Composición isotópica del sulfato de las evaporitas Messinienses de la cuenca del Piamonte (Italia)

The Piedmont basin (NW Italy) records a Messinian Salinity Crisis (MSC) succession including a selenite gypsum deposit assigned to the Primary Lower Gypsum (PLG, MSC stage 1). Strontium isotope ratios are in the range of the PLG deposits of the Mediterranean area. Sulfate isotope compositions of vertically oriented selenite gypsum beds, in the lower part of the succession, are similar to those reported in other PLG deposits. However, flattened branching selenite cones in the upper part show higher isotope compositions, mainly in δ34S values, suggesting intense BSR conditions, stronger than reported in other PLG deposits. We interpret this chemical shift during deposition of the upper part of the PLG as the result of increased marine restriction assisted by the marginal position of this basin in the Adriatic Gulf during the Apennine and Alpine upliftsLa cuenca del Piamonte (NW Italia) contiene una serie Messiniense que incluye una unidad de yeso selenítico atribuida al PLG (MSC estadio 1). La isotopía del estroncio confirma esta asignación. La isotopía del sulfato de los yesos seleníticos de desarrollo vertical de la parte inferior de la serie es comparable a la de otras series PLG del Mediterráneo. Sin embargo, los conos de desarrollo horizontal de la parte superior de la serie muestran composiciones isotópicas mayores, especialmente en δ34S, sugiriendo una intensa actividad bacteriana (BSR) no observada en otros depósitos PLG. Interpretamos esta diferencia como resultado de mayores condiciones de restricción marina de la cuenca del Piamonte debidas a la posición marginal de esta cuenca en el Golfo Adriático durante el levantamiento de los Apeninos y los Alpe

Exploring the hydrochemical evolution of brines leading to sylvite precipitation in ancient evaporite basins.

Sylvite is a very common mineral in ancient evaporite deposits. Due to the absence of current deposits, the natural geochemical mechanism/s for synsedimentary sylvite precipitation and accumulation are not well understood. Numerous sylvite deposits or portions of them have been described as a result of diagenesis (i.e. Sergipe subbasin, Brasil). However, a number of deposits have been described as synsdimentary or being formed during primary evaporite deposition. It is the last group of deposits that can be studied to better understand the hydrochemical processes taking place in the brine at the onset of sylvite precipitation. The Salt IV sylvite beds from the Mulhouse potash basin, Alsace (France) have been described as synsedimentary in origin (LOWENSTEIN and SPENCER, 1990; CENDON et al., 2008). While sylvite in itself does not contain fluid inclusions viable for micro analysis, primary textures in neighboring halite are used as a proxy to understand brine evolution. Two halite-sylvite cycles from the B1 and B2 layers of the potash lower seam were selected. These exhibited clear primary halite crystal textures with sylvite adapting to an irregular halite sedimentary surface and finishing with a flat surface. The nine halite samples, selected at centimeter scale, provided close to 100 single fluid inclusion analyses, representing both the transition towards sylvite precipitation and the post sylvite precipitation. The fluid inclusion analyses revealed strong fluctuations in K concentration, well over the analytical error (<10%). These variations, in the same halite crystal, seem aligned in growth bands, with fluid inclusions within a certain growth band showing practically identical K concentrations, while neighboring bands exhibit a different concentration. Overall, the closer we are from a sylvite layer the higher K concentrations are. However, strong fluctuations continue when growth bands are compared. This pattern shows cycles of increasing K concentration along parallel growth bands with sharp falls followed by the initiation of a new increasing trend. The small “growth band” scale of the K concentration variations, suggests very sensitive processes within the brine with potential environmental changes (i.e. seasonal variations, day-night temperature fluctuations cycles) leading towards the final mass precipitation of a sylvite layer

Mitochondrial DNA Variation, but Not Nuclear DNA, Sharply Divides Morphologically Identical Chameleons along an Ancient Geographic Barrier

The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Formaciones salinas de las cuencas triásicas en la Península Ibérica: caracterización petrológica y geoquímica.

[ES] Se estudian muestras de sal y anhidrita triásicas procedentes de sondeos y, en menor medida, de algunos afloramientos y galerías de mina. Las características texturales y de litofacies indican la existencia de procesos de recristalización en la halita con pérdida de las texturas primarias de tipo hopper y chevron, que son en parte sinsedimentarios y en parte de diagénesis de enterramiento. Adicionalmente, en las zonas diapirizadas la recristalización es más intensa y la brechificación frecuente. Los contenidos en bromo de la halita y las composiciones isotópicas de las anhidritas en las diferentes formaciones estudiadas son relativamente homogéneos, indicando el origen marino de las salmueras y la estabilidad en la alimentación oceánica, a pesar del carácter generalizado de transición de los medios sedimentarios. De acuerdo con estas texturas y contenidos elementales de la halita, y por comparación con los encontrados en otras cuencas triásicas europeas y del N de África, las condiciones de sedimentación del conjunto de formaciones salinas triásicas de la Península Ibérica parecen muy uniformes, propias de cuencas poco profundas en las que no se pone de manifiesto, desde el punto de vista geoquimico, una Influencia de aguas continentales. Las importantes acumulaciones salinas y de sulfatos registradas en estas cuencas son los mejores indicadores de la fuerte subsidencia generada por el proceso de rifting triásico.[EN] Triassic salt and anhydrite samples coming from boreholes and in mínor degree from mine galleries and outcrops are studied. Lithofacies and textural characteristics of halite suggest the existence of recrystallization processes leading to the loss of primary features such as hopper and chevrons, which are in part synsedimentary (early diagenetic) and in part of deep burial origin. Moreover, in the diapiric zones recrystallization becomes severe and brecciation appears very frequently. Both bromine content of balite and isotopic composition of anhydrite are relatively homogeneous in the various basins studied, thus proving the marine origin of mother brines and a stable inflow from the ocean, despite the fact that sedimentation took place in generallized transitional environments. According to these textures and geochemical contents, and in comparison with those exhibited in other Triassic basins of Europe and North África, it can be stated that conditions governing salt precipitation in the Iberian Peninsula during Triassic times were rather uniform and corresponded to shallow basins in wich the possible influence of continental water can not be proved from the geochemical point of view. Important chloride and sulphate accumulations recorded in these basins may be held as the best indicator of continuous subsidence controlled by the Triassic rifting.Este trabajo se ha realizado en el marco del proyecto DGICYT PB9O-0485. Las muestras de los dos sondeos Bobalar fueron cedidas por ENIEP5A en 1987. Los datos de bromo correspondientes a los sondeos de la zona diapírica Cántabro-Navarra se incluyen con la autorización de ENRESA. Agradecemos la colaboración prestada por la dirección y el personal técnico de los Servicios Científico-Técnicos de la Universidad deBarcelona.Peer reviewe

Hydrochemical model of glauberíte-halite sedimentation: PURASAL borehole, Zaragoza Gypsum Fm. (Lower Miocene, Ebro Basin)

The geochemical study of halite samples belonging to PURASAL borehole (Zaragoza Gypsum Fm., non-marine Lower Miocene, Ebro Basin, Spain) shows low contents for Br, Mg and l<. The study of fluid inclusions (Cryo-SEM -EDS method) of these samples reveals very low contents of Kand S04 in the brines, and contents of Ca and Mg that are below the detection limit. The amount of S04 is significant only in a few halite samples associated with glauberite beds. These data agree with the mineral paragenesis (gypsum/anhydrite, glauberite, thenardite (?) and halite) where no Mg and/or l< minerals are observed in contrast to what occurs in other sodium sulphate deposits of Tertiary age in Spain which are characterized by the presence of polyhalite and magnesit

Strontium geochemistry in the Messinian gypsum of the San Miguel de Salinas basin (Alicante, SE Spain)

The Sr contents in the selenitic gypsum deposit of the San Miguel de Salinas basin (Alicante, SE Spain) are related to the sedim entary facies, that is to say, to the p etrological characteristics of the gypsum layers and their paleogeographical position in the basin. The selenitic gypsum facies corresponding to more central areas of the basin form thick beds and show relatively lo w and homogeneous contents. The selenitic gypsum facies corresponding to more marginal zones form thin beds and show higher and more disperse Sr contents

Fluid inclusions composition in halite from Biurrún borehole (Navarra Potash basin)

The solute concentration of fluid inclusions in halite samples have been analyzed by X-Ray microanalysis (Cryo-SEM-EDS). The results together with the mineral sequence are useful to describe the evolution of the Priabonian basin of Navarra. Thus, a lower salt unit (sal de muro) formed in a restricted basin with seawater recharge. Later, the basin closed to sea and evolved with decreasing volume and stratified brine to the deposition of potash salts. Finally, an upper salt unit (sal d e techo) formed in a continental lake without seawater influenc

Large gypsum nodules in the Paleogene and Neogene evaporites of Spain: distribution and palaeogeographic significance

Gypsiferous units occur along the margins of some Paleogene and Neogene basins in Spain. These units accumulated in shallow saline lakes of low ionic concentration. Other gypsiferous facies constitute outer rings of the thick, highly-saline evaporite formations that occupy the central parts of the basins. In some of these gypsum units and rings, large nodules (from 0.5 m to several metres across) of secondary gypsum that originated as replacive or displacive nodular anhydrite are present. Although these occurrences usually show a stratiform arrangement, vertical geometries are observed locally, suggesting ascending circulation of anhydritizing flows. The common characteristics of the large gypsum nodules in the various occurrences indicate that the precursor anhydrite formed in burial conditions from shallow to moderate depths. A few occurrences of large, secondary gypsum nodules in the gypsum units are linked to deep faults or diapiric structures

Zechstein saline brines in Poland, evidence of overturned anoxic ocean during the Late Permian mass extinction event.

Bromine concentrations in halite, sulfate isotopes (delta S-34 and delta O-18), and major ion concentrations in primary fluid inclusions from three boreholes in the Late Permian Zechstein evaporites have revealed sharp variations in marine derived brines within the Polish sector of the European Southern Permian Basin. The base of the Older Halite (Na2), during the latest Permian, registers a change from sulfate-rich brines, similar in composition to modern evaporated seawater, to sulfate-depleted brines (calcium-rich). This change coincides with a drop in delta S-34 to values close to +9 parts per thousand, not observed in delta O-18 counterparts. Opposite isotope (delta S-34-delta O-18) trends through the Na2 unit cannot be explained by changes in restriction conditions. We propose that the change to sulfate-depleted (calcium-rich) brines during halite deposition of the PZ2 (Stassfurt) cycle is related to the overturn of anoxic sulfidic deep-waters from the Panthalassa stratified superocean coinciding in time with the Permian-Triassic mass extinction event. The reconstruction of chemical changes in brines reveals two major evaporite sequences of increasing concentration that do not match the classic lithostratigraphic cycles. The first evaporite sequence (PZES-1) contain the evaporite units of the PZ1 (Werra) cycle, the PZ2 (Stassfurt) cycle, the Main Anhydrite (A3), and the base of the Younger Halite (Na3) of the PZ3 (Leine) cycle. The second evaporite sequence (PZES-2) is represented by almost the entire Na3 unit and the PZ4 (Aller) cycle. (C) 2011 Elsevier B.V. All rights reserved