1,358 research outputs found
Fractionation by compositional magma splitting: An example from Cerro Munro, Argentina
The manuscript has been benefited from valuable suggestions from Mattia Pistone and Jiri Zak. This work is supported by IBERCRUST project (PGC2018-096534-B-I00). C. R. is grateful for her AUIP grants (Asociacion Universitaria Iberoamericana de Postgrado) for both stays at the Universidad Nacional de La Plata (Argentina), during 2015 and 2018, and for her postdoctoral contract from the University of Huelva (under the Estrategia Politica Cientifica de la UHU 2016/2017). This is the IBERSIMS publication n.85. JM is funded by the MINECO grant CGL2017-84901-C2-P1.The Paleocene-Eocene Cerro Munro pluton, to the east of the North Patagonian Batholith (NPB), is a tonalitic
intrusion emplaced as a shallow, small, sub-circular tonalite-granodiorite body hosting abundant co-magmatic
mafic microgranular enclaves (MME). Besides, the intrusive body is crosscut by radial porphyritic dikes and
has been related to andesitic, dacitic and rhyolitic dikes, lava flows and ignimbrites cropping out at neighboring
areas. Magmatic contacts between MME and host tonalites, together with their common geochemical features,
suggest derivation from a common parental magma, although short-range mineralogical and geochemical differences
point to an early crystallization of MME (chilled margins) at the sidewalls of ascent conduits or at
shallow reservoirs. The established thermal gradient and the advance of the solidification front were responsible
for the presence of the mafic microgranular and tonalitic subsystems and, in a continuous process, promoted the
water saturation and the second boiling that finally account for the segregation of a water rich highly differentiated
residual liquid. Hbl-Pl cumulate textures observed in the tonalites and mafic enclaves, as well as
incompatible element-enriched rhyolitic melts record the results of this in-situ differentiation process. U–Pb
zircon ages obtained from tonalites (57.1 ± 1.4 Ma), dacitic (55.4 ± 0.6 Ma) and rhyolitic (54.1 ± 0.7 Ma) dikes
constrain an age of around 54 Ma for the final consolidation of the tonalitic magma and the crystallization of the
expelled highly differentiated melts. This age coincides with the deposition of dacitic volcanic and volcanoclastic
deposits to the north of the Cerro Munro pluton, which suggests that the fractionation process led to the extrusion
of segregated melts, favored by extension, uplift and exhumation of an active rift tectonic setting.IBERCRUST project PGC2018-096534-B-I00AUIP grants (Asociacion Universitaria Iberoamericana de Postgrado)University of HuelvaMINECO CGL2017-84901-C2-P
Paleogene evolution of the External Rif Zone (Morocco) and comparison with other western Tethyan margins
The Paleogene evolution of theNWmargin of the African Plate (Western External Rif Zone)was studied by means of
multidisciplinary analyses of twenty-one stratigraphic logs, including tectofacies recognition, petro-mineralogical
results, and thicknesses analysis. Four stratigraphic intervals were recognized separated by three unconformities
coarsely aligned with the Cretaceous–Paleogene, Eocene–Oligocene and Oligocene–Miocene boundaries, respectively.
Tectofacies appear from the late Ypresian being more frequents from the Oligocene as the tectonic activity increases.
The petrology of detrital suites indicates recycled orogen-derived sediments, with quartz supplied from
metamorphic rocks of the Atlas orogen and/or the African craton. On the basis ofMesozoic claymineral assemblages
reported in the literature, the clay mineralogy of mudstones suggests upper Jurassic to upper Cretaceous terrains
from the Internal Intrarif as the main source area of the Paleocene–Eocene successions, with sediment provenance
reversion during the Oligocene and additional contribution of Paleocene to lower Eocene suites. The different displacement
capability of the identified aluminic-magnesic claymineralogy enabled to deduce the relative proximity
of the source area. These findings point out a complex sedimentary evolution characterized by a mixture of different
lithotypes dating back to upper Jurassic. X-ray parameters helped to identify evidences of synsedimentary tectonics
overprinting the inheritedmineralogy during some periods with weak burial diagenesis at most. During the Paleogene
a foreland basin is formed mainly in theMesorif and Prerif sub-domains. This foredeep was represented by two
‘sub-geosynclines’ separated by a relative bulge located in the ExternalMesorif. The Internal Intrarif could represent
the relative orogenic front, advancing on the External Intrarif. The Eocene forebulge was located in the Ridges Domain,
while the Gharb Basin was the backbulge of the system. During the Oligocene the depocentral area migrated
southward and a homogeneization of thicknesses took also place in thewholemargin. In this newconfiguration, the
foredeep would be located in the External Mesorif (previously a relative bulge) while the Ridges Domain and the
Gharb Basin continued to act as the systemforebulge and backbulge, respectively. A comparisonwith the Paleogene
evolution of otherwestern Tethys externalmargins (Betic Chain, Tunisian Tell, SicilianMaghrebids, and Apennines)
has revealed more similarities than differences. The effects of the Eo-Alpine tectonics are recognized everywhere
even if they decrease both from N to S, and fromWto E in the different considered margins. The evolution of the
compared margins shows a common pre-foredeed (Paleocene-Eocene) and beginning of foredeep (Oligocene)
stages in the foreland basins.PID2020-114381GB-I00
research project (Spanish Ministry of Education and Science)
Compressional behavior of the aragonite-structure carbonates to 6 GPa
Supplementary Information The online version contains supplemen-
tary material available at https://doi.org/10.1007/s00269-023-01237-6.The behaviors of aragonite (CaCO3
), strontianite (SrCO3
), cerussite (PbCO3
), and witherite (BaCO3
) at increasing pressure have been studied up to 6 GPa using density functional theory with plane waves. A parallelism of the orthorhombic carbonates with the closed-packed AsNi structure is considered in our analysis, being the CO2−3
groups not centered in the interstice of the octahedron. The decomposition of the unit-cell volume into atomic contributions using the Quantum Theory of Atoms in Molecules has allowed the analysis of the bulk modulus in atomic contributions. The bulk, axes, interatomic distances, and atomic compressibilities are calculated. The largest compression is on the c crystallographic axis, and the c linear modulus has a linear function with the mineral bulk modulus (K0
). Many of the interatomic distances moduli of the alkaline earth (AE) carbonates show linear functions with the bulk modulus; however, the whole series (including cerussite) only gives linear functions when K0
is related either with the CC distances modulus or the modulus of the distances of the C to the faces of the octahedron perpendicular to c. These last distances are the projections of the Metal–Oxygen (MO) distances to the center of the octahedron. K0AE
carbonates also show linear functions with the atomic moduli of their cations. However, the whole series show a linear relation with the atomic modulus of C atoms. Therefore, the whole series highlight the importance of the C atoms and their interactions in the mechanism of compression of the orthorhombic carbonate series.Spanish MCINN and European FEDER Grants FIS2016-77692-C2.
2PCIN-2017-098Junta de AndalucÃa for
the RNM-264-363 and RNM-264-1897 PAI-Grant
Diamond forms during low pressure serpentinisation of oceanic lithosphere
Diamond is commonly regarded as an indicator of ultra-high pressure conditions in
Earth System Science. This canonical view is challenged by recent data and interpretations
that suggest metastable growth of diamond in low pressure environments.
One such environment is serpentinisation of oceanic lithosphere, which produces
highly reduced CH4-bearing fluids after olivine alteration by reaction with infiltrating
fluids. Here we report the first ever observed in situ diamond within olivine-hosted,
CH4-rich fluid inclusions from low pressure oceanic gabbro and chromitite samples
from the Moa-Baracoa ophiolitic massif, eastern Cuba. Diamond is encapsulated in
voids below the polished mineral surface forming a typical serpentinisation array,
with methane, serpentine and magnetite, providing definitive evidence for its metastable
growth upon low temperature and low pressure alteration of oceanic lithosphere
and super-reduction of infiltrated fluids. Thermodynamic modelling of the observed solid and fluid assemblage at
a reference P-T point appropriate for serpentinisation (350 °C and 100 MPa) is consistent with extreme reduction of the fluid
to logfO2 (MPa) = −45.3 (ΔlogfO2[Iron-Magnetite] = −6.5). These findings imply that the formation of metastable diamond at
low pressure in serpentinised olivine is a widespread process in modern and ancient oceanic lithosphere, questioning
a generalised ultra-high pressure origin for ophiolitic diamond.European Union (EU)Spanish Projects
CGL2015-65824
RTI2018-099157-A-I00
PID2019-105625RB-C21
A.RNM.186.UGR18Spanish Government
RYC-2015-17596Mexican research program CONACYT-Ciencia Basica
A1-S-14574Mexican research program UNAM-PAPIIT
IA-10141
Origin of the biphase nature and surface roughness of biogenic calcite secreted by the giant barnacle Austromegabalanus psittacus
The calcite grains forming the wall plates of the giant barnacle Austramegabalanus psittacus have
a distinctive surface roughness made of variously sized crystalline nanoprotrusions covered by
extremely thin amorphous pellicles. This biphase (crystalline-amorphous) structure also penetrates
through the crystal’s interiors, forming a web-like structure. Nanoprotrusions very frequently
elongate following directions related to the crystallographic structure of calcite, in particular,
the directions, which are the strongest periodic bond chains (PBCs) in calcite. We propose
that the formation of elongated nanoprotrusions happens during the crystallization of calcite from
a precursor amorphous calcium carbonate (ACC). This is because biomolecules integrated within the
ACC are expelled from such PBCs due to the force of crystallization, with the consequent formation of
uninterrupted crystalline nanorods. Expelled biomolecules accumulate in adjacent regions, thereby
stabilizing small pellicle-like volumes of ACC. With growth, such pellicles become occluded within
the crystal. In summary, the surface roughness of the biomineral surface reflects the complex shape
of the crystallization front, and the biphase structure provides evidence for crystallization from an
amorphous precursor. The surface roughness is generally explained as resulting from the attachment
of ACC particles to the crystal surface, which later crystallised in concordance with the crystal lattice.
If this was the case, the nanoprotrusions do not reflect the size and shape of any precursor particle.
Accordingly, the particle attachment model for biomineral formation should seek new evidence.Instituto de Salud Carlos III
Spanish Government
CGL2017-85118-P
CGL2015-64683-PUnidad Cientifica de Excelencia of the University of Granada
UCE-PP2016-05Junta de AndalucÃa
RNM363ANID-Chile
FONDECYT 1140938
PCI ANID REDES 170106
PIA ANID ANILLOS ACT17203
Crystal Growth of Inorganic and Biomediated Carbonates and Phosphates
In this chapter, we describe similar crystal growth features in inorganic and biogenic carbonates and phosphates formed in natural environments and in laboratory experiments. We focus on the importance of the kinetics on the crystal habit of carbonates and phosphates precipitated in biological and abiotic systems. We also discuss the influence of the nature and composition of the precipitation medium, as well as the structural control on crystal habit of Ca-Mg carbonates
EstadÃstica Básica con R y R-Commander
Los objetivos docentes se centran en introducir a los alumnos en los conceptos básicos de la EstadÃstica Descriptiva y la Inferencia y en la resolución, a través del software estadÃstico R, de problemas de análisis de datos y cálculo de probabilidades. En concreto nos centramos en análisis exploratorio de una y dos variables, distribuciones de probabilidades, inferencia en una y dos poblaciones y análisis de la varianza unifactorialUniversidad de Cádi
2M1 phlogopite–muscovite series minerals at increasing pressure to 9 GPa. I Atomic volumes and compressibilities
Open Access funding provided thanks to the CRUE-CSIC
agreement with Springer Nature.
Authors are thankful to Andalusian project
P18-RT-3786 for financial support, and to the Computational Centers
of the University of Granada and CSIC for computational facilities.Muscovite (Ms) and phlogopite (Phl) series mineral is studied in the 2M1 polytype and modeled by the substitution of three Mg2+ cations in the three octahedral sites of Phl [KMg3(Si3Al)O10(OH)2] by two Al3+ and one vacancy, increasing the substitution up to reach the Ms [KAl2□(Si3Al)O10(OH)2]. The series was computationally examined at DFT using Quantum ESPRESSO, as a function of pressure from − 3 to 9 GPa. Crystal structure is calculated, and cell parameters, and geometry of atomic groups agree with experimental values. OH in the Mg2+ octahedrons are approximately perpendicular to the (001) plane, meanwhile when they are in Al3+, octahedral groups are approximately parallel to this plane. From Quantum Theory of Atoms in Molecules, the atomic basins are calculated as a function of the pressure, K+ and basal O show the largest volumes. The bulk excess volume (Vxs) and the excess atomic volumes are analyzed as a function of the composition and the pressure. K+, basal and apical O Vxs show a behavior similar to the bulk Vxs as a function of the composition, keeping qualitatively this behavior as a function of pressure; substituent atoms do not show a Vxs behavior similar to the bulk and their effect consequently is mostly translated to atoms in the interlayer space. Atomic compressibilities are also calculated. Atomic compressibilities are separated in the different sheets of the crystal cell. Atomic moduli of K and basal O are the lowest and the ones behaving as the bulk modulus of the series. The atomic bulk modulus of the H’s is different depending of their position with respect to the (001) plane.CRUE-CSICAndalusian project
P18-RT-378
Optimization of analytical methods for the assessment of the quality of fats and oils used in continuous deep fat frying
La aplicabilidad, repetibilidad y capacidad de diferentes métodos de análisis para discriminar muestras de aceites con diferentes grados de oxidación fueron evaluadas mediante aceites recogidos en procesos de fritura en continuo en varias empresas españolas. El objetivo de este trabajo fue encontrar métodos complementarios a la determinación del Ãndice de acidez para el control de calidad rutinario de los aceites de fritura empleados en estas empresas. La optimización de la determinación de la constante dieléctrica conllevó una clara mejora de la variabilidad. No obstante, excepto en el caso del Ãndice del ATB, el resto de métodos ensayados mostraron una menor variabilidad. La determinación del Ãndice del ATB fue descartada ya que su sensibilidad fue insuficiente para discriminar entre aceites con diferente grado de oxidación. Los diferentes parámetros de alteración determinados en los aceites de fritura mostraron correlaciones significativas entre el Ãndice de acidez y varios parámetros de oxidación diferentes, como la constante dieléctrica, el Ãndice de p-anisidina, la absorción al ultravioleta y el contenido en polÃmeros de los triacilgliceroles. El Ãndice de acidez solo evalúa la alteración hidrolÃtica, por lo que estos parámetros aportan información complementaria al evaluar la alteración termooxidativa
Educational reforms competence-based approach: a comparative view
Grupo de Investigación FORCE (Formación Centrada en la Escuela) Universidad de Granad
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