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Determination of the emplacement ages and initial isotopic composition of kimberlite by conventional isotopic methods using bulk rock samples is unreliable as these rocks usually contain diverse clasts of crustal- and mantle-derived materials and can be subject to post-intrusion sub-aerial alteration. In this study, 8 samples from 5 kimberlites in southern Africa and twelve samples from 7 kimberlites...
The intrusion of granitoids into the Eastern Sierras Pampeanas in the Early Carboniferous took place after a long period of mainly compressional deformation that included the Famatinian (Ordovician) and Achalian (Devonian) orogenies. These granitoids occur as small scattered plutons emplaced in a dominant extensional setting, within older metamorphic and igneous rocks, and many of them are arranged...
We describe a rare terrestrial occurrence of hibonite (CaAl 12 TiO 19 ) from the ultrapotassic rocks which occur as veinlets in graphite-bearing spinellite in the Achankovil Shear Zone (ACSZ), southern India. The ultrapotassic rocks are characterized by an unusual mineral assemblage, kalsilite + leucite + corundum + spinel + perovskite + apatite + hibonite ± phlogopite, along with...
North Xinjiang, Northwest China, is made up of several Paleozoic orogens. From north to south these are the Chinese Altai, Junggar, and Tian Shan. It is characterized by widespread development of Late Carboniferous–Permian granitoids, which are commonly accepted as the products of post-collisional magmatism. Except for the Chinese Altai, East Junggar, and Tian Shan, little is known about the Devonian...
Sub-continental type gabbro preserving an eclogite facies assemblage and glaucophane–garnet bearing micaschist from the eastern border of the Gran Paradiso Massif (Western Alps) have been investigated to constrain its tectono-metamorphic evolution. Glaucophane-bearing metapelites were never reported before while metagabbros are only found in the southern part of the Massif. Growth zoning of multistage...
Rutile and zircon in eclogites from the main hole of the Chinese Continental Scientific Drilling (CCSD-MH) were analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron microprobe (EMP). Both single spot and profile analyses of large matrix rutiles (>60μm) generally demonstrate core–rim variability of Pb, Sr, Zr and U. Pb and Sr show enrichment at the rims,...
The 2.7Ga Kambalda Sequence is a mafic and ultramafic volcanic sequence in the Kalgoorlie Terrane of the Yilgarn craton, Western Australia. The Sequence is divided into the Lower Basalt and Upper Basalt Units, separated by the komatiite lava flow units, and was erupted onto an autochthonous volcanic sequence, the 2.8Ga Penneshaw Formation. The Lower Basalt Unit includes six basalt suites or formations...
This paper presents and discusses the results of an integrated structural and petrological study, in order to delineate the entire tectono metamorphic history of a still little-known crystalline fragment of the southern Hercynian European Belt, currently framed within the central Mediterranean region after the superposition of the Alpine tectonics.These results were obtained by correlating P–T constraints...
Three plutons (Deh-Siahan, Bande-Bagh and Baghe-Khoshk Sharghi, collectively referred to as the DBB hereafter) in southwestern Kerman, in the southeastern part of the Urumieh–Dokhtar magmatic assemblage (UDMA) of the Zagros orogenic belt differ from the typical calc-alkaline metaluminous, I-type intrusions of the region. The DBB intrusions have a distinct lithological assemblage varying from diorite...
In this paper we present new LA-MC–ICPMS U–Pb and Lu–Hf isotope data on zircon from three Svecofennian leucogranites of alleged S-type affinity from southern Finland: the Jaani, Perniö and Puruvesi granites. The results show that these granites were emplaced at about 1.86Ga, 1.84Ga and 1.79Ga, respectively. The Jaani and Puruvesi plutons also contain inherited zircon with Paleoproterozoic and Archean...
This paper investigates the mineralogical effects of hydrothermal alteration at depth in fractures in granite. A fracture accompanied by an alteration halo and filled with clay was found at a depth of 200m in a drill core through Toki granite, Gifu, central Japan. Microscopic observation, XRD, XRF, EPMA and SXAM investigations revealed that the microcrystalline clays consist of illite, quartz and...
We present U–Pb zircon age determinations of two Variscan ultrapotassic plutonic rocks from the Moldanubian Zone (Bohemian Massif). Equant, multifaceted zircons without inherited cores from a two-pyroxene–biotite quartz monzonite of the Jihlava Pluton yielded a precise age of 335.12±0.57Ma, interpreted as dating magma crystallization. The majority of both tabular and prismatic grains from the amphibole–biotite...
The unconformity-type uranium deposits of the Athabasca Basin (Saskatchewan, Canada) are hosted near the unconformity between a middle Proterozoic intracratonic sedimentary basin and an Archean to Paleo-Proterozoic metamorphic and plutonic basement. These deposits, which are considered to be the richest U deposits in the world, are the result of massive basinal fluid migrations in the basement rocks...
Late Tertiary to Quaternary basaltic rocks from three locations in interior Alaska — Fort Hamlin Hills, Prindle Volcano, and Buzzard Creek — have been characterized geochemically using major and trace element concentrations and radiogenic isotopic ratios. The rocks from Fort Hamlin Hills and Prindle Volcano have well-constrained 40 Ar/ 39 Ar eruption ages ranging from 32.83±0.16Ma...
Neoarchean late to post-tectonic sanukitoid intrusions are found in the western part of the Karelian Province in Finland. Variable-sized, even-grained to K-feldspar porphyritic intrusions form a series of diorites, tonalites, and granodiorites, that are calc-alkaline to alkali-calcic, magnesian, and mostly peraluminous. The major and trace element geochemistry of the intrusions show typical sanukitoid...
The origin of the New Caledonia ophiolite (South West Pacific), one of the largest in the world, is controversial. This nappe of ultramafic rocks (300km long, 50km wide and 2km thick) is thrust upon a smaller nappe (Poya terrane) composed of basalts from mid-ocean ridges (MORB), back arc basins (BABB) and ocean islands (OIB). This nappe was tectonically accreted from the subducting plate prior and...
The origin of kimberlites and volatile-rich alkaline ultramafic magmas such as aillikites has been a matter of considerable scientific interest and the recent paper by Francis and Patterson (Francis and Patterson, 2009. Kimberlites and Aillikites as probes of the continental lithospheric mantle. Lithos 109, 72–80) attempts to summarize advances in this research field. They introduce new major element...
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