Tetrad Effect Research Articles

Translation of in vitro cannabinoid 1 receptor agonist activity to in vivo pharmacodynamic endpoints

IntroductionBuilding an understanding of in vivo efficacy based on the evaluation of in vitro affinity or potency is critical in expediting early decision making in drug discovery and can significantly reduce the need for animal studies. The aim of the present study was to understand the translation of in vitro to in vivo endpoints for the cannabinoid receptor 1 (CB1). MethodsUsing a selection of CB1 agonists we describe an evaluation of in vitro to in vivo translation comparing in vitro receptor affinity or functional potency, using both cAMP and β-arrestin endpoints, to various in vivo CB1 agonist-associated endpoints. ResultsWe demonstrate that in vitro CB1 agonism significantly correlates with the CB1-induced cue in the drug discrimination model in vivo, but not with other purported CB1 agonist-mediated in vivo endpoints, including hypothermia and sedation. Thus, these data challenge common perceptions regarding CB1 agonist-induced tetrad effects in rodents. DiscussionThis work exemplifies how in vitro profiling of receptor affinity or potency can predict in vivo pharmacodynamic effects, using the CB1 as an example system. The translatability of in vitro activity to in vivo efficacy allows for the ability to rapidly contextualize off-target CB1 in vitro findings, allowing clear and rapid definition of the risk posed by such activity without the need for extensive animal studies. This has significant implications in terms of early decision making in drug discovery and reducing the use of animals in research, while also outlining a template for expanding the approach for additional targets.

Rare earth element geochemistry of altered pyroclastic rocks in the Hashtjin area of north-west Iran

AbstractThis study evaluates the rare earth element (REE) geochemistry in altered trachyandesitic ignimbrites, tuff and lava flows in the Hashtjin area by assessing chondrite-normalized REE patterns and Y/Ho geochemical ratios. Modifications in the REE patterns took place along altered fault zones that were affected by hypogene and supergene alterations. The precursor volcanic and pyroclastic rocks contain phenocrysts of plagioclase accompanied by augite, zircon, apatite and pyrite. Based on X-ray diffraction analysis, the main mineral assemblages of the altered units consist of kaolinite as the main clay mineral, SiO2 polymorphs (quartz and cristobalite) and anatase as a minor constituent. The chondrite-normalized REE patterns of argillic samples reveal fractionation of light REEs (LREEs) compared to heavy REEs (HREEs), together with a marked Eu anomaly and a weak W-type tetrad effect related to the weak non-charge radius control (CHARAC) behaviour of REEs and slightly higher Y/Ho and Zr/Hf ratios. The relationship between the Y/Ho and Zr/Hf ratios and recognizable T3 and T4 effects (tetrad effect) suggests that an increasing degree of water–rock interaction occurred during hypogene alteration processes by acidic hydrothermal fluids that were overprinted by supergene alteration. Water–rock interaction and adsorption by Mn-oxides and clay minerals are considered to have played important roles in determining the close to non-CHARAC behaviour of REEs during the argillic alteration of the pyroclastic rocks in the Hashtjin area.

Evolution of the Fluoride–Calcium Melt Composition According to Experimental Data and Fluorite Formation in Rhyolites

The paper reports the results of melting experiments on the fluorite-enriched rhyolites of the Nyalga Basin (Central Mongolia). The fluoride–calcium (F–Ca) melt was obtained in a wide range of P-T parameters (1250–750°С, 5.5–1 kbar). Fluoride–silicate liquid immiscibility was observed at F > 2.5 wt % and CaO > 5.3 wt % in the initial system. An increase of temperature and pressure was accompanied by a significant increase in the concentrations of REE, Y, Sr, P, Th, U, Nb, Co, Cu, Sn, Sb, and Mo in the F–Ca melt. The peculiarity of the DREE distribution coefficients between F–Ca and silicate melts can lead to the formation of M-type tetrad effects for the first, third, and fourth tetrads in the chondrite-normalized REE patterns of silicate melt. The F–Ca melt has existed up to subsolidus temperatures of the rhyolitic melt. None of the models of magmatic crystallization of fluorite in haplogranitic melts or subsolidus postmagmatic and hydrothermal fluoritization can explain the origin of fluorite-enriched rhyolites. It is suggested that these rocks were formed from magma containing the emulsion of rhyolitic and F–Ca melts. The fluoride–silicate liquid immiscibility resulted in the redistribution of trace elements (REE, Y, Sr, P, Zr, Hf, Ta, Nb, Sc, Li, Be, and Rb) between melts. The formation of rock matrix was accompanied by degassing of the rhyolitic melt. An effective viscosity of the magma (melts emulsion with fluid bubbles) is comparable with the viscosity of a liquid. The F–Ca melt was quenched into F–Ca phase consisting of submicron fluorite particles, while solidification of the rhyolitic melt and silicate glass devitrification resulted in the formation of quartz–sanidine symplectites. The F–Ca phase has the elevated contents of O, Sr, LREE, Y, Si, sometimes Sc, P, and Al. The isomorphous substitution of O2– → F– in the fluorite structure led to the formation of aggregates of oxygen-vacancy centers, which are responsible for the laser-induced luminescence of the F–Ca phase in the rhyolite matrix. The wide variations of the REE, Y, Sr, Th, Nb, Ta, Zr, and Hf contents in the F–Ca phase are related to its recrystallization under the effect of fluid, which was released during degassing of rhyolitic melt. The submicron-sized fluorite particles in the F–Ca phase during the interaction with fluid were gradually liberated from impurities (besides Sr) and transformed into larger crystalline segregations. It is suggested that the oxygenated F–Ca melt exists in a metastable supercooled state under oxidizing conditions during eruption of rhyolitic magma. This is inconsistent with previously obtained experimental data on crystallization of fluorite from CaF2- and H2O-saturated haplogranitic melts at < 950°С and 1–2 kbar. Using rhyolites as example, it is shown that fluorite and associated ore mineralization (monazite-group minerals, cerianite) were derived from F–Ca melt with elevated REE and Y contents. In many igneous rocks and magmatogenic ores, fluorite could be a product of transformation of the F–Ca melt.

Evidence for mixed contribution of mantle and lower and upper crust to the genesis of Jurassic I-type granites from Macao, SE China

Abstract Much controversy has occurred in the past few decades regarding the nature of the sources, the petrogenetic processes, and the tectonic regime(s) of the Jurassic magmatism within the Southeast China magmatic belt. This study aims to contribute to the discussion with mineral chemistry, and whole-rock element and Sr-Nd-Hf-Pb isotopic geochemical data from granitic rocks and microgranular mafic enclaves from Macao, where two discrete groups of I-type biotite granites have been identified (referred to as Macao Group I [MGI] and Macao Group II [MGII]). It is proposed that the granitic magmas were generated by partial melting of infracrustal medium- to high-K, basaltic Paleoproterozoic to Mesoproterozoic protoliths (Nd depleted mantle model age [TDM2] = 1.7–1.6 Ga and Hf TDM2 = 1.8–1.6 Ga), triggered by underplating of hot mantle-derived magmas in an extensional setting related to the foundering of a previously flat slab (paleo–Pacific plate) beneath the SE China continent. The main differences between the two groups of Macao granites are attributed to assimilation and fractional crystallization processes, during which upper-crustal Paleozoic metasediments were variably assimilated by MGI magmas. This is evidenced by an increase in initial 87Sr/86Sr ratios with degree of evolution, presence of metasedimentary enclaves, and high percentage of zircon xenocrysts with Paleozoic ages. In addition, other processes like late-stage fluid/melt interaction and magma mixing also left some imprints on granite compositions (rare earth element tetrad effect plus non–charge-and-radius-controlled behavior of trace elements and decoupling between different isotope systems, respectively). The distribution of isotopically distinct granites in SE China reflects the nature of the two Cathaysia crustal blocks juxtaposed along the Zhenghe-Dapu fault.

Mineralogy, isotope geochemistry and ore genesis of the miocene Cuonadong leucogranite-related Be-W-Sn skarn deposit in Southern Tibet

The Himalayan orogenic belt is characterized by widespread leucogranites, which are mostly peraluminous with less than 5% mafic minerals. Previous studies mainly focused on the petrological characteristic, genetic mechanism, magmatic evolution and tectonic significance of these leucogranites. However, recently, a skarn-type Be–W–Sn polymetallic deposit, which is spatially related to the Cuonadong leucogranites of the Himalayan leucogranites belt, was discovered. The orebodies occur in the inner and outer contact zones between the Cuonadong leucogranites and their surrounding marble. This study focuses on the the characteristics of the skarn mineral assemblages. The deposit shows a typical skarn mineral zonation, from inside to outside, including dark pyroxene-garnet skarn zone, red garnet zone, dark green amphibole-specularite zone, light-green vesuvianite-epidote ribbon, and vesuvianite-chlorite zone. Zircon U-Pb dating shows that the ore-related leucogranite was emplaced at ca. 18 Ma. Geochemically, the leucogranite has high SiO2, Al2O3, Na2O, K2O and low CaO contents belonging to peraluminous granite. The Cuonadong leucogranite is characterized by right-dipping chondrite-normalized REE patterns with distinct negative Eu anomalies. Importantly, all samples show Lanthanide tetrad effect on chondrite-normalized REE patterns, indicating significant melt-fluid interaction has occurred due to strong fractional crystallization. Additionally, the Cuonadong leucogranite is enriched in large ion lithophile elements (such as Rb) and relatively depleted in high field strength elements (such as Nb, Zr, Hf), suggesting a crustal source region. High F and B contents in the magma could have significantly increased the solubility of water in the magma, while the magmatic-hydrothermal solution enriched in F and B should have remarkably enhanced the metal-carrying capacity and increased the permeability of surrounding rocks, which in turn effectively facilitated water–rock reaction.

Composition and origin of Ti–Nb–Ta–Zr bearing minerals in the Abu Diab highly evolved granite from the Central Eastern Desert of Egypt

The central Eastern Desert (CED) of Egypt is well-known for its granite-related Nb–Ta mineralization. The garnet-bearing muscovite granite (GMG) of the Abu-Diab composite pluton in the CED consists mainly of quartz, K-feldspar (Or88–98), albite (An0-4) and muscovite, with accessory minerals including garnet, zircon, columbite, ilmenite, Ti-rich hematite, rutile, ilmenorutile, thorite, apatite, xenotime and chlorite. The GMG is weakly peraluminous and has low Nb/Ta (9.6–15.4) and Zr/Hf (16–31) with discernible REEs tetrad effect (TE1-3 = 1.11–1.35), typical of highly evolved granites. Zircon contains high concentrations of U and Th typical of late-magmatic zircon and similar to zircon type from highly evolved granite. The homogenous and weak zoned columbites are classified as manganocolumbite. The formation of Ta-rich rim in the columbite may indicate that later fluids were from the GMG granite itself at advanced fractionation into exsolving fluids, and not from an external source. Ilmenite is greatly enriched in MnO, which indicates the significant pyrophanite (up to 29 mol %) molecules in ilmenite through simple substitution of Mn for Fe2+ with increasing oxygen fugacity under magmatic-hydrothermal conditions. Xenotimes show low analytical totals, suggesting probably hydration during their post-magmatic alteration, while apatite is small-grained associated with tiny zircons, suggesting late-crystalized phases. During late magmatic differentiation stage, the interaction of granitic melt with F-rich late magmatic fluids could be resulted in the formation of Ti–Nb–Ta–Zr minerals. Overall, the Abu Diab GMG possesses mineralogical and geochemical features that make it a potential target for Ti–Nb–Ta–Zr minerals.

The tetrad effect in REE distribution patterns: A quantitative approach to genetic issues of argillic and propylitic alteration zones of epithermal Cu-Pb-Fe deposits related to andesitic magmatism (Khan Kandi District, NW Iran)

The impact of the tetrad effect on the accumulation of REE during base metal mineralization can be deduced from four segments of the normalized REE distribution patterns. Quantifying this effect in each part of the REE graph has proven to be a powerful tool when it comes to the investigation of the origin of ore deposits. In the current research, a mathematical method using a logarithmic scale has been designed to calculate each individual tetrad segment in the samples and tested for the alteration zone of the andesite-related epithermal base metal deposits in the Khan Kandi District, NW Iran. In contrast to previous approaches, the current method achieves a higher accuracy for normalized REE patterns of samples from the argillic and propylitic alteration zones of base metal deposits. Using the calculation technique presented here reveals that the values obtained for third and fourth tetrad effects follow different trends in argillic and propylitic samples. In conclusion, mineralizing fluids of low pH accountable for the development of argillic alterations are characterized by larger σ3 (third tetrad) values in fault zones. They decrease toward the margins of the fault zones where argillic alteration is predominant whereas in the propylitic alteration zones the trend is reversed. The tetrad effect in these alteration zones is controlled pH, temperature changes and the fluid-rock interaction, conducive to the decomposition of minerals in host and wall rocks. The behavior of geochemical pairs such as Y/Ho, Zr/Hf and Nb/Ta displays a non-CHARAC behavior highlighted by non-linear and parallel trends in the chondrite-normalized REE curves. The occurrence of conjugate convex and concave tetrad effects in the REE patterns are accounted for by the mixing of meteoric waters and hydrothermal fluids. The correlation between σ3 values and geochemical couples are indicative of a mineralogy that formed under a regime of strong fluid-rock interaction. The data obtained from samples in the central parts of the fault zones document this zone as the pathways for hydrothermal solutions.

Different receptor mechanisms underlying phytocannabinoid- versus synthetic cannabinoid-induced tetrad effects: Opposite roles of CB1 /CB2 versus GPR55 receptors.

Cannabis or cannabinoids produce characteristic tetrad effects-analgesia, hypothermia, catalepsy and suppressed locomotion, which are believed to be mediated by the activation of cannabinoid CB1 receptors. Given recent findings of CB2 and GPR55 receptors in the brain, we examined whether these receptors are also involved in cannabinoid action. We compared Δ9 -tetrahydrocannabinol (Δ9 -THC)-, WIN55212-2-, or XLR11-induced tetrad effects between wild-type (WT) and each genotype of CB1 -, CB2 - or GPR55-knockout (KO) mice and then observed the effects of antagonists of these receptors on these tetrad effects in WT mice. Systemic administration of Δ9 -THC, WIN55212-2 or XLR11 produced dose-dependent tetrad effects in WT mice. Genetic deletion or pharmacological blockade of CB1 receptors abolished the tetrad effects produced by all three cannabinoids. Unexpectedly, genetic deletion of CB2 receptor abolished analgesia and catalepsy produced by Δ9 -THC or WIN55212-2, but not by XLR11. Microinjections of Δ9 -THC into the lateral ventricles also produced tetrad effects in WT, but not in CB1 -KO mice. CB2 -KO mice displayed a reduction in intraventricular Δ9 -THC-induced analgesia and catalepsy. In contrast to CB1 and CB2 receptors, genetic deletion of GPR55 receptors caused enhanced responses to Δ9 -THC or WIN55212-2. Antagonisim of CB1 , CB2 or GPR55 receptors produced alterations similar to those observed in each genotype mouse line. These findings suggest that in addition to CB1 , both CB2 and GPR55 receptors are also involved in some pharmacological effects produced by cannabinoids. CB1 /CB2 , in contrast to GPR55, receptors appears to play opposite roles in cannabinoid action.

A Late Cretaceous felsic magmatic suite from the Tengchong Block, western Yunnan: integrated geochemical and isotopic investigation and implications for Sn mineralization

AbstractThe Tengchong Block within the Sanjiang Tethys belt in the southeastern part of the Tibetan plateau experienced a widespread intrusion of a felsic magmatic suite of granites in its central domain during Late Cretaceous times. Here, we investigate the Guyong and Xiaolonghe plutons from this suite in terms of their petrological, geochemical, and Sr–Nd, zircon U–Pb and Lu–Hf–O isotopic features to gain insights into the evolution of the Neo-Tethys. The Guyong pluton (76 Ma) is composed of metaluminous monzogranites, and the Xiaolonghe pluton (76 Ma) is composed of metaluminous to peraluminous medium- and fine-grained syenogranite. A systematic decrease in Eu, Ba, Sr, P and Ti concentrations; a decrease in Zr/Hf and LREE/HREE ratios; and an increase in the Rb/Ba and Ta/Nb ratios from the Guyong to Xiaolonghe plutons suggest fractional crystallization of biotite, plagioclase, K-feldspar, apatite, ilmenite and titanite. They also show the characteristics of I-type granites. The negative zircon εHf(t) isotopic values (−10.04 to −5.22) and high δ18O values (6.69 to 8.58 ‰) and the negative whole-rock εNd(t) isotopic values (−9.7 to −10.1) and high initial 87Sr/86Sr ratios (0.7098–0.7099) of the Guyong monzogranite suggest that these rocks were generated by partial melting of the Precambrian basement without mantle input. The zircon εHf(t) isotopic values (−10.63 to −3.04) and δ18O values (6.54 to 8.69 ‰) of the Xiaolonghe syenogranite are similar to the features of the Guyong monzogranite, and this similarity suggests a cogenetic nature and magma derivation from the lower crust that is composed of both metasedimentary and meta-igneous rocks. The Xiaolonghe fine-grained syenogranite shows an obvious rare earth element tetrad effect and lower Nb/Ta ratios, which indicate its productive nature with respect to ore formation. In fact, we discuss that the Sn mineralization in the region was possible due to Sn being scavenged from these rocks by exsolved hydrothermal fluids. We correlate the Late Cretaceous magmatism in the central Tengchong Block with the northward subduction of the Neo-Tethys beneath the Burma–Tengchong Block.

Application of lanthanides tetrad effect as a geochemical indicator to identify fluorite generations: A case study from the Laal-Kan fluorite deposit, NW Iran

The Laal-Kan fluorite deposit situated in north margin of the Sanandaj-Sirjan metamorphic belt and Urmia-Dokhtar magmatic arc, NW Iran. The fluorite mineralization in the form of open-space filling, veins and veinlets have been deposited in the contact zone between highly metamorphosed schist, gneiss, amphibolite of the Paleozoic age and the Jangutaran limestone of the Precambrian age. The occurrence of convex tetrad effect and the calculated tetrad values indicate that early and late stage fluorite mineralization display various geochemical behavior, which are supported by the bivariate diagrams including T1, T3 and T4 versus each other and some geochemical parameters such as La/Ho, Y/Ho and Zr/Hf ratios. It can, therefore, deduced that fluorite have been probably formed during two stages from hydrothermal fluids with a relatively constant composition. The fluid-rock interaction during deposition of fluorite and REE-F complex were likely the main mechanisms for the occurrence of tetrad effect.

ПЕТРОЛОГИЯ И ГЕОХИМИЯ ИНТРУЗИВНЫХ ПОРОД СИНЮХИНСКОГО МЕСТОРОЖДЕНИЯ (ГОРНЫЙ АЛТАЙ)

New data on phase relationships, petrology and geochemistry of the Sinyukhinskoye rocks and dikes of the same deposit are presented. Five phases of rock intrusions formed in a homodromic-antidromic sequence are found. The Sinyukhinskoye rocks fall in the oxidized type. In the depth, a source of melting was garnet lherzolites, and, to a lesser extent, spinel lherzolites of an enriched mantle source of the lithospheric slab with a degree of partial melting from 0.2 to 0.4 and low pressure. The formation of intrusive rocks of the deposit took place in the post-collisional environment. The magmatite fluids of the massif and dikes were characterized by high partial pressures of such volatile components as H2O, Cl, F, CO2, which were the main carriers of metals. The rocks exhibit the tetrad effect of the W-type REE fractionation. The dependences of the values of the latter and the concentrations of copper and gold in igneous rocks and fluids were determined by different regimes of acidity and alkalinity of the medium. The deposit belongs to a complex family of ores of the copper-gold-skarn-porphyry type. In the Cheryomukhovaya Sopka and Chir areas, this is also confirmed by the presence of the copper-gold-porphyry type in the ore field, in addition to the gold-copperskarn mineralization.

Two Types of Highly Differentiated Topaz-Bearing Granites of the Salmi Batholith, Southern Karelia

Differences between two types of highly differentiated granites of the Salmi batholith: namely Li-siderophyllite topaz-bearing and Li–F topaz-zinnwaldite granites, were determined based on the study of their structural-morphological, mineralogical and geochemical features are determined. The high degree of the differentiation of these granites is confirmed by the presence of primary topaz, Li-micas of magmatic origin and by the presence of significative tetrad effect of M type. These granites are distinguished due to the types of their micas, the content of topaz (up to 1 and 15%, respectively), the morphology of granite intrusions and the geochemistry of rare elements. The Li–F zinnwaldite granites are depleted in REE and enriched in Ta, Hf, Ba, Sr compared to the Li-siderophyllite granites. The Li-siderophyllite granites clearly fit to the general evolution trend of the Salmi batholith granites, while the genesis of Li–F zinnwaldite granites seems to be associated not only with the processes of crystallization differentiation of the melt but also with the active addition of some components, primarily F and Li, probably from a deeper source, including the mantle.

Formation mechanisms of lanthanide tetrad effect in limestones: an example from Arbanos district, NW Iran

The Arbanos Limestone is a part of the Ruteh Formation of Upper Permian age located in NW Iran. No detailed geochemical characterizations of these limestones have been carried out to date. In this research, formation mechanisms of tetrad effect phenomenon in the lanthanide distribution patterns in these limestones are surveyed by applying different geochemical techniques. The mineralogical and geochemical characteristics of the limestones were examined using X-ray diffractometry (XRD) and chemical (ICP–AES and –MS) methods. Mineralogical studies indicate that calcite is the principal constituent accompanied by some minor accessory minerals such as quartz, kaolinite, plagioclase hematite, and smectite in the limestones. Geochemical parameters such as Ca/Mg, Sr, V/Cr, V/(V + Ni), U/Th, Ni/Co, and Mn* reveal that the limestones of the Ruteh Formation were probably deposited in a shallow, oxic, and low salinity environment. The distribution pattern of REE normalized to PAAS (Post Archean Australian Shale) display positive Ce and Eu anomalies in the limestones. The concentration of major and trace elements such as Si, Al, V, Cr, Ni, Rb, Th, U, Y, Zr, and Hf as well as Er/Nd ratio reveal contamination of the limestones by terrigenous materials. Furthermore, strong positive correlations between REE with elements such as Si and Al suggest detrital origin for REE, which is supported by non-seawater like PAAS-normalized REE distribution curves. Some geochemical rations such as Th/Co, Cr/Th, La/Co, Th/Cr, Eu/Eu*, and (La/Lu)N displayed that the terrigenous materials in the limestones were derived from shales of the Ruteh Formation. The zigzag forms in normalized REE patterns and non-CHARAC behavior of Y/Ho and Zr/Hf ratios are another geochemical characteristic of the limestones. According to calculated values for T1, T3 and T4 tetrad effect values reveal the occurrence of tetrad effect phenomenon in REE distribution pattern. Strong positive correlations between T1 and elements such as Hf, U, and V as well as negative correlation with Ca reveal that amount of detrital input and redox potential were likely be responsible for occurrence of lanthanide tetrad effect in the limestone. Meanwhile, strong positive correlations between T3-P, T4-Al, and T4-Nb suggest the important role of diagenetic fluids and contaminations in occurrence of lanthanide tetrad effect in limestones of the Arbanos district.

Radioactivity and Geochemistry of Wadi El Reddah Stream Sediments, North Eastern Desert, Egypt

Wadi El Reddah is considered as semi closed basin where the only open tributary is very narrow and has higher ground relative to the ground adjacent to the surrounding peaks. The 238U activity concentrations range between 101.24 and 347.96 with an average 214.63 Bq Kg-1, 234U activity concentrations range between 89.67 and 308.19 Bq Kg-1 with average 190.10 Bq Kg-1. 232Th activity concentrations vary between 96.42 and 463.71 Bq Kg-1 with 240.46 Bq Kg-1 as an average. 40K ranges between 1092.71 and 1227.25 Bq Kg-1 with an average 1153.82 Bq Kg-1. 235U activity concentration ranges between 4.66 and 17.38 Bq Kg-1 with average 10.19 Bq Kg-1. Most of stream sediment samples exhibit increase in SiO2, Fe2O3t, Na2O, P2O5 and K2O and L.O.I. However, trace elements in the studied samples show enrichment in Ni, Cu, Pb, Zn, Cd, Ta, Nb, Zr, Y, Rb, Cs, Ga, Hf, Sn, Th, Tl, U, W, Mo, Bi, As, Be, Li, Sb and Au whereas they are depleted in Co, Sr, V, Ag, Cr and Sc. Zr, Hf and Y are relatively immobile and essentially concentrated in the accessory minerals (zircon and its alteration product branirite, xenotime, thorite and uranothorite). Their REE patterns are well characterized by the M- and W-type tetrad effects. The M- type tetrad effect could be inherited from the surrounding granitic rocks whereas the positive Y anomalies intimately associating with the W-type tetrad effect of REE mainly occur in natural aquatic solutions including seawaters and in some hydrogenous deposits.

Extreme fractionation and magmatic–hydrothermal transition in the formation of the Abu Dabbab rare-metal granite, Eastern Desert, Egypt

The Abu Dabbab rare-metal granite in the Central Eastern Desert of Egypt is a peraluminous alkali-feldspar leucogranite stock with minimummelt composition of albite-rich haplogranite and is characterized by economic resources of columbite group minerals (CGM) and cassiterite. The bulk-rock trace element composition is characterized by very low Sr, Ba, REE+Y, Zr, Ti, Ni, Cr concentrations, elevated Li and F, and very high Sn, Ta and Ga. The non-chondritic, low Y/Ho ratios and extremely low Nb/Ta and Zr/Hf ratios of the Abu Dabbab granite are consistent with highly evolved peraluminous granites. The chondrite-normalized REE patterns with significant tetrad effects (TE1,3 ~ 1.6–2.6) and strongly negative Eu anomalies are indicative of the magmatic to hydrothermal transition. Heterogeneous 147Sm/144Nd (0.20411–0.51923) and 143Nd/144Nd (0.512968–0.514056) values of the bulk-rock reflect a disturbed Sm-Nd isotope system. Nevertheless, the initial εNd values calculated for a wide range of Neoproterozoic ages (500–700 Ma) are consistently positive, suggesting a juvenile source.Laser ablation ICP-MS analyses of the CGM, cassiterite, wolframite and Mn-ilmenite show elevated rare metal concentrations and complex REE tetrad patterns, reflecting fluid-melt interactions. The metasomatic fluids associated with the Abu Dabbab rare-metal granite were primarily low-salinity (<6 wt.% NaCl eq.), high-density (~0.8–0.9 g/cm3), CO2-rich aqueous fluids with up to ~50 mol% CO2 (+CH4). The minimum entrapment conditions of carbonic-aqueous inclusions are calculated as 2–3 kbar and 350–360°C, whereas aqueous inclusions in the granite and crosscutting quartz veins most likely correspond to lower-pressure conditions and fluid phase separation by decompression. The extreme level of fractionation and complex tetrad effects of the bulk-rock and ore minerals coupled with criteria indicating the magmatic-hydrothermal transition are in accord with regional seismic tomography and heat flow data. A much larger, unexposed parental granite system, from which the exposed Abu Dabbab rare-metal tip has fractionated, must be present at depth. The interaction between extreme fractionation and fluid-melt interaction at shallow crustal levels gave rise to economic-grade Ta-Nb-Sn±W mineralization in the granite body and associated quartz veins.

Ages and genesis of W-Sn and Ta-Nb-Sn-W mineralization associated with the Limu granite complex, Guangxi, China

The Limu granite complex spans three granitic stages, forming the largest Indosinian Ta–Nb–Sn–W ore field in South China. There includes quartz-vein WSn (type-1) mineralization associated with second-stage granite, as well as Ta–Nb–Sn–W mineralization associated with third-stage granite including quartz–feldspar-vein (type-2), pegmatite dike (type-3), and disseminated (type-4) mineralization. To elucidate the magmatic evolution and genesis of these types of mineralization, we obtained muscovite 40Ar/39Ar ages, zircon LA–ICP–MS UPb ages, and LuHf and Nd isotopic, trace-element, and geochemical compositions of the Limu granite complex. The Limu granites are peraluminous (A/CNK > 1.1) with negative ɛNd(t) values (−8.5 to −9.7) and TDM2 ages of 1780–1685 Ma, suggesting that they were derived mainly from partial melting of Paleoproterozoic basement. Remnants of Caledonian zircons (429.4 ± 5.6 Ma) indicate Caledonian granite melting in the source. Low Zr/Hf (<13) and Nb/Ta (<5) ratios and the tetrad effect in rare-earth-element patterns of the second- and third-stage granites indicate that the magmas were highly evolved and underwent late-stage exsolution of fluids. Muscovite from type-1 ore yielded an 40Ar/39Ar age of 213.7 ± 1.1 Ma. Two hydrothermal zircons and two muscovite samples from third-stage granite containing type-4 mineralization yielded similar UPb ages of ca. 203 Ma and 40Ar/39Ar ages of ca. 208 Ma, respectively. We conclude that type-1 mineralization was formed at ca. 214 Ma and was hydrothermal in origin, whereas Ta–Nb–Sn–W mineralization was formed at ca. 208–203 Ma and was of magmatic-hydrothermal origin. Mantle-derived heat from a long-lived magma chamber was essential for the high-temperature anatexis that formed Ta–Nb–Sn–W-rich melts, with the combined effects of crustal thickening during the Indosinian Orogeny, local delamination, asthenospheric upwelling, and deep faulting facilitating the continuous supply of heat.

Highly fractionated Himalayan leucogranites and associated rare-metal mineralization

The formation of the Himalaya was associated with the exhumation of high-grade metamorphosed rocks of the Higher Himalayan sequence (HHS) complex, which underwent amphibolite-, granulite- to eclogite-facies metamorphism and anatexis. Occurring along the Himalayan mountain crest in the south and the Lhagoi Kangri mountain in the north, the Himalayan leucogranites contain varying proportions of biotite (<5%), muscovite, tourmaline, and garnet, and are typically equigranular in texture with variable structures from foliated to massive. These peraluminous granites have been interpreted as purely crust-derived melts, without any input from the mantle, and may therefore record the timing of continental collision. However, they were emplaced between 44 and 7 Ma, much later than the timing of collision between India and Asia (c. 60 Ma). Although typically interpreted as products of in situ partial melting of the HHS during subduction and exhumation, we suggest that the Himalayan leucogranites underwent intense crystal fractionation, as recorded by crystal layering, sedimentary-like cross-bedding, and the occurrence of pegmatites with varying grain sizes. Geochemically, these leucogranites are low in siderophile but high in lithophile elements, with significant negative europium (Eu) anomalies, non-chondritic Nb/Ta and Zr/Hf ratios, and rare earth element (REE) tetrad effects. Many of the leucogranites and pegmatites contain rare-metal minerals, such as beryl and chrysoberyl; columbite–tantalite, tapiolite, and pyrochlore–microlite; rutile and fergusonite; and zinnwaldite, lepidolite, spodumene, and petalite, supporting an origin involving a high degree of magmatic fractionation. We suggest that the primary magma was generated through partial melting of subducted Indian crust due to input of heat from depth. The generation of magma triggered the exhumation of the Indian crust and subsequent formation of the Himalayan mountain chain. The magma ascended with the Indian crust along the South Tibetan Detachment System (STDS), during which time it underwent significant fractionation. Anatectic melts generated from exhumed Indian crust through decompression melting are distinct from the leucogranites, indicating that exhumation of the Indian crust had a limited contribution to the generation and evolution of the leucogranites. Extensional faulting facilitated a high degree of magma fractionation and rare-metal mineralization.

Indosinian magmatism and rare metal mineralization in East Tianshan orogenic belt: An example study of Jingerquan Li-Be-Nb-Ta pegmatite deposit

The East Tianshan orogenic belt, a part of the Central Asian Orogenic Belt like Altai orogenic belt, has shown great potential for rare metal mineralization. Jingerquan Li-Be-Nb-Ta deposit is the largest pegmatite deposit in this region. Muscovite granite, quartz monzonite and gabbro have developed in the Jingerquan Li-Be-Nb-Ta pegmatite deposit in the eastern part of East Tianshan orogenic belt. Based on the content of elemental Li and the presence of Li-bearing minerals, we recognize two sets of intrusive assemblages, namely, class I, including muscovite granite and quartz monzonite, which are rich in Li with presence of spodumene and/or lepidolite, and class II mainly gabbro, which are poor in Li and absent of Li-bearing minerals. Class I rocks are rich in Si, Al, Na, K, calc-alkaline to high-K calc-alkaline series, and poor in Ca, P, Fe, and Mg, with A/CNK ≥ 1.1, which are similar to S-type peraluminous granites. Class I rocks are characterized by Rb, Ta, Nb, and Hf enrichments and significant Ti, Ba, and Sr depletions. The chondrite-normalized rare earth element (REE) patterns exhibit significant Eu anomalies (δEu = 0.01–0.20), “tetrad effect,” and increased fractionation of rare earth elements with relatively low ΣREE. Class II rocks are calc-alkaline rocks that are rich in Ca, Al, and P and poor in Si, K, with A/CNK < 1; they are characterized by Ba and Sr enrichments and Th, Nb, and Ta depletions. The chondrite-normalized REE patterns exhibit no significant Eu anomalies (δEu = 0.97–1.40) and a smooth curve that slopes to the right. The monazite SIMS U-Th-Pb ages of class I (246–252.9 Ma) and the zircon LA-ICP-MS U-Pb ages of class II (247–250.7 Ma) indicate that both types of intrusions were formed in intraplate environment in Indosinian period. The εHf(t) values (12.0–15.2) and the depleted mantle model ages TDM (279–411 Ma) of class II rocks indicate that the magmas were mainly derived from partial melting of the depleted mantle. In the intraplate extensional setting, the mantle magmas represented by class II basaltic magmas intraplated into the crust and induced partial melting of the middle and upper crust to produce class I S-type granitic magmas. After that, the granitic magmas underwent continuous differential evolution and volatile enrichment, and finally form Li-Be-Nb-Ta mineralized granitic pegmatite. The geological setting, diagenetic and metallogenic chronology, and mineral assemblages of the East Tianshan orogenic belt and the Altai orogenic belt can be compared, and rare metal mineralization of both belts were controlled by the Indosinian tectonic-magmatic event.

Mesozoic crustal growth in Mainland Southeast Asia: Zircon U-Pb and Hf isotopic evidence from the Late Cretaceous Luyingtang granitic pluton in the northernmost SE Asian granite Province, SW China

The Changning-Menglian suture in the Sanjiang region of SW China, the Chiang Rai line in Thailand, and the Bentong-Raub suture in Peninsular Malaysia are marked by remnants of the Paleo-Tethys oceanic lithosphere in Mainland Southeast Asia. We present U-Pb ages and Hf isotopic compositions of zircon from Luyingtang granites east of the Changning-Menglian suture, with the aim of identifying their sources and petrogenesis, which are significant for understanding the crustal evolution of the Mainland Southeast Asia. The Luyingtang granitic pluton is located in the northernmost SE Asian granite Province, SW China. New zircon U-Pb ages indicate that the granites were emplaced in the Late Cretaceous, in accordance with the regional scale inland magmatic event in Mainland Southeast Asia. Petrographically, the samples range from granodiorite, biotite granite, two-mica granite to pegmatite. The biotite granite, two-mica granite and pegmatite have low contents of TiO2, Al2O3, FeO*, MgO, CaO and P2O5, but high values of SiO2 and K2O, compared to the granodiorite. The granodiorite, biotite granite and two-mica granite invariably show enrichment in light rare earth elements (LREE). The biotite granite and two-mica granite show negative Eu anomalies, but the granodiorite displays weak Eu anomaly. The pegmatites show a clear tetrad effect and contain pronounced negative Eu anomalies. All the rocks demonstrate characteristic negative Nb, Ta, Sr and Ti anomalies, and a positive Pb anomaly, when plotted on spidergrams. Most of the granites are characterized by positive εHf (t) values (0.3–8) and fairly young TDM2 ages (612–1094 Ma), suggesting they contain a significant proportion of juvenile component. Hf isotopic modelling shows that the Luyingtang granites are likely to have been produced by partial melting of mixed sources, which were probably of basalts in proportions of 50–70% and Precambrian continental crust. The emplacement of granites with such a large proportion of mantle-derived component indicates crustal growth in Mainland Southeast Asia during Mesozoic. In contrast, one of the two-mica granite samples displays negative εHf (t) values (−7.6 to −3) and older TDM2 ages (1305–1599 Ma), which suggest a more crustal affinity. The arc-continent collision during the Cretaceous may have induced foundering of an over-thickened lithospheric mantle keel beneath the Paleo-Tethys orogenic belt, and then resulted to localized upwelling of asthenosphere mantle and basaltic underplating. The parental magmas of the hinterland I-type granites formed by melting of a mixed source, containing both Precambrian crust and mantle-derived basalt, followed by extensive magmatic differentiation.

Generation of leucogranites via fractional crystallization: A case study of the Jurassic Bengbu granite in the southeastern North China Craton

The magmatic processes that form leucogranites are closely related to plate collision. As the products of crustal anatexis, leucogranites provide clues to intracrustal differentiation and the regional tectonic evolution. The Bengbu area is located along the southeastern margin of the North China Craton (NCC), 150 km north of the Dabie Orogen, and is bounded by the Tancheng–Lujiang Fault Zone to the east. Late Jurassic leucogranites are widely distributed in the Bengbu area. We collected samples of the Bengbu leucogranite (BLG) and analyzed data on whole-rock geochemistry, zircon U–Pb geochronology, zircon in situ Lu–Hf isotopes, quartz in situ O isotopes, and total bulk Sr–Nd–Pb isotopes. Zircon U–Pb dating yielded formation ages for these leucogranites of ∼160 Ma. The samples are characterized by high SiO2 (72.4 wt.%−76.9 wt.%), alkali (7.3 wt.%−9.4 wt.%), and Al2O3 (13.4 wt.%−15.5 wt.%) contents. In addition to two samples exhibiting the rare-earth element tetrad effect, all rocks have high differentiation index values (95–99), extremely low iron–magnesium–titanium oxide contents (total Fe2O3 < 1.4 wt.%, MgO < 0.3 wt.%, TiO2 < 0.2 wt.%), and low Zr/Hf (20–50) and Nb/Ta (5–25) ratios. These data suggest that the BLG is a highly fractionated granite. Furthermore, the samples contain Neoproterozoic and Triassic zircons, have low Ti-in-zircon temperatures (682–697 °C), low Rb contents (<192 ppm), high Sr contents (48–791 ppm), low Rb/Sr ratios, low radiogenic Pb isotopic compositions (206Pb/204Pb(t) = 17.169–17.297), and highly enriched Sr–Nd–Hf isotopic compositions (87Sr/86Sr(t) = 0.7082–0.7104, εNd(t) = −16.6 to −12.3, and zircon εHf(t) = −14.5 to −21.7). Taken together, the geochronological and geochemical results suggest that the BLG was formed by high-degree fractional crystallization after hydrous partial melting of the North Dabie granitic gneisses, which have been subducted beneath the Bengbu area by Triassic continental subduction. Following collision between the South China Block and the NCC, Late Jurassic granitoids in the eastern NCC, including the BLG, were generated in the resulting post-orogenic extensional environment and were also influenced by ongoing subduction and rollback of the Izanagi Plate.