Search results for "Sedimentary"

Sedimentary and diagenetic markers of the restriction in a marine basin: the Lorca Basin (SE Spain) during the Messinian

1998

Abstract The Lorca Basin (southeastern Spain) is part of a chain of small marginal Neogene basins located in the structurally active Betic area. The Upper Miocene (Messinian) sequence is composed of a thick diatomite-bearing series (Tripoli Unit) overlain by the Main Evaporites, analogous to the classical succession that records the main events during the Salinity Crisis in the Mediterranean region. The shallow restricted conditions of this region amplified the sedimentary responses to local and global forcings. An integrated approach using sedimentology, micropalaeontology, stable isotope geochemistry and organic geochemistry has been applied to the Tortonian/Messinian succession of the Lo…

Evidence of the Zanclean megaflood in the eastern Mediterranean Basin

2018

A. Micallef et. al.

Geochemical and Petrographic Characterization of Marine-Continental Transitional Facies Shale (Qilian Basin, China): Origin of Organic Matter Input, …

2021

This study, for the first time, investigates the source, keroger pattern, evolution degree, sedimentary environment, and evaluates the hydrocarbon generating ability of marine-continental transitional facies shale from the Ebao area of the Qilian Basin in western China. The organic-rich shales of the marine-continental transitional facies were subjected to total organic carbon (TOC), rock pyrolysis, the biomarkers and kerogen microscopy analyses. The kerogen microscopy analyses indicated that the sample from ZK001 well and ZK2002 well had a mass of vitrinite and small number of exinite, so kerogen type was mainly humic. According to vitrinite reflectance, the organic matter was in the stage…

Las ramblas valencianas: algunos aspectos de hidrología, geomorfología y sedimentología

1987

Tracing 2000 Years at the Source of the Douix, Côte-d’Or, France: Water, Offerings, and Recurrence

2019

The Source of the Douix in Châtillon-sur-Seine, France, has been visited by local inhabitants for over 2000 years and served as a watery focal point for the ritual deposition of various types of offerings. While water deposits are by no means uncommon across Europe, the continued use of a single space over multiple millennia is. An examination of the preserved offerings at the Douix indicate there are three phases of depositional activity: late Hallstatt to early La Tène periods, late La Tène to Gallo-Roman periods, and the early modern period. Despite being separated by hundreds of years there are similarities across depositional phases including the importance of modified metallic objects…

Taphonomic sequences—A new tool for sequence stratigraphy

2002

The Middle-Upper Jurassic boundary in western Europe is characterized by extensive condensed sections containing authigenic minerals together with abundant and varied fossils, both reworked and not reworked. We have analyzed ammonite shells and chronologically ordered taphonomic events in a taphonomic sequence extending from the time the dead organism settled on the seafloor to the time it became permanently incorporated in the sediment. Three types of taphonomic sequence are recognized; they are characteristic of (1) sedimentation in depositional environments having little and only occasional hydrodynamic activity (coinciding with periods of increasing accommodation), (2) sedimentation dur…

Anthropogenic units fingerprinted by REE in archaeological stratigraphy: Mas d'Is (Spain) case

2013

Abstract On occasions, archaeologists have to deal with serious difficulties to differentiate between processes that ultimately are responsible for the formation of stratigraphic units. Sometimes we face problems related with depositional units in multilayered deposits and other times, we ask for the character of some dark surface soils, very similar to natural paleosols and usually associated with archaeological findings. In both cases, the problems we must address concern the relative impact of human activities. The imbalance between anthropic and natural processes in the formation of archaeological deposits is crucial for a correct interpretation of the processes involved in the formatio…

Growth pattern of underlithified strata during thrust-related folding

2004

Abstract Asymmetric anticlines with overturned or steeply dipping forelimbs and gently dipping backlimbs are generally interpreted as thrust-related folds. Fold asymmetry occurs as a consequence of forelimb rotation. If deformation takes place in environments dominated by submarine sedimentation, the limbs coincide with the slope (depositional surface) and rotation reflects slope steepening. If folds are nucleated in poorly or unlithified deposits, growth geometry also depends on the properties of the media, such as cohesion and the angle of internal friction. For cohesionless deposits, the tilting of the slope influences the equilibrium of the soft sediments, resulting in gravity-driven fl…

Facies and facies association of the siliciclastic Brak River and carbonate Gemsbok formations in the Lower Ugab River valley, Namibia, W. Africa

2007

Abstract The Neoproterozoic Zerrissene Turbidite Complex of central-western Namibia comprises five turbiditic units. From the base to the top they are the Zebraputs Formation (greywacke and pelite), Brandberg West Formation (marble and pelite), Brak River Formation (greywacke and pelite with dropstones), Gemsbok River Formation (marble and pelite) and Amis River Formation (greywacke and pelites with rare carbonates and quartz-wacke). In the Lower Ugab River valley, five siliciclastic facies were recognised in the Brak River Formation. These are massive and laminated sandstones, classical turbidites (thick- and thin-bedded), mudrock, rare conglomerate and breccia. For the carbonate Gemsbok R…

Depositional Environment of the Devonian Quartz Sandstones in the Bāle Sand Pits

2014

This paper summarises data about the depositional environment of Devonian quartz sandstones in Latvia and discusses new fieldwork data from Bāle 1 and Bāle 2 sand pits. The commercial bed in these sand pits is composed of fine to gravel size grained white and pale gray sandstones with mud clasts and quartz pebbles in places. Studies in Bāle sand pit sectors 1 and 2 suggest the deposition of sediments in details channel and sand bars, with the scarce influence of tidal processes on sedimentation.