Geologica acta

Geologica acta 6 records found  Search took 0.01 seconds. 
1.
14 p, 2.7 MB Tourmaline 40Ar/39Ar chronology of tourmaline-rich rocks from Central Iberia dates the main Variscan deformation phases / Bea, F. (Universidad de Granada. Departamento de Mineralogía y Petrología) ; Pesquera, A. (Universidad del País Vasco. Departamento de Mineralogía y Petrología) ; Montero, P. (Universidad de Granada. Departamento de Mineralogía y Petrología) ; Torres-Ruiz, J. (Universidad de Granada. Departamento de Mineralogía y Petrología) ; Gil-Crespo, P. P. (Universidad del País Vasco. Departamento de Mineralogía y Petrología)
During crustal thickening, metapelites taken to depth release boron-bearing hydrothermal fluids because of progressive heating and dehydration. These fluids swiftly percolate upwards, especially if the crust is being actively deformed, to form tourmaline where the PT conditions and the chemical composition of the host-rock are favorable. [...]
2009 - 10.1344/104.000001446
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 399-412  
2.
17 p, 1.4 MB Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) / González-Jiménez, J.M. (Universidad de Granada. Departamento de Mineralogía y Petrología and Instituto Andaluz de Ciencias de la Tierra) ; Kerestedjian, T. (Bulgarian Academy of Sciences. Geological Institute) ; Proenza, J.A. (Universitat de Barcelona. Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals) ; Gervilla, F. (Universidad de Granada. Departamento de Mineralogía y Petrología and Instituto Andaluz de Ciencias de la Tierra)
Podiform chromitite bodies occur in highly serpentinized peridotites at Dobromirtsi Ultramafic Massif (Rhodope Mountains, southeastern Bulgaria). The ultramafic body is believed to represent a fragment of Palaeozoic ophiolite mantle. [...]
2009 - 10.1344/104.000001447
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 413-429  
3.
19 p, 3.6 MB In situ thermochemical sulfate reduction during ore formation at the Itxaspe Zn-(Pb) MVT occurrence (Basque-Cantabrian basin, Northern Spain) / Piqué, À. (Universitat de Barcelona. Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals) ; Canals, À. (Universitat de Barcelona. Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals) ; Disnar, J.R. (Université d'Orléans. Institut des Sciences de la Terre d'Orléans) ; Grandia, F. (Amphos 21)
Organic matter is thought to play a role in the genesis of many Mississippi Valley-type (MVT) deposits, acting as a reducing agent during thermochemical sulfate reduction (TSR). Although TSR is an extremely slow reaction t low temperatures (<100ºC), under favorable conditions it may supply the necessary reduced sulfur during ore formation. [...]
2009 - 10.1344/105.000001448
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 431-449  
4.
23 p, 1.7 MB Paleogeographic inversion resulting from large out of sequence breaching thrusts: The León Fault (Cantabrian Zone, NW Iberia). A new picture of the external Variscan Thrust Belt in the Ibero-Armorican Arc / Alosno, J.L. (Universidad de Oviedo. Departamento de Geología) ; Marcos, A. (Universidad de Oviedo. Departamento de Geología) ; Suárez, A. (Instituto Geológico y Minero de España)
Out of sequence breaching thrusts may give rise to duplication of a former thrust stack in map view in the same manner that stratigraphic units are repeated by initial thrusts. In this way, large breaching thrusts may put an inicial paleogeographic pattern out of order, producing apparent paleogeographic inversions at regional scale. [...]
2009 - 10.1344/105.000001449
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 451-473  
5.
13 p, 2.6 MB Late Miocene karst system at Sheikh Abdallah, between Bahariya and Farafra, Western Desert, Egypt : Implications for palaeoclimate and geomorphology / Wanas, H.A. (Menoufia University. Faculty of Science) ; Pickford, M. (Collège de France) ; Mein, P. (Université Claude Bernard. Département des Sciences de la Terre) ; Soliman, H. (Menoufia University. Faculty of Science) ; Pickford, M. (Collège de France) ; Segalen, L. (Université Pierre et Marie Curie)
The extensive spelean deposits in the Western Desert of Egypt at Crystal Mountain (Gebel Bellorat) are considered to be 11-10 Ma, confirming the 'Vallesian' estimate made by Heissig (1982). Several new faunal elements have been discovered including anurans, snakes, soricids, bats, galagids, hystricids and glirids. [...]
2009 - 10.1344/105.000001450
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 475-487  
6.
16 p, 6.2 MB Taphonomy of a Mysticeti whale in the Lower Pliocene Huelva Sands Formation (Southern Spain) / Esperante, R. (Geoscience Research Institute) ; Muñiz Guinea, F. (Universidad de Huelva. Grupo de Investigación RNM 316 "Tectónica y Paleontología") ; Nick, K.E. (Loma Linda University. Department of Earth and Biological Sciences)
This paper reports the occurrence of an incomplete fossil baleen whale skeleton in the Lower Pliocene Huelva Sands Formation (Guadalquivir basin) near the town of Bonares, southwestern Spain. The skeleton was found in the highly bioturbated glauconitic sandstone unit in association with Neopycnodonte cochlear shells. [...]
2009 - 10.1344/105.000001451
Geologica acta, Vol. 7, Núm. 4 (Desembre 2009) , p. 489-505  

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