Home  About us  Contact
 

Sedimentary Evolution (sedimentary + evolution)

Distribution by Scientific Domains
Earth and Environmental Science100%

Selected Abstracts

Pomeranian basin (NW Poland) and its sedimentary evolution during Mississippian times

GEOLOGICAL JOURNAL, Issue 2-3 2008
Hanna Matyja
Abstract The Carboniferous sedimentary history of the Pomeranian Basin (NW Poland) begins with Hastarian open-marine carbonates and is terminated with ?lower Asbian terrestrial deposits in the north-eastern part and, ?upper Asbian or Brigantian, open-marine shales in the south-western part of the basin. The ?latest Viséan, Serpukhovian and early Bashkirian was a period of regional non-deposition and erosion. In the Upper Bashkirian,Gzhelian strata, an alluvial depositional environment was recognized. The Mississippian depositional history of the area has been punctuated by several, regional-scale events: (1) during the late Famennian,early Tournaisian times anoxic conditions developed over the entire basin. The results of both conodont and miospore studies show the presence of a stratigraphic gap within this sequence (which also show extremely reduced thicknesses), that comprises the uppermost Famennian (Middle and Upper praesulcata conodont zones) and the lowermost Hastarian (sulcata,sandbergi conodont zones). This stratigraphic gap probably resulted from some chemical and/or hydrodynamical factors rather than from any tectonic uplift; (2) volcanic activity on the nearby East European Craton (EEC), which was the source of large amounts of detrital (volcaniclastic) material supplied to the Pomeranian Basin during the Early crenulata,?early anchoralis-latus chrons (late Hastarian,early Ivorian), caused with time the gradual shallowing of the sedimentary environment. This shallowing trend began in the Early typicus Chron (early Ivorian) and terminated with terrestrial deposits in the early Asbian. The sedimentary succession and specific phenomena recognized in this structurally unstable basin, displays a pattern partly different from that observed in some areas in Europe. It would appear that other local factors, such as tectonic mobility of the hinterland area (EEC) and the Pomeranian Basin floor, were the possible causes of observed variations and relative sea-level changes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Pendleian (early Serpukhovian) marine carbonates from SW Spain: sedimentology, biostratigraphy and depositional model

GEOLOGICAL JOURNAL, Issue 1 2004
P. Cózar
Abstract The San Antonio,La Juliana tectono-sedimentary unit contains the only Namurian marine carbonates in the southwestern part of the Iberian Peninsula. The analysis of this unit is fundamental in understanding the sedimentary evolution and tectonic movements which operated during the Namurian in this area. Using foraminifera the succession has been assigned to two biozones (Zones 17 and 18), both occurring in the Pendleian (early Namurian). Seven stratigraphic sections have been analysed: San Antonio, Burjadillo, Lavadero de la Mina, Cornuda, Lozana, Caridad and Via Crucis. The stratigraphic succession of the San Antonio,La Juliana Unit consists of olistolites in the basal part, with common debris-flow deposits (mainly of carbonates, with minor siliciclastic rocks), and turbidites, all of them embedded in shales. These rocks, interpeted as slope deposits, pass up into shallow-water platform facies, with sediments characteristic of the inner platform and tidal flats. Above these rocks, terrigenous deltaic deposits occur. Thus, the stratigraphic sections show an overall shallowing-upward trend. The isolation of some outcrops, and the duplication and absence of some parts of the stratigraphic succession are explained by tectonic movements. Overall, tectonic factors seem to be the main control rather than glacio-eustatic or autocyclic processes, and sedimentation took place in a strike-slip regime. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Tectonic vs. climate forcing in the Cenozoic sedimentary evolution of a foreland basin (Eastern Southalpine system, Italy)

BASIN RESEARCH, Issue 6 2009
N. Mancin
ABSTRACT This paper discusses the Cenozoic interaction of regional tectonics and climate changes. These processes were responsible for mass flux from mountain belts to depositional basins in the eastern Alpine retro-foreland basin (Venetian,Friulian Basin). Our discussion is based on the depositional architecture and basin-scale depositional rate curves obtained from the decompacted thicknesses of stratigraphic units. We compare these data with the timing of tectonic deformation in the surrounding mountain ranges and the chronology of both long-term trends and short-term high-magnitude (,aberrant') episodes of climate change. Our results confirm that climate forcing (and especially aberrant episodes) impacted the depositional evolution of the basin, but that tectonics was the main factor driving sediment flux in the basin up to the Late Miocene. The depositional rate remained below 0.1 mm year,1 on average from the Eocene to the Miocene, peaking at around 0.36 mm year,1, during periods of maximum tectonic activity in the eastern Southern Alps. This dynamic strongly changed during the Pliocene,Pleistocene, when the basin-scale depositional rate increased to an average of 0.26 mm year,1 (Pliocene) and 0.73 mm year,1 (Pleistocene). This result fits nicely with the long-term global cooling trend recorded during this time interval. Nevertheless, we note that the timing of the observed increase may be connected with the presumed onset of major glaciations in the southern flank of the Alps (0.7,0.9 Ma), the acceleration of the global cooling trend (since 3,4 Ma) and climate variability (in terms of magnitude and frequency). All these factors suggest that combined high-frequency and high-magnitude cooling,warming cycles are particularly powerful in promoting erosion in mid-latitude mountain belts and therefore in increasing the sediment flux in foreland basins. [source]

Long-term Callovian,Oxfordian sea-level changes and sedimentation in the Iberian carbonate platform (Jurassic, Spain): possible eustatic implications

BASIN RESEARCH, Issue 2 2008
Javier Ramajo
ABSTRACT Facies analysis across the carbonate platform developed during the Callovian,Oxfordian in the northern Iberian basin (Jurassic, Northeast Spain) is used to characterize successive stages of sedimentary evolution, including palaeoenvironmental reconstructions showing the distribution of a wide spectrum of facies, from ferruginous oolitic, peloidal, spongiolithic to intraclastic. The studied successions consist of two long-term transgressive,regressive cycles bounded by a major unconformity with a major gap, comprising at least the upper Lamberti (Callovian) and Mariae (Oxfordian) Zones. Major transgressive peaks of these two cycles occurred at the end of the Early Callovian (late Gracilis Zone) and at the end of the Middle Oxfordian. The Callovian and Oxfordian successions were further divided into three and seven higher frequency cycles, respectively. The modelling of two sections (i.e. Ricla and Tosos) located 40 km apart in the more subsident open platform areas, allows the reconstruction of two curves showing a similar evolution of long-term sea-level changes that are in theory eustatic, though subject to uncertainties derived form the assumptions required for their construction. The changes affecting the northern Iberian basin seem to reflect nearly homogeneous subsidence (rates around 2 cm kyr,1) combined with possible eustatic changes including an Early Callovian rise, a fall at the middle Callovian,earliest Oxfordian (i.e. the Anceps,Mariae Zones), with average long-term rates around 2 cm kyr,1 (total fall of 40,60 m), a period of lowstand at the Early,Middle Oxfordian transition and a long-term rise at the Middle,Late Oxfordian transition (Transversarium and Bifurcatus Zones). Facies distribution across the Iberian platform indicates a progressive Middle,Late Callovian relative sea-level fall rather than a rapid relative sea-level fall at the end of the Callovian. After this falling episode, the progressive onlap over the swell areas during the Early Oxfordian and at the beginning of the Middle Oxfordian indicates a period of accommodation gain, which is explained by the combined effects of continuous subsidence across the platform and reduced sedimentation rates in spite of the possible eustatic lowstand. Eustatic lowstand, combined with other factors (ocean water circulation, volcanism) could help to explain the loss of carbonate production during the latest Callovian,Early Oxfordian, previous to the widespread eustatic rise and warning recorded at the onset of the Transversarium Zone (Middle Oxfordian). [source]