Pliocene–Pleistocene fluvial/wave-dominated deltaic sedimentation: the Pamisos delta, southwest Peloponnesus, Greece

1994 ◽  
Vol 131 (5) ◽  
pp. 653-668 ◽  
Author(s):  
Abraham Zelilidis ◽  
Nikolaos Kontopoulos

AbstractA fluvial /wave-dominated delta was formed during late Pliocene times in southwestPeloponnesus, influenced by NNW—SSE and ENE—WSW trending faults. The depositional patternremained unchanged through early Pleistocene times, when the pre-existing active faults with WNW—ESE extension were combined with an eastward asymmetrical subsidence of the graben. Inthe deltaic environment, marshes, lakes and lagoons were created in the western parts, whereas largequantities of sediments were deposited in the central and eastern parts adjacent to basin marginsof steeper relief.This study combines grain size parameters, total organic matter, carbonate and clay mineralogyand structural analysis to: (a) determine the pattern of sedimentation in sub-environments and (b)create a fluvial/wave-type deltaic depositional model, and distinguish between delta-plain, delta-front and pro-delta environments. The Pliocene-Pleistocene, fluvial/wave-dominated delta model inthis study can be used to predict deltaic sedimentation in analogous basins.

1988 ◽  
Vol 125 (3) ◽  
pp. 241-255 ◽  
Author(s):  
C. R. Fielding ◽  
M. Al-Rubaii ◽  
E. K. Walton

AbstractThe Lower Limestone Group, which outcrops extensively on the east coast of Fife, southeast Scotland, consists of interbedded sandstones, siltstones and claystones with occasional coal seams, and limestone beds. Several of the coals have been mined economically in the past.The sequence was deposited in a shallow-water, deltaic setting. Three facies associations have been distinguished; (1) laminated claystones, and marine bioclastic limestones, which were deposited in prodelta and marine shelf environments, (2) crudely coarsening-upward sandstone units, interpreted as delta front deposits of fluvially-dominated though wave-influenced, shallow-water deltas, and (3) interbedded clastic sedimentary rocks and coals, deposited in delta plain environments. The sequence as a whole accumulated by repeated progradation and abandonment of deltaic complexes.Palaeosol profiles of four types are superbly preserved within the delta plain facies association. These are (1) organic soils (peats), now coal seams, (2) gley palaeosols, which formed in persistently waterlogged conditions, (3) freely drained soils which formed on a quartz sand-rich substrate, and (4) similar profiles formed by free drainage through variable substrates and involving B horizon accumulation of concretionary iron oxides. Compound palaeosols are common.Deposition of the Lower Limestone Group was influenced by the tectonic and volcanic instability of the Fife area during Visean times. Frequent seismic events centred on active fault lines caused local uplift of parts of the normally waterlogged delta plain environment, allowing the formation of well-drained soils. Peats (coals) were best developed and least affected by oxidation in an elongate, fault bounded zone of enhanced subsidence.


2021 ◽  
Author(s):  
Daan Beelen ◽  
Lesli Wood ◽  
Mohamed Zaghloul ◽  
Michiel Arts ◽  
Sebastian Cardona

Sea strait geographies amplify tidal currents, which can result in the formation of tidal strait deposits with a symmetrical facies arrangement. It can be problematic to distinguish such confined tidal strait deposits from strait systems that developed in less constricted settings. To push a more robust differentiation between the confined tidal strait model and a model for less constricted tidal deposits, this study presents an example of a strait-adjacent delta and compares it to the existing model of confined tidal straits. The strait-adjacent delta interpretations are based on an exposed succession in Northern Morocco, that formed in the Miocene Rifian Corridor. The multi-km, seismic-scale exposures at the Ben Allou locality, formed in a region with a largely unconstrained coastline. Clayey and silty portions dominate the distal offshore and prodelta facies, while the proximal delta front and delta plain are comprised of carbonate-rich sandstones. These sandstones exhibit complex architectures of stacked channels and dunes in the delta front, and mud drape-bearing sand sheets on the delta plain. It is shown that the strait-adjacent delta model that is presented herein, is different from a confined tidal strait deposit as it has an asymmetric facies arrangement, and a basinward reduction in depositional energy.


2001 ◽  
Vol 16 (5) ◽  
pp. 535-543 ◽  
Author(s):  
Katherine Mc Intyre ◽  
Margaret L. Delaney ◽  
A. Christina Ravelo

Antiquity ◽  
2017 ◽  
Vol 91 (358) ◽  
Author(s):  
Sirvan Mohammadi Ghasrian

Despite the potential importance of southern Iran, and the Persian Gulf area in particular, for discussions on the dispersal of early hominins from Africa into Eurasia during the late Pliocene and early Pleistocene (Bar-Yosef & Belfer-Cohen 2001; Rose 2010), this area has remained almost unexplored until recently. Historically, Palaeolithic survey and excavations in Iran have mainly concentrated in western regions, especially the Zagros Mountains. As a result of recent studies, however, evidence for Palaeolithic sites in the southern regions of Iran, from Fars province to Qeshm Island, has greatly increased (Dashtizade 2009, 2010). Even with this improvement, no sites of Lower Palaeolithic date have yet been reported from the southern coastal areas on one of the proposed early hominin routes into Eurasia. As a result, it has been suggested that the few Lower Palaeolithic sites reported from other parts of Iran, especially in the west (e.g. Biglari & Shidrang 2006), were not populated from the south.


2012 ◽  
Vol 8 (5) ◽  
pp. 1435-1445 ◽  
Author(s):  
J. Etourneau ◽  
C. Ehlert ◽  
M. Frank ◽  
P. Martinez ◽  
R. Schneider

Abstract. The global Late Pliocene/Early Pleistocene cooling (~3.0–2.0 million years ago – Ma) concurred with extremely high diatom and biogenic opal production in most of the major coastal upwelling regions. This phenomenon was particularly pronounced in the Benguela upwelling system (BUS), off Namibia, where it is known as the Matuyama Diatom Maximum (MDM). Our study focuses on a new diatom silicon isotope (δ30Si) record covering the MDM in the BUS. Unexpectedly, the variations in δ30Si signal follow biogenic opal content, whereby the highest δ30Si values correspond to the highest biogenic opal content. We interpret the higher δ30Si values during the MDM as a result of a stronger degree of silicate utilisation in the surface waters caused by high productivity of mat-forming diatom species. This was most likely promoted by weak upwelling intensity dominating the BUS during the Late Pliocene/Early Pleistocene cooling combined with a large silicate supply derived from a strong Southern Ocean nutrient leakage responding to the expansion of Antarctic ice cover and the resulting stratification of the polar ocean 3.0–2.7 Ma ago. A similar scenario is hypothesized for other major coastal upwelling systems (e.g. off California) during this time interval, suggesting that the efficiency of the biological carbon pump was probably sufficiently enhanced in these regions during the MDM to have significantly increased the transport of atmospheric CO2 to the deep ocean. In addition, the coeval extension of the area of surface water stratification in both the Southern Ocean and the North Pacific, which decreased CO2 release to the atmosphere, led to further enhanced atmospheric CO2 drawn-down and thus contributed significantly to Late Pliocene/Early Pleistocene cooling.


2018 ◽  
Vol 89 (2) ◽  
pp. 533-562 ◽  
Author(s):  
Gaia Crippa ◽  
Andrea Baucon ◽  
Fabrizio Felletti ◽  
Gianluca Raineri ◽  
Daniele Scarponi

AbstractThe Arda River marine succession (Italy) is an excellent site to apply an integrated approach to paleoenvironmental reconstructions, combining the results of sedimentology, body fossil paleontology, and ichnology to unravel the sedimentary evolution of a complex marine setting in the frame of early Pleistocene climate change and tectonic activity. The succession represents a subaqueous extension of a fluvial system, originated during phases of advance of fan deltas affected by high-density flows triggered by river floods, and overlain by continental conglomerates, indicating a relative sea level fall and the establishment of a continental environment. An overall regressive trend is observed through the section, from prodelta to delta front and intertidal settings. The hydrodynamic energy and the sedimentation rate are not constant through the section, but they are influenced by hyperpycnal flows, whose sediments were mainly supplied by an increase in Apennine uplift and erosion, especially after 1.80 Ma. The Arda section documents the same evolutionary history of coeval successions in the Paleo-Adriatic region, as well as the climatic changes of the early Pleistocene. The different approaches used complement quite well one another, giving strength and robustness to the obtained results.


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