TY - JOUR A1 - Zozulya, Dmitry R. A1 - Kullerud, Kare A1 - Ribacki, Enrico A1 - Altenberger, Uwe A1 - Sudo, Masafumi A1 - Savchenko, Yevgeny E. T1 - The newly discovered neoproterozoic aillikite occurrence in Vinoren (Southern Norway) BT - age, geodynamic position and mineralogical evidence of diamond-bearing mantle source JF - Minerals N2 - During the period 750-600 Ma ago, prior to the final break-up of the supercontinent Rodinia, the crust of both the North American Craton and Baltica was intruded by significant amounts of rift-related magmas originating from the mantle. In the Proterozoic crust of Southern Norway, the 580 Ma old Fen carbonatite-ultramafic complex is a representative of this type of rocks. In this paper, we report the occurrence of an ultramafic lamprophyre dyke which possibly is linked to the Fen complex, although Ar-40/Ar-39 data from phenocrystic phlogopite from the dyke gave an age of 686 +/- 9 Ma. The lamprophyre dyke was recently discovered in one of the Kongsberg silver mines at Vinoren, Norway. Whole rock geochemistry, geochronological and mineralogical data from the ultramafic lamprophyre dyke are presented aiming to elucidate its origin and possible geodynamic setting. From the whole-rock composition of the Vinoren dyke, the rock could be recognized as transitional between carbonatite and kimberlite-II (orangeite). From its diagnostic mineralogy, the rock is classified as aillikite. The compositions and xenocrystic nature of several of the major and accessory minerals from the Vinoren aillikite are characteristic for diamondiferous rocks (kimberlites/lamproites/UML): Phlogopite with kinoshitalite-rich rims, chromite-spinel-ulvospinel series, Mg- and Mn-rich ilmenites, rutile and lucasite-(Ce). We suggest that the aillikite melt formed during partial melting of a MARID (mica-amphibole-rutile-ilmenite-diopside)-like source under CO2 fluxing. The pre-rifting geodynamic setting of the Vinoren aillikite before the Rodinia supercontinent breakup suggests a relatively thick SCLM (Subcontinental Lithospheric Mantle) during this stage and might indicate a diamond-bearing source for the parental melt. This is in contrast to the about 100 Ma younger Fen complex, which were derived from a thin SCLM. KW - aillikite KW - phlogopite KW - carbonate KW - spinel KW - ilmenite KW - titanite KW - diamond KW - Vinoren KW - Southern Norway Y1 - 2020 U6 - https://doi.org/10.3390/min10111029 SN - 2075-163X VL - 10 IS - 11 PB - MDPI CY - Basel ER - TY - JOUR A1 - Zobir, Soraya Hadj A1 - Altenberger, Uwe A1 - Günter, Christina T1 - Geochemistry and petrology of metamorphosed submarine basic ashes in the Edough Massif (Cap de Garde, Annaba, northeastern Algeria) JF - Comptes rendus geoscience N2 - The study presents the first evidence of metamorphosed submarine ashes in the Edough Massif, in northeastern Algeria. It occurs below the greenschist-facies Tellian units that represent the thrusted Mesozoic to Eocene passive paleomargin of northern Africa deposited on thinned continental crust. The metamorphic complex consists of tectonically superposed units composed of gneisses (lower unit) and micaschists (upper unit). At the Cap de Garde, these units enclose an "intermediate unit" composed of micaschists and meter-thick layers of marbles, which are sometimes intercalated with amphibolites. The latter occur as discontinuous small lenses and layers. The amphibolites are parallel to the primary bedding of the marbles and the main foliation. Chemical markers and field observations indicate that they are metamorphic equivalents of basic igneous rocks. The lenticular character, low thickness and multiple intercalations with marine sediments and the unusual high lithium concentrations suggest subaqueous near-source basaltic ash-fall deposits in a marine environment. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved. KW - Amphibolites KW - Submarine sediments KW - Basaltic ash-fall deposits KW - Edough KW - Algeria Y1 - 2014 U6 - https://doi.org/10.1016/j.crte.2014.09.002 SN - 1631-0713 SN - 1778-7025 VL - 346 IS - 9-10 SP - 244 EP - 254 PB - Elsevier CY - Paris ER - TY - JOUR A1 - Yu, S. A1 - Altenberger, Uwe A1 - Sun, Y. T1 - Petrology, geochemistry, and tectonic setting of the Shangdan Metamorphic Sandstone ; Shangdan Suture Zone, Qinling Mountains (Central) Y1 - 1998 ER - TY - JOUR A1 - Wilke, Franziska Daniela Helena A1 - O'Brien, Patrick J. A1 - Altenberger, Uwe A1 - Konrad-Schmolke, Matthias A1 - Khan, M. Ahmed T1 - Multi-stage reaction history in different eclogite types from the Pakistan Himalaya and implications for exhumation processes N2 - Metabasites were sampled from rock series of the subducted margin of the Indian Plate, the so-called Higher Himalayan Crystalline, in the Upper Kaghan Valley, Pakistan. These vary from corona dolerites, cropping out around Saif- ul-Muluk in the south, to coesite-eclogite close to the suture zone against rocks of the Kohistan arc in the north. Bulk rock major- and trace-element chemistry reveals essentially a single protolith as the source for five different eclogite types, which differ in fabric, modal mineralogy as well as in mineral chemistry. The study of newly-collected samples reveals coesite (confirmed by in situ Raman spectroscopy) in both garnet and omphacite. All eclogites show growth of amphiboles during exhumation. Within some coesite-bearing eclogites the presence of glaucophane cores to barroisite is noted whereas in most samples porphyroblastic sodic-calcic amphiboles are rimmed by more aluminous calcic amphibole (pargasite, tschermakite, and edenite). Eclogite facies rutile is replaced by ilmenite which itself is commonly surrounded by titanite. In addition, some eclogite bodies show leucocratic segregations containing phengite, quartz, zoisite and/or kyanite. The important implication is that the complex exhumation path shows stages of initial cooling during decompression (formation of glaucophane) followed by reheating: a very similar situation to that reported for the coesite-bearing eclogite series of the Tso Morari massif, India, 450 km to the south-east. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00244937 U6 - https://doi.org/10.1016/j.lithos.2009.07.015 SN - 0024-4937 ER - TY - JOUR A1 - Wilhelm, Stefan A1 - Altenberger, Uwe A1 - Oberhänsli, Roland T1 - Intrusive marbles in the Ivrea Zone (Italy) : evidence for melting of metacarbonates Y1 - 2001 ER - TY - JOUR A1 - Wendt, A. S. A1 - Altenberger, Uwe A1 - D'arco, T1 - Radial cracks around chromite inclusions in olivine : a new geothermobarometer based on the thermoelastic properties of chromite and forsterite-rich olivine Y1 - 1998 ER - TY - JOUR A1 - Weidinger, Johannes T. A1 - Korup, Oliver A1 - Munack, Henry A1 - Altenberger, Uwe A1 - Dunning, Stuart A. A1 - Tippelt, Gerold A1 - Lottermoser, Werner T1 - Giant rockslides from the inside JF - Earth & planetary science letters N2 - The growing body of research on large-scale mass wasting events so far has only scarcely investigated the sedimentology of chaotic deposits from non-volcanic terrestrial landslides such that any overarching and systematic terminological framework remains elusive. Yet recent work has emphasized the need for better understanding the internal structure and composition of rockslide deposits as a means to characterise the mechanics during the final stages of runout and emplacement. We offer a comprehensive overview on the occurrence of rock fragmentation and frictional melt both at different geographic locations, and different sections within large (>10(6) m(3)) rockslide masses. We argue that exposures of pervasively fragmented and interlocked jigsaw-cracked rock masses; basal melange containing rip-up clasts and phantom blocks; micro-breccia; and thin bands of basal frictionite are indispensable clues for identifying deposits from giant rockslides that may remain morphologically inconspicuous otherwise. These sedimentary assemblages are diagnostic tools for distinguishing large rockslide debris from macro and microscopically similar glacial deposits, tectonic fault-zone breccias, and impact breccias, and thus help avoid palaeoclimatic and tectonic misinterpretations, let alone misestimates of the hazard from giant rockslides. Moreover, experimental results from Mossbauer spectroscopy of frictionite samples support visual interpretations of thin sections, and demonstrate that short-lived (<10 s) friction-induced partial melting at temperatures >1500 degrees C in the absence of water occurred at the base of several giant moving rockslides. This finding supports previous theories of dry excess runout accompanied by comminution of rock masses down to gm-scale, and indicates that catastrophic motion of large fragmenting rock masses does not require water as a potential lubricant. KW - landslide KW - petrography KW - frictional melt KW - pseudotachylyte KW - breccia KW - Mossbauer spectroscopy Y1 - 2014 U6 - https://doi.org/10.1016/j.epsl.2013.12.017 SN - 0012-821X SN - 1385-013X VL - 389 SP - 62 EP - 73 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Weber, Marion A1 - Cardona, A. A1 - Valencia, V. A1 - Altenberger, Uwe A1 - Lopez-Martinez, M. A1 - Tobon, M. A1 - Zapata, Sebastian Henao A1 - Zapata, G. A1 - Concha, A. E. T1 - Geochemistry and geochronology of the Guajira Eclogites, northern Colombia evidence of a metamorphosed primitive Cretaceous Caribbean Island-arc JF - Geologica acta N2 - The chemical composition of eclogites, found as boulders in a Tertiary conglomerate from the Guajira Peninsula, Colombia suggests that these rocks are mainly metamorphosed basaltic andesites. They are depleted in LILE elements compared to MORB, have a negative Nb-anomaly and flat to enriched REE patterns, suggesting that their protoliths evolved in a subduction related tectonic setting. They show island-arc affinities and are similar to primitive island-arc rocks described in the Caribbean. The geochemical characteristics are comparable to low-grade greenschists from the nearby Etpana Terrane, which are interpreted as part of a Cretaceous intra-oceanic arc. These data support evidence that the eclogites and the Etpana terrane rocks formed from the same volcano-sedimentary sequence. Part of this sequence was accreted onto the margin and another was incorporated into the subduction channel and metamorphosed at eclogite facies conditions. Ar-40-Ar-39 ages of 79.2 +/- 1.1Ma and 82.2 +/- 2.5Ma determined on white micas, separated from two eclogite samples, are interpreted to be related to the cooling of the main metamorphic event. The formation of a common volcano-sedimentary protolith and subsequent metamorphism of these units record the ongoing Late Cretaceous continental subduction of the South American margin within the Caribbean intra-oceanic arc subduction zone. This gave way to an arc-continent collision between the Caribbean and the South American plates, where this sequence was exhumed after the Campanian. KW - Eclogites KW - Primitive island-arc KW - Geochronology KW - Guajira Peninsula KW - Colombia KW - Caribbean Y1 - 2011 U6 - https://doi.org/10.1344/105.000001740 SN - 1695-6133 VL - 9 IS - 3-4 SP - 425 EP - 443 PB - Facultat de Geologia, Divisio III, Ciències Experimentals i Matemàtiques, Universitat de Barcelona CY - Barcelona ER - TY - JOUR A1 - Vßsquez, Mónica A1 - Altenberger, Uwe A1 - Romer, Rolf L. T1 - Neogene magmatism and its possible causal relationship with hydrocarbon generation in SW Colombia N2 - The Cretaceous oil-bearing source and reservoir sedimentary succession in the Putumayo Basin, SW Colombia, was intruded by gabbroic dykes and sills. The petrological and geochemical character of the magmatic rocks shows calc- alkaline tendency, pointing to a subduction-related magmatic event. K/Ar dating of amphibole indicates a Late Miocene to Pliocene age (6.1 +/- A 0.7 Ma) for the igneous episode in the basin. Therefore, we assume the intrusions to be part of the Andean magmatism of the Northern Volcanic Zone (NVZ). The age of the intrusions has significant tectonic and economic implications because it coincides with two regional events: (1) the late Miocene/Pliocene Andean orogenic uplift of most of the sub-Andean regions in Peru, Ecuador and Colombia and (2) a pulse of hydrocarbon generation and expulsion that has reached the gas window. High La/Yb, K/Nb and La/Nb ratios, and the obtained Sr-Nd-Pb isotopic compositions suggest the involvement of subducted sediments and/or the assimilation of oceanic crust of the subducting slab. We discuss the possibility that magma chamber(s) west of the basin, below the Cordillera, did increase the heat flow in the basin causing generation and expulsion of hydrocarbons and CO2. Y1 - 2009 UR - http://www.springerlink.com/content/103695 U6 - https://doi.org/10.1007/s00531-008-0303-6 SN - 1437-3254 ER - TY - JOUR A1 - Vasquez, Mónica A1 - Altenberger, Uwe A1 - Romer, Rolf L. A1 - Sudo, Masafumi A1 - Moreno-Murillo, Juan Manuel T1 - Magmatic evolution of the Andean Eastern Cordillera of Colombia during the Cretaceous : Influence of previous tectonic processes N2 - The Eastern Cordillera of the Colombian Andes represents an inverted Cretaceous basin where Cretaceous magmatism is characterized by rare mafic dykes and sills. We use Ar-40/Ar-39, Sr-Nd-Pb isotopes, as well as major and trace elements analyses of Cretaceous intrusions from both flanks of the Eastern Cordillera in combination with structural data to document the complex evolution of the basin. Magmatism, which is diachronous and geochemically diverse, seems to be related to mantle melting beneath the most subsiding segments of each sub-basin during enhanced extensional tectonics. The mafic intrusions display two different compositional series: an alkaline one with OIB-like pattern and a tholeiitic one with MORB-like features. This indicates at least two diverse mantle sources. Trace-element patterns suggest that the intrusions were emplaced in an extensional setting. Ar-40/Ar-39 dating on primary plagioclase and hornblende provides plateau ages between similar to 136 and similar to 74 Ma. The geochemical and temporal diversities show that the emplacement of the magmas was tectonically controlled, each sub-basin reflecting an individual subsidence event. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/08959811 U6 - https://doi.org/10.1016/j.jsames.2009.02.003 SN - 0895-9811 ER -