Late Pleistocene Terrace Deposits Research Articles

Palynological analysis of the Late Pleistocene terrace deposits of Lake Van, eastern Turkey: Reconstruction of paleovegetation and paleoclimate

Paleovegetation and paleoclimate reconstruction of a Late Pleistocene terrace of Lake Van (northern part of lake; Erciş Çelebibağı region) was based on pollen analysis from continuous laminated sediments. According to the pollen analysis, NAP pollen values are predominantly abundant. Chenopodiaceae, Artemisia and Poaceae were the prevailing plants, and Chenopodiaceae was the dominant paleoflora element during Late Pleistocene. Pollen data indicate halophyte vegetation. Climate was colder and drier.

Dating of Late Pleistocene terrace deposits of the River Rhine using Uranium series and luminescence methods: Potential and limitations

Uranium-series dating of pedogenic carbonate crusts from fluvial gravels is tested using Optically Stimulated Luminescence (OSL) ages as references. OSL dating yielded ages of 30–15 ka and 13–11 ka, which correlate with the cold periods of the Last Glacial Maximum and the Younger Dryas. These ages are internally coherent and consistent with the geological background and are thus regarded as reliable. Most of the U/Th results scatter widely in the 230Th/ 232Th vs. 234U/ 232Th isochron diagram, making regression unrealistic. Semiquantitative age estimates from the data were found to be mostly older than the OSL ages and the geological context. It is suggested that a heterogeneous initial 230Th input, not relatable to a detrital component, is responsible for the observed discrepancies. This input may be due to bacterial activities and Th transport on organic colloids. It appears necessary to avoid samples where bacteria could have contributed to carbonate precipitation. Further, the relative importance of this problem decreases with sample age, so that U/Th dating of sinters is expected to be more reliable in the >100 ka age range.

Late Quaternary activity of the Feldbiss Fault Zone, Roer Valley Rift System, the Netherlands, based on displaced fluvial terrace fragments

The Meuse River crosses the Feldbiss Fault Zone, one of the main border fault zones of the Roer Valley Graben in the southern part of the Netherlands. Uplift of the area south of the Feldbiss Fault Zone forced the Meuse River to incise and, as a result, a flight of terraces was formed. Faults of the Feldbiss Fault Zone have displaced the Middle and Late Pleistocene terrace deposits. In this study, an extensive geomorphological survey was carried out to locate the faults of the Feldbiss Fault Zone and to determine the displacement history of terrace deposits. The Feldbiss Fault Zone is characterized by an average displacement rate of 0.041–0.047 mm a −1 during the Late Pleistocene. Individual faults show an average displacement rate ranging between 0.010 and 0.034 mm a −1. The spatial variation in displacement rates along the individual faults reveals a system of overstepping faults. These normal faults developed by reactivation of Paleozoic strike-slip faults. As fault displacements at the bases of the younger terrace deposits are apparently similar to the tops of the adjacent older terrace, the age of these horizons is the same within thousands of years. This implies that the model of terrace development by rapid fluvial incision followed by slow aggradation does apply for this area.

Sedimentology of Terrace Deposits at Bend Area of Wabash River: ABSTRACT

Late Pleistocene terrace deposits lining the valley walls of the Wabash River record the change in fluvial regime imposed on the river by the advance and disintegration of the Trafalgar (East White Sublobe) ice sheet. In the lower part of the terraces, sediments accumulated in a shallow braided stream environment where fluctuating flow was controlled by storms and by diurnal and seasonal melt cycles. The sediments consists of: (1) horizontally bedded cobble gravels deposited as longitudinal bars and channel lags; (2) planar cross-bedded pebble gravels that accumulated as transverse bars and lateral accretionary wedges on bar margins; (3) trough cross-bedded pebbly sands deposited in channels during low flow stages; and (4) thin ripple-bedded sands and silts, and laminated muds deposited by spillover into abandoned channels and irregularities on bar surfaces. Short-term flow variations are recorded by thin alternating bar and channel sediments, which were deposited during waning flow, when channels were cut and filled on surfaces of bars formed during flood stage. Longer term variations are recorded by thicker sequences consisting of thin bar and channel deposits formed during high but fluctuating flow, alternating with thick channel deposits that accumulated during prolonged periods of low flow. These braided stream sediments were deposited during ice advance and intitial stages of ice disintegration. The other type of deposit occurs in the upper part of the terrances and consists of large-scale trough cross-bedded cobble gravels. These sediments accumulated after the drainage network from the disintegrating ice field was fully developed and uniform rapid flow was established. End_of_Article - Last_Page 927------------

Late Pleistocene terrace deposits at Beckford, Worcestershire, England

AbstractThe Pleistocene deposits in the area of the village of Beckford, in the Carrant Valley, Worcestershire are described. A radio‐carbon date of 27,650±250 years B.P. has been obtained from plant material in the terrace deposits in the valley. Detailed studies have been made of the terrace sediments and of the remains of Mollusca and Coleoptera in fossiliferous layers. Frost structures are described and their stratigraphy considered. The nature of the local environment and regional climate in the final stages of the Upton Warren Interstadial period is reconstructed in detail. The terrace appears to have aggraded in a periglacial environment, dominated initially by solifluction processes. Extensive solifluction may have led to local diversions of drainage. In time, the climate deteriorated, becoming cooler and somewhat less continental with the onset of the main Devensian glaciation. This latter stage was characterised by extensive ice‐wedge growth, aeolian activity and, subsequently, by river incision.

Palynological Study of the late Pleistocene Terrace Deposits of Hokuriku Region, Central Japan, with Reference to the Climatic Condition during Shimosueyoshi age(Riss Wurm Interglacial ?) in Japan : The Palynological Studies of Cenozoic Strata in Hokuriku Region, Central Japan. Part III(<SYMPOSIUM>QUATERNARY OF JAPAN)

Palynological Study of the late Pleistocene Terrace Deposits of Hokuriku Region, Central Japan, with Reference to the Climatic Condition during Shimosueyoshi age(Riss Wurm Interglacial ?) in Japan : The Palynological Studies of Cenozoic Strata in Hokuriku Region, Central Japan. Part III(<SYMPOSIUM>QUATERNARY OF JAPAN)