Na-amphiboles (i.e., arfvedsonite) and aegirine-augites can be subsequently altered, or breakdown, to form hydrothermal aegirine during late- or post-magmatic alteration. Representative compositions analyzed by in-situ LA-ICPMS show that the primary aegirine-augites have high and variable REE (2194-3627 ppm) and HFSE (4194-16,862 ppm) contents, suggesting that these critical metals can be scavenged by alkali amphiboles and aegirine-augites. Compared to the primary aegirine-augites, the presentative early replacement aegirine (Aeg-I, Na# = 0.91-0.94) has notably lower REE (1484-1972) and HFSE (4351-5621) contents. In contrast, the late hydrothermal aegirine (Aeg-II, Na# = 0.92-0.96) has significantly lower REE (317-456 ppm) and HFSE (6.44-72.2 ppm) contents. Given that the increasing Na# from aegirine-augites to hydrothermal aegirines likely resulted from Na-metasomatism, a scavenging-release model can explain the remobilization of REE and HFSE in peralkaline granitic systems. The scavenging and release of REE and HFSE by Na-metasomatism provides key insights into the genesis of globally significant REE and HFSE deposits. The high Na-index of the hydrothermal aegirine might be useful as a geochemical indicator in the exploration for these critical-metals.

EFFECT OF COLLA CORNUS CERVI COMBINED WITH LV-MEDIATED BMP7 TRANSFECTED BMSCs ON ANFH IN RATS.

In the present study, we investigated the combined effect of Colla Comus Cervi (CCC) and BMP7-overexpressing bone marrow-derived mesenchymal stem cells (BMSCs) on osteogenic induction and the treatment of avascular necrosis of the femoral head (ANFH). BMSCs were isolated from rats. BMP7-overexpressing BMSCs were generated by lentiviral-mediated gene transduction. Cell proliferation, alkaline phosphatase (ALP) activity, osteogenesis related gene expression, osteocalcin levels, and calcified nodules were quantified and compared between four groups: untreated controls, BMSCs cultured with CCC complex medium, BMP7-overexpressing BMSCs, and BMP7-overexpressing BMSCs cultured with CCC complex medium (CCC+BMP7). CCC+BMP7 BMSCs showed higher proliferation rate. ALP activity and osteaocalcin content were significantly increased in CCC+BMP7 BMSCs. The osteogenesis related genes, COLI, and integrin-α2, -α5, and -ß1, were expressed significantly higher in CCC+BMP7 BMSCs. The number of calcified nodules in the CCC+BMP7 group was significantly higher than that in other groups. For in vivo assays, ANFH was induced in rats, and BMSCs were injected into the femoral head of the lower left extremity. In rats with induced ANFH, general observation scores of the CCC+BMP7 injected group were significantly higher than the model group. X-ray and microscopic observations revealed that ANFH was significantly improved and femoral head cells gradually recovered in rats treated with CCC+BMP7 BMSCs. Our results suggest that CCC+BMP7 significantly promote the proliferation and osteogenic differentiation of BMSCs in vitm. CCC+BMP7 BMSCs promote the ability of repairing ANFH in rats, providing a new therapeutic paradigm for the treatment of ANFH.

Isotopic evidence for continental ice sheet in mid-latitude region in the supergreenhouse Early Cretaceous.

Cretaceous represents one of the hottest greenhouse periods in the Earth's history, but some recent studies suggest that small ice caps might be present in non-polar regions during certain periods in the Early Cretaceous. Here we report extremely negative δ(18)O values of -18.12‰ to -13.19‰ for early Aptian hydrothermal zircon from an A-type granite at Baerzhe in northeastern China. Given that A-type granite is anhydrous and that magmatic zircon of the Baerzhe granite has δ(18)O value close to mantle values, the extremely negative δ(18)O values for hydrothermal zircon are attributed to addition of meteoric water with extremely low δ(18)O, mostly likely transported by glaciers. Considering the paleoaltitude of the region, continental glaciation is suggested to occur in the early Aptian, indicating much larger temperature fluctuations than previously thought during the supergreenhouse Cretaceous. This may have impact on the evolution of major organism in the Jehol Group during this period.