Mingling and mixing features in basaltic Andesites of the Eastern Cordillera (Central Andes, 24°s): a petrographic and microanalytical study

The basaltic andesites of the Diego de Almagro volcanic complex (Central Andes, 24°S, 66°W) were erupted during Late Miocene at 300 km from the active arc, in the Eastern Cordillera, at the easternmost end of an important strike-slip structure, the Calama-Olocapato-El Toro. These volcanic rocks preserved traces of their pristine history in the form of xenocrysts and in the diverse populations of phenocrysts coexisting due to magma mixing. In Central Andes, crustal contamination commonly conditions the composition of magmas ascending through the thick continental crust, masking the characteristics of the mantle sources. Thus, we carried out detailed petrography and mineral chemistry studies on selected Diego de Almagro basaltic andesites, with the aim to identify the populations of crystals in equilibrium with mafic melts. The results suggested that mixing of basaltic and andesitic magmas occurred during the ascent and storage in the crust. The fraction of basaltic magma prevailed in the mixing process compared to the andesitic one. Crystal zoning and disequilibrium features indicate that magma mixing produced intimate hybridisation. The preservation of primitive crystal assemblages is probably due to the geological situation in which the Diego de Almagro complex emplaced, that favoured the formation of monogenetic volcanic centres rather than of a central volcanic edifice, thus limiting the residence of mafic magmas in the crust and their interaction with crustal partial melts.Le andesiti basaltiche appartenenti al complesso vulcanico Diego de Almagro (Ande Centrali, 24°S, 66°W) sono state emesse nel Miocene Superiore a ben 300 km verso E dall’arco attivo, nella Cordigliera Orientale, all’estremo orientale di una delle più importanti strutture trascorrenti trasversali andine, la Calama-Olocapato-El Toro. Le lave e le piroclastiti di questo complesso vulcanico conservano tracce della loro storia evolutiva sotto forma di xenocristalli e di popolazioni di cristalli in disequilibrio che coesistono grazie a processi di mixing di magmi a diversa composizione. Nelle Ande Centrali, la contaminazione crostale condiziona fortemente la composizione dei magmi che risalgono attraverso la spessa crosta continentale, mascherando le caratteristiche della sorgente mantellica. Per questo motivo, abbiamo ritenuto interessante effettuare uno studio di dettaglio della petrografia e della chimica dei minerali delle andesiti basaltiche di Diego de Almagro, allo scopo di identificare le popolazioni di cristalli in equilibrio con i magmi più primitivi. I risultati raccolti finora hanno mostrato che le andesiti basaltiche sono il prodotto di un processo di mescolamento di magma basaltico ed andesitico verificatosi durante la risalita del magma nella crosta, in condizioni pre-eruttive. Nel processo di mixing che ha prodotto le andesiti basaltiche la frazione di magma basaltico era prevalente in volume rispetto a quella di magma andesitico, e le proprietà fisicochimiche dei due magmi permisero la realizzazione di una avanzata ibridizzazione. L’associazione mineralogica primitiva si è potuta preservare grazie alla particolare situazione geologica del complesso Diego de Almagro, che favoriva la formazione di centri monogenetici piuttosto che lo sviluppo di vulcani centrali, limitando così lo stazionamento dei magmi basici nei serbatoi crostali e di conseguenza l’interazione con la crosta.Fil: Gioncada, Anna. Università degli Studi di Pisa; ItaliaFil: Hauster, Natalia. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Matteini, Massimo. Universidade do Brasília; BrasilFil: Mazzuoli, Roberto. Università degli Studi di Pisa; ItaliaFil: Omarini, Ricardo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentin

Tectosedimentary evolution of the Payogastilla Group and and its relation to Cenozoic volcanic arc, in the Calchaquí, Tonco and Amblayo valleys, Salta province, Argentina

Las características estratigráficas y sedimentológicas de los depósitos del Grupo Payogastilla son aspectos muy importantes a tener en cuenta para investigar la evolución tecto-sedimentaria de la cuenca de antepaís andino en el noroeste de la Argentina. El límite estratigráfico inferior del Grupo Payogastilla está marcado por una paraconcordancia con los depósitos de post-rift de la Formación Lumbrera (Subgrupo Santa Bárbara, Grupo Salta). El límite estratigrá- fico superior de la Formación Los Colorados, es paraconcordante y discordante; la subsidencia de la cuenca fue pareja entre ~35 a 21 Ma. En el Mioceno medio a superior, los depósitos de la Formación Angastaco, con espesores de 4550 m (río Calchaquí) y 1500 m (Tonco) reflejan una importante influencia tectónica, la que delimitó el depocentro de la cuenca de Angastaco, con un inicio en el valle El Tonco (>13,7 Ma) y posteriormente en el valle Calchaquí (~13 Ma). Con posterioridad a los ~13 Ma se habrían desarrollado incipientes barreras orográficas en el este (sierras Los Colorados y León Muerto), que durante el Mioceno superior (10 a 5 Ma) se habrían reactivado para formar cadenas orográficas importantes. Durante el Plioceno se habrían reactivado nuevamente los alzamientos tectónicos, generando sistemas fluviales entrelazados gravosos, con una marcada proveniencia desde el este. Los niveles de tobas intercalados en los depósitos de las formaciones Angastaco y Palo Pintado, muestran una clara signatura de arco indicando su proveniencia del arco activo a esos tiempos, con características que indican una componente cortical participante en sus magmas. Mientras que, los niveles piroclásticos intercalados en la Formación San Felipe, por su mayor carácter peraluminoso y sus menores contenidos en Na20 respecto a K20, que las ubican en el campo de los granitos tipo S, dando idea de componentes corticales distintas.The stratigraphic and sedimentological characteristics of Payogastilla Group deposits are very important to study tecto-sedimentary evolution of the Andean foreland basin in northwestern Argentina. The lower stratigraphic boundary of Payogastilla Group with the Lumbrera Formation (Santa Barbara Subgroup, Salta Group) deposits is a paraconformity. The upper stratigraphic boundary, the Colorados Formations is a paraconformity and a unconformity, the subsidence of the basin was uniform and the duration of the initial deposit was about ~35 to 21 Ma. During the middle to upper Miocene, represented by Angastaco Formation deposits, with a thickness of 4550 m (in Calchaquí river) and 1500 m (in Tonco) it took place a major tectonic influence, which delimited the basin depocenter in Angastaco basin. This event started in Tonco valley (>13.7 Ma) and later continued in Calchaquí valley (~13 Ma). Also in the ~13 Ma it have developed two orographic barriers (Los Colorados and León Muerto ranges), in the eastern, that during the Late Miocene (10-5 Ma) would have been reactivated to an important orographic chains form. During the Pliocene the tectonic uplifts would have reactivated, being registered as alluvial fans with a strong provenance from the east. Levels tuff deposits intercalated in Angastaco and Palo Pintado formations, show a clear signature of the arc indicating their origin of the arc active to those times with features that indicate a crustal component in their magmas participant. While pyroclastic levels intercalated in San Felipe Formation, with higher peraluminous character and lower Na20 K20 content regarding, which lie in the area of the type S granites, giving different cortical components idea.Fil: Galli, Claudia. Universidad Nacional de Salta; ArgentinaFil: Coira, Beatriz Lidia Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina. Universidad Nacional de Salta; ArgentinaFil: Matteini, Massimo. Universidade Do Brasilia; BrasilFil: Hauser, Natalia. Universidade Do Brasilia; Brasi

Combined U-Pb and Lu-Hf isotope analyses by laser ablation MC-ICP-MS : methodology and applications

O sistema isotópico Lutécio-Hafnio representa uma das ferramentas mais recentes e poderosas para estudos isotópicos e geocronológicos. Análises combinadas in situ de U-Pb e Lu-Hf sobre zircão pelo LA-MC-ICP-MS permitem caracterizar isotopicamente o magma onde ele cristalizou, fornecendo valiosas informações para estudos de proveniência de sedimento e de evolução crustal. Nesse trabalho descrevemos a sistemática de Lu-Hf pelo LA-MC-ICP-MS implantada no laboratório de Geocronologia da Universidade de Brasília e reportamos os resultados obtidos de repetidas análises de três padrões de zircão: GJ-1 = 0.282022 ± 11 (2SD, n=56), Temora 2 = 0.282693 ± 14 (2SD, n=25) and UQ-Z = 0.282127 ± 33 (2SD, n=11). Foi também caracterizada arazão isotópica 176Hf/177Hf(0.282352 ± 22, 2SD, n=14) de um zircão usado como padrão interno do laboratório. Como aplicação geológica, analisamos dois zircões complexos selecionados a partir de uma amostra de migmatito da Província de Borborema, NE do Brasil. Sobre a base dos dados U-Pb e Lu-Hf foram identificados em ambos os zircões dois eventos de cristalização. Um evento mais antigo de 2.05 Ga nos núcleos herdados, representa um evento magmático Paleoproterozoico bem conhecido na Província Borborema. Um segundo evento de ~ 575 Ma, reconhecido nas bordas, representa um evento magmático-metamórfico Neoproterozóico (Brasiliano). ________________________________________________________________________________________ ABSTRACTThe Lutetium-Hafnium isotopic system represents one of the most innovative and powerful tools for geochronology and isotopic studies. Combined U-Pb and Lu-Hf in situ analyses on zircon by LA-MC-ICP-MS permit to characterize isotopically the host magma from which it crystallized furnishing significant information for sediment provenance and crustal evolution studies. In this paper e describe the Lu-Hf systematic by LA-MC-ICP-MS developed in the laboratory of Geochronology of the University of Brasilia and report the results obtained by repeated analyses of 176Hf/177Hf isotopic ratio of three zircon standards: GJ-1 = 0.282022 ± 11 (n=56), Temora 2 = 0.282693 ± 14 (n=25) and UQZ = 0.282127 ± 33 (n=11). The 176Hf/177Hf ratio (0.282352 ± 22, n=14) of gem quality zircon used as in-house standard have been also characterized. As a geological application, we analyzed two complex zircons selected from a migmatitic rocks from the Borborema Province, NE Brazil. On the basis of U-Pb and Lu-Hf data, two main crystallization events have been identified in both studied zircons. An older event at ca. 2.05 Ga recognized in the inherited cores represents a well-characterized paleoproterozoic magmatic event that affected the whole Borborema Province. A second crystallization event at ~ 575 Ma, recognized at the rims, represents a Neoproterozoic (Brazilian) high grade metamorphic-magmatic event

U-Pb and Lu-Hf zircon geochronology of the Cañadón Asfalto Basin, Chubut, Argentina: Implications for the magmatic evolution in central Patagonia

The Cañadón Asfalto basin, central Chubut, Argentina, comprises a volcano-sedimentary sequence related to the opening of the Atlantic Ocean during Mesozoic times. The Lonco Trapial, Cañadón Asfalto and Cañadón Calcáreo formations are the main units related to the evolution of this basin. The Las Chacritas and Puesto Almada members are distinguished in the Cañadón Asfalto Formation. LA-HR-ICP-MS U-Pb and Lu-Hf data on zircon were obtained on these units. The Lonco Trapial Formation gave a weighted average age of 172.3±1.8 Ma. A pyroclastic level from the Las Chacritas Member gave a weighted average age of 168.2±2.2 Ma. Two U-Pb concordant ages of 160.3±1.7 Ma on a laminated tuffite and 158.3±1.3 Ma on a pyroclastic level were obtained for the Puesto Almada Member. Two maximum depositional ages constrain the sedimentary provenance areas for the basin: 1) A sample from the Sierra de la Manea range, where a controversial unit related either to the Cañadón Asfalto or to the Cañadón Calcáreo formation occurs, gave an age of 176.6±1.0 Ma. Two younger zircon crystals indicate that this unit may be related to the Cañadón Calcáreo Formation. 2) A sandstone with cross-stratification from the Puesto Almada Member gave a maximum depositional age of 173.6±6.4 Ma. In terms of U-Pb and Lu-Hf isotopes, two magmatic events are identified in central Patagonia: the Mamil Choique magmatic event characterized by negative εHf values around -5.0 and representing recycling during Permian times of Mesoproterozoic crust (TDM of ~1.5 Ga), and the Cañadón Asfalto magmatic event with negative (-8.2) to positive (+4) εHf values and Meso- to Neoproterozoic TDM between 1.5 and 0.8 Ga. The younger event is characterized by three main cycles: C1 related to the Lonco Trapial magmatism, C2 to the Las Chacritas volcanism, and C3 to the Puesto Almada volcanism. These cycles are related with Marifil, Chon Aike and El Quemado formations volcanics events of Patagonia and the Neuquén Basin during the Mesozoic.Fil: Hauser, Natalia. Universidade Do Brasilia. Instituto de Geociencias; BrasilFil: Cabaleri, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; ArgentinaFil: Gallego, Oscar Florencio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Monferran, Mateo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Silva Nieto, Diego Gonzalo. Secretaria de Industria y Mineria. Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales. Dirección de Geología Regional; ArgentinaFil: Armella, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; ArgentinaFil: Matteini, Massimo. Universidade Do Brasilia. Instituto de Geociencias; BrasilFil: Aparicio Gonzalez, Pamela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; ArgentinaFil: Pimentel, Marcio. Universidade Do Brasilia. Instituto de Geociencias; BrasilFil: Volkheimer, Wolfang. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Reimold, W. U.. Universität zu Berlin; Alemani

GWAS analysis of handgrip and lower body strength in older adults in the CHARGE consortium

Decline in muscle strength with aging is an important predictor of health trajectory in the elderly. Several factors, including genetics, are proposed contributors to variability in muscle strength. To identify genetic contributors to muscle strength, a meta-analysis of genomewide association studies of handgrip was conducted. Grip strength was measured using a handheld dynamometer in 27 581 individuals of European descent over 65 years of age from 14 cohort studies. Genomewide association analysis was conducted on ~2.7 million imputed and genotyped variants (SNPs). Replication of the most significant findings was conducted using data from 6393 individuals from three cohorts. GWAS of lower body strength was also characterized in a subset of cohorts. Two genomewide significant (P-value< 5 × 10−8) and 39 suggestive (P-value< 5 × 10−5) associations were observed from meta-analysis of the discovery cohorts. After meta-analysis with replication cohorts, genomewide significant association was observed for rs752045 on chromosome 8 (β = 0.47, SE = 0.08, P-value = 5.20 × 10−10). This SNP is mapped to an intergenic region and is located within an accessible chromatin region (DNase hypersensitivity site) in skeletal muscle myotubes differentiated from the human skeletal muscle myoblasts cell line. This locus alters a binding motif of the CCAAT/enhancer-binding protein-β (CEBPB) that is implicated in muscle repair mechanisms. GWAS of lower body strength did not yield significant results. A common genetic variant in a chromosomal region that regulates myotube differentiation and muscle repair may contribute to variability in grip strength in the elderly. Further studies are needed to uncover the mechanisms that link this genetic variant with muscle strength

Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness

Hand grip strength is a widely used proxy of muscular fitness, a marker of frailty, and predictor of a range of morbidities and all-cause mortality. To investigate the genetic determinants of variation in grip strength, we perform a large-scale genetic discovery analysis in a combined sample of 195,180 individuals and identify 16 loci associated with grip strength (P<5 x 10(-8)) in combined analyses. A number of these loci contain genes implicated in structure and function of skeletal muscle fibres (ACTG1), neuronal maintenance and signal transduction (PEX14, TGFA, SYT1), or monogenic syndromes with involvement of psychomotor impairment (PEX14, LRPPRC and KANSL1). Mendelian randomization analyses are consistent with a causal effect of higher genetically predicted grip strength on lower fracture risk. In conclusion, our findings provide new biological insight into the mechanistic underpinnings of grip strength and the causal role of muscular strength in age-related morbidities and mortality

Combined U-Pb and Lu-Hf isotope analyses by laser ablation MC-ICP-MS: methodology and applications

The Lutetium-Hafnium isotopic system represents one of the most innovative and powerful tools for geochronology and isotopic studies. Combined U-Pb and Lu-Hf in situ analyses on zircon by LA-MC-ICP-MS permit to characterize isotopically the host magma from which it crystallized furnishing significant information for sediment provenance and crustal evolution studies. In this paper e describe the Lu-Hf systematic by LA-MC-ICP-MS developed in the laboratory of Geochronology of the University of Brasilia and report the results obtained by repeated analyses of 176Hf/177Hf isotopic ratio of three zircon standards: GJ-1 = 0.282022 ± 11 (n=56), Temora 2 = 0.282693 ± 14 (n=25) and UQZ = 0.282127 ± 33 (n=11). The 176Hf/177Hf ratio (0.282352 ± 22, n=14) of gem quality zircon used as in-house standard have been also characterized. As a geological application, we analyzed two complex zircons selected from a migmatitic rocks from the Borborema Province, NE Brazil. On the basis of U-Pb and Lu-Hf data, two main crystallization events have been identified in both studied zircons. An older event at ca. 2.05 Ga recognized in the inherited cores represents a well-characterized paleoproterozoic magmatic event that affected the whole Borborema Province. A second crystallization event at ~ 575 Ma, recognized at the rims, represents a Neoproterozoic (Brazilian) high grade metamorphic-magmatic event.O sistema isotópico Lutécio-Hafnio representa uma das ferramentas mais recentes e poderosas para estudos isotópicos e geocronológicos. Análises combinadas in situ de U-Pb e Lu-Hf sobre zircão pelo LA-MC-ICP-MS permitem caracterizar iso-topicamente o magma onde ele cristalizou, fornecendo valiosas informações para estudos de proveniência de sedimento e de evolução crustal. Nesse trabalho descrevemos a sistemática de Lu-Hf pelo LA-MC-ICP-MS implantada no laboratório de Geocronologia da Universidade de Brasília e reportamos os resultados obtidos de repetidas análises de três padrões de zircão: GJ-1 = 0.282022 ± 11 (2SD, n=56), Temora 2 = 0.282693 ± 14 (2SD, n=25) and UQ-Z = 0.282127 ± 33 (2SD, n=11). Foi também caracterizada arazão isotópica 176Hf/177Hf(0.282352 ± 22, 2SD, n=14) de um zircão usado como padrão interno do laboratório. Como aplicação geológica, analisamos dois zircões complexos selecionados a partir de uma amostra de migmatito da Província de Borborema, NE do Brasil. Sobre a base dos dados U-Pb e Lu-Hf foram identificados em ambos os zircões dois eventos de cristalização. Um evento mais antigo de 2.05 Ga nos núcleos herdados, representa um evento magmático Paleoproterozoico bem conhecido na Província Borborema. Um segundo evento de ~ 575 Ma, reconhecido nas bordas, representa um evento magmático-metamórfico Neoproterozóico (Brasiliano)