NEW CONSTRAINTS ON THE LATE PLEISTOCENE INCISION HISTORY OF THE ANIMAS RIVER, SOUTHWEST COLORADO

2020 ◽  
Author(s):  
Alexander Thomson ◽  
◽  
Jonathan E. Harvey ◽  
Mary L. Gillam
2020 ◽  
Vol 35 (8) ◽  
pp. 1046-1056
Author(s):  
Luisa Patiño ◽  
Maria Isabel Velez ◽  
Marion Weber ◽  
César A. Velásquez‐r ◽  
Santiago David ◽  
...  

1987 ◽  
Vol 36 ◽  
pp. 275-287
Author(s):  
Margit Jensen ◽  
Elsebeth Thomsen

The diagenetic history of the skeletal elements of Late Pleistocene-Holocene Ophiura sarsi from the shelf off northern Norway (Andfjorden, Malangsdjupet) is elucidated by comparison with natural and induced degradation of the skeletal elements of Recent ophiuroids (brittle stars) and asteroids (sea stars) from Danish waters. Dissolution features ("core-and-rind") in the trabeculae of fossil and Recent echinoderm stereom are initiated during death and early decay of organic tissue in the animals. The trabeculae have a polycrystal­line lamellar ultrastructure and lose their older central part during later stages of dissolution, which are dependant on undersaturation of the sea-water with regard to CaC03• The presence of undersaturated sea-water is supported by palaeoecological studies (Thomsen & Vorren 1984, 1986) implying oxygen deficient periods in the Late Pleistocene and an increased biogenic production in the Holocene. Pyrite framboids are situated in the secondary voids within the trabeculae and in the pore space of the stereom of the Late Pleistocene elements. No pyrite is observed within the polycrystalline lamellar ultrastructure of the trabeculae. The Late Pleistocene "pyritization" took place during oxygen deficient periods at the sediment-water interface or within the reduced zone of the topmost sediment.


2020 ◽  
Vol 19 (4) ◽  
pp. 463-478
Author(s):  
Mai Duc Dong ◽  
Phung Van Phach ◽  
Nguyen Trung Thanh ◽  
Duong Quoc Hung ◽  
Pham Quoc Hiep ◽  
...  

The Simclast model has been verified and applied effectively in simulating the delta development for some major deltas in the world. In this study, we applied the model Simclast for simulating the history of the Red river delta development in late Pleistocene-Holocene. Results of the model reveal that the mainland of study area had reduced rapidly during transgression period (10,000-8,000 BP). The morphology changed significantly in the paleo-Red and Day river systems, but slightly in the paleo Thai Binh river system. The paleo-river network had been active in upper part before 11,000 BP and then shifted seaward until 2,000 BP. The river-sea interaction causes erosion and accumulation; as a result the morphology changed remarkably. The paleo-Thai Binh river had been inactive until 5,500 BP and then it was active but the morphology had not varied remarkably. The recent coastline generated from Simclast is relatively in accordance with the present coastline.


2001 ◽  
Vol 2 (2) ◽  
pp. 95 ◽  
Author(s):  
B. ALPAR

The Enez-Evros Delta, NE Aegean Sea, is located in one the most important wetlands in the world with its sandy offshore islands, abandoned channel mouths, sand-dunes, shoals, marshlands, saline lagoons and saltpans. It comprises very well developed sedimentary units and a prodelta lying on an older submarine delta. The present day elevations of the middle-late Pleistocene marine terraces indicate a regional tectonic uplift in the area. Due to lack of geophysical and bore hole data and partly due to its strategic position, the structural and stratigraphic features of the submarine extension of the delta are not known in detail. In this paper, Plio-Quaternary history of this delta and its submarine part on the Turkish shelf was explored by using high-resolution shallow reflection seismic profiles. The delta is formed by the alluvial deposits of the Enez-Evros River and shaped by their interaction with the sea. It takes place in front of a large and protected ancient bay which was filled rapidly over millennia. The sediments in the plateau off the river are principally pro-deltaic with muddy areas near the river mouths changing to muddy sand further out. The sea-level changes in Plio-Quaternary were characterised by three different seismic stratigraphic units on the folded Miocene limestone basement. In the late Pleistocene, the shelf area over an Upper Miocene basement was flooded during the Riss-Würm interglacial period, exposed in the Würm glacial stage, and flooded once again during the Holocene transgression.


Author(s):  
Tom D. Dillehay

Chapter 4 summarizes the construction, subsistence, and social correlates of Huaca Prieta, a mound site in the lower Chicama Valley on the north coast of Peru, from the earliest evidence of human presence in the Late Pleistocene (ca. 12,500 14C BP) through abandonment at 3,800 14C BP. Marine resources were important throughout the sequence, which saw an early advent of agriculture and increasing population, complexity, and monumentality.


Ibis ◽  
2020 ◽  
Vol 162 (4) ◽  
pp. 1198-1210
Author(s):  
Carina Carneiro de Melo Moura ◽  
Alexandre M. Fernandes ◽  
Alexandre Aleixo ◽  
Helder Farias Pereira de Araújo ◽  
Erich de Freitas Mariano ◽  
...  

1976 ◽  
Vol 13 (8) ◽  
pp. 1082-1092 ◽  
Author(s):  
Lewis H. King

A side-scan sonar survey along the western bank of the Laurentian Channel and on the western Grand Banks revealed the occurrence of iceberg furrows that are probably of Late Pleistocene age. The occurrence of furrows in the Gulf of St. Lawrence is significant in that it helps to date iceberg furrows along the northeast Newfoundland–Labrador margin of the northwest Atlantic, provides data on the history of deglaciation of the offshore area of the Atlantic Provinces, provides a means of evaluating sea level curves, and provides additional evidence for the broad regional extent of the Late Pleistocene shoreline at 115 to 120 m.


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