Environmental controls and facies architecture of a jurassic carbonate episode La Manga Formation), Mendoza Province, Neuquén Basin

La Manga Formation is a vast carbonate system developed in the Neuquén Basin. The age is based in ammonite faunas, ranging from Early Callovian (Bodenbenderi-Proximum Zone) to Middle Oxfordian (Cordatum Standard Zone to Transversarium Standard Zone, and probably to the lower part of the Bifurcatus Standard Zone). A stratigraphical and sedimentological analysis, in the outcrops exposed in the south of Mendoza province, enabled the recognition of five facies associations of a carbonate ramp corresponding to (1) distal outer ramp, (2) proximal outer to distal middle ramp, (3) proximal middle ramp, (4) inner ramp deposits (shoreface, shoal, patch reef, shallow subtidal lagoon and tidal flat) and (5) paleokarstic facies. These facies correspond to homoclinal to distally steepened carbonate ramp. The facies associations are included into three third-order depositional sequences (DS-1, DS-2, DS-3) represented by transgressive and highstand systems tracts with sequence boundaries of regional character. Different controlling factors can be recognised in the deposition of this unit. The abrupt changes of facies, as well as paleokarst and epikarst discontinuity surfaces in the successions provide important evidence in terms of depositional environment and vertical evolution of the carbonate ramp. Facies patterns are variable across the outcrop area and vertically through time because of a combination of ramp morphology, siliciclastic supply, sea level changes and tectonic effects. In the southern sections, siliciclastic influx influenced the deposition of proximal middle ramp facies later overlain by scleractinian patch reefs which grew up throughout progressive stages from aggradational to progradational facies in response to climate controls and nutrient levels influence. In northern outcrops, tectonic controls affected the ramp topography and influenced the development of distal deep marine facies. Shallow subtidal and peritidal cycles indicate a combination of allocyclic and autocyclic processes controlling accommodation space and sediment accumulation.Fil: Palma, Ricardo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Bressan, Graciela Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Riccardi, Alberto Carlos. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: López Gómez, José. Universidad Complutense de Madrid; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Martín Chivelet, Javier. Consejo Superior de Investigaciones Científicas; España. Universidad Complutense de Madrid; Españ

Lessons from the Past: Sponges and the Geological Record

Sponges have been a major part of marine ecosystems, in both shallow and deep water, from the time of the earliest animal communities. The great shifts in climate that have occurred over the past 541 million years have affected all organisms, including sponges. Although patchy knowledge of the sponge fossil record hinders recognition of trends, some general patterns are apparent. Shallow-water siliceous sponges were severely affected by glacial intervals, whereas deeper-water siliceous sponges appear to have flourished during these times. Some groups of hypercalcified sponges (such as stromatoporoids) were abundant during times of global warming and high sea level, but other groups (archaeocyathans and sphinctozoans) had their acme during times of low sea level and relatively cool climate. Overall, sponge diversity appears to have been controlled more by sea level than by climate: large-scale sponge biotas occurred at times of high sea level, when there were large areas of shallow sea.Fil: Muir, Lucy. National Museum Wales; Reino UnidoFil: Botting, Joseph P.. National Museum Wales; Reino Unido. Nanjing Institute Of Geology And Palaeontology; ChinaFil: Beresi, Matilde Sylvia. 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; Argentin