Abstract Palaeozoic stromatoporoids, throughout their 100-million + year history (Middle Ordovician to Late Devonian and rare Carboniferous), are better preserved than originally aragonite molluscs, but less well-preserved low magnesium-calcite brachiopods, bryozoans, trilobites corals. However, the original mineralogy of stromatoporoids remains unresolved, details diagenesis patchy. This study...

le gisement de pallieres(1)qui se situe dans le s. e. du massif central francais, est frome de quatre niveaux plombo-zinciferes stratiformes, repartis dans 200 m. d'epaisseur de dolomie hettangienne, la genese de ce gisement est le sujet de discussion, il y a longtemps, l. calembebt (1957) l'avait considere tin gisement hydrothermal; mais pour a. bernarti (1958) c'est un gisement...

Stromatolites have been widely reported from the Archean and Paleoproterozoic successions worldwide, they could represent one of oldest life forms on Earth. Of these, a group small stromatolites occur as microdigitate low-relief columns, are also conspicuous in field. However, biogenicity these (MDSs) has long disputed due to abundance radial-fibrous texture lack convincing microfossils. New ex...

Faunal analysis of modern (Benguela upwelling system, Namibia) and ancient (upper Cretaceous, Israel) sedimentary records rich in organic matter, biogenic silica, carbonate, and phosphate indicates that, contrary to stereotypes of upwelling systems as dead zones, macrobenthic communities are present but highly variable. Biofacies vary with distance from the upwelling core and as a function of b...

introduction the shahrestanak mn deposit is located in southern qom province, 12 km southwest of the city of kahak. based on geological-structural divisions of iran, the deposit belongs to central volcanic belt or urumieh-dokhtar zone. the venarch deposit is one the most important known manganese deposits in iran. the sharestanak and venarch deposits are spatially and temporally related to each...

This study documents a convincing correlation of stable oxygen isotopic variation extracted from Paleocene aged bulk sediment carbonates of the Scaglia Rossa formation in the Apennines Mountains of Italy with the variations found in Pacific, benthic organism derived carbonates presented by Zachos et al. (2005). Using δO variation as a proxy for sea-level change, a first-order correlation can al...

This report describes the results of a comprehensive surficial geologic mapping effort undertaken to support the development of a series of relative flood hazard maps of the Ivanpah Valley area, Clark County, Nevada. The study area spans approximately 1030 km2 (398 mi2) and is defined by all of three and part of one internally drained basins between Las Vegas and Primm, Nevada. The proximity of...