The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger Randall; Pigati, Jeffery S. Randall; Agenbroad, Larry D. Coastal California, on the eastern margin of the Pacific Rm, is very active tectonically and geomorphic expressions of this include uplifted marine terraces. There have been, however, conflicting estimates of the rate of late Quaternary Randall; Groves, Lindsey T.
Luminescence Ages of Feldspar Contaminated Quartz from Fluvial Terrace Sediments
The present work reports the first numerical ages obtained for the two highest fluvial terraces Qt1 and Qt2 of the Alcanadre River system Northeastern Spain representing the earliest remnants of Quaternary morphosedimentary fluvial activity in the Ebro basin. ESR dating method was applied to optically bleached quartz grains and both the Al and Ti centers were measured, in accordance with the Multiple Center approach.
These data provide some chronological insights on the beginning of the fluvial sedimentary processes in a scenario of incision maintained over Quaternary in the Ebro Basin. These are among the first numerical ages obtained for such high terraces in the Iberian Peninsula. Our results demonstrate the interest of using the Multiple Center approach in ESR dating of quartz, since the two centers provide complementary information, i.
The overall apparent consistency between the ESR age estimates and the existing preliminary chronostratigraphic framework may be considered as an empirical evidence that the Ti—Li center may actually work for Early Pleistocene deposits, whereas the Ti—H center shows some clear limitations instead.
In a staircase of six fluvial terraces, the Palaeolithic sites were found on the T4 terrace (+24 m, above river bed) which is made of a basal Lower Gravels unit (LG) and an overlying Upper Sands unit (US).
Terrace deposit ages were provided by 14C dating of charcoal fragments and optically stimulated luminescence OSL dating of sandy sediments. Along with pairing of many terrace tread heights, these data indicate episodic downcutting during the Holocene, with a mean incision rate of 0. Prior to 7 ka, the river incised to within3 m of current bankfull, but then aggraded by 5 m over at least a 10 km-long reach in an episode centered 7—6 ka.
Aggradation may relate to 1 increased hillslope sediment input from landslides and debris flows in steep tributary basins with abundant grussified granitic bedrock, 2 possible local landslide-damming of the channel, 3 decreased peak discharge, or 4 a combination of these factors. Middle Holocene channel aggradation ca.
Between 5 and 1. Modest aggradation to vertical stability of the South Fork Payette River at the 1. Three intervals of incision 5. Other possible drivers of channel incision include an increase in stochastic or climate-modulated large storms and floods and a reduction in delivery of hillslope sediment to the channel. Aggradation is more confidently tied to climate through increases in hillslope sediment delivery and or decreased stream power, both likely related to warmer, drier conditions including high-severity fires that reduce snowmelt and decrease vegetation cover on steep slopes.
Thus, the Holocene terraces of the South Fork Payette River do not reflect simple stepwise incision with periods of vertical stability and lateral migration, but record substantial episodes of aggradation as well. We infer that increases in hillslope erosion and mass movements combined with reduced discharges during prolonged droughts episodically reverse the post-glacial trend of downcutting, in particular during the middle Holocene.
Institute of geology – Remote sensing group
This sample makes it possible to thoroughly characterize a Middle Pleistocene hominin paleodeme and to address hypotheses about the origin and evolution of the Neandertals. Using a variety of techniques, the hominin-bearing layer could be reassigned to a period around , years ago. The sample shows a consistent morphological pattern with derived Neandertal features present in the face and anterior vault, many of which are related to the masticatory apparatus.
This suggests that facial modification was the first step in the evolution of the Neandertal lineage, pointing to a mosaic pattern of evolution, with different anatomical and functional modules evolving at different rates.
Dating fluvial terraces is often difficult, however. If suitable organic remains can be located, 14 C may be employed to date material deposited in the most recent of the late Pleistocene climatic cycles.
We applied a technique based on conventional single-aliquot regenerative-dose SAR protocol, modified with an IR pre-treatment to reduce the OSL contribution from feldspar for accurately measuring the dose in quartz. All investigated samples showed an ability to measure a beta dose given in the laboratory, a so called dose recovery test.
The dependence of the equivalent dose on thermal treatment was also examined. Dose rate calculations were based on spectral analysis of gamma measurements by a field spectrometer on site. The efforts to establish a chronology using the IR modified SAR technique produced reliable dose results in stratigraphic order. Results were reproducible and grouped broadly between ka for Bektemur, ka for Kizilca, ka for Aksalur and ka for Sahinkaya. Obtained results show that the studied area was controlled by tectonic activities within the last 50 ka and the sample Aksalur 2 was the loess deposit formed by aeolian activity.
Radiation Measurements 33 1: East European loesspalaeosol sequences: Palynology, stratigraphy and correlation.
Settlements on morphological units of the western Indo-Gangetic plain see Fig. A Early and Mature Harappan sites, with names of some major urban centers: The Harappans were agrarian but developed large, architecturally complex urban centers and a sophisticated material culture coupled with a robust trade system.
In contrast to the neighboring hydraulic civilization of Mesopotamia 14 and to Egypt 15 , Harappans did not attempt to control water resources by large-scale canal irrigation Socio-economic theories have been invoked to address the collapse of urban Harappan society, including foreign invasions, social instabilities, and decline in trade 4. Alternatively, environmental factors were suggested to play a decisive role in the decline 1 , 2 , 8 ; among these, regional aridification, hydrological changes such as the drying or capture of the Ghaggar-Hakra system 3 , 4 , 7 , 19 , 20 , as well as human-induced environmental degradation 21 have been advanced.
By radiocarbon dating these plant fossils, and mapping the stratigraphy of the fluvial terrace deposits, we can reconstruct the history of incision and aggradation of several stream systems in the Atacama over the last 10, years (Rech et al. ; ).
Chronology and driving forces Titelangaben Kolb, Thomas: Chronology and driving forces. Angaben zu Projekten Oberfrankenstiftung Abstract Generally controlled by the development of the Rhenish drainage system, the fluvial history of northern Bavaria is characterized by a high complexity, which is reflected in the irregular spatial alignment of river courses.
In particular, this applies to the headwaters of the Main River, which is, with a total length of about km, the longest right-bank tributary of the Rhine River system. This dissertation deals with the mid- and late-Pleistocene development of the drainage network in the vicinity of the city of Bayreuth. Dominated by the two headwater streams of the Main River, the Red Main River and the White Main River, and by the river Warme Steinach, the area has been the subject of scientific research for more than years.
So far, these investigations have focused mainly on the application of well-established methods from the field of sedimentology and lithology, which finally allowed deriving a complex landscape evolution model. Up to now, however, investigations have been lacking that could provide reliable information on the timing and dynamics of these complex river deflections. The overall objective of this PhD-thesis is therefore to establish a reliable chronological framework for the mid- and late-Pleistocene evolutionary stages of the local drainage system, which is based on modern numerical dating methods.
Our study is located in the unusually wide Trebgast Valley, which is situated in the north of the city of Bayreuth and has been identified as a former valley of the Red Main River. This valley and its well-preserved fluvial and slope deposits offered ideal conditions for palaeoenvironmental research. Besides additional lithological analyses of fluvial gravel and the evaluation of a high-resolution digital terrain model, the methodological focus was on the application of innovative methods of luminescence dating.
The results of this PhD-thesis partially contradict the age estimates of earlier studies and indicate a much more complex landscape evolution than previously assumed. For the older fluvial terraces identified within the research area, new techniques of luminescence dating had to be applied, which allow a significant extension of the dating range.
River terraces (tectonic–climatic interaction)
Introduction An ever-expanding inventory of fault slip-rates spanning various time intervals reveals contrasting spatial and temporal patterns of strain for active faults within the eastern California shear zone ECSZ. Comparison of these data, derived from geologic, geomorphic, and paleoseismic records, with geodetic estimates of fault loading affords unparalleled opportunity to investigate the dynamics of earthquake processes and the evolution of an intracontinental plate boundary fault system.
To address this inconsistency, we targeted a series of previously unrecognized fluvial terraces related to overtopping and outflow from pluvial Owens Lake that cross the fault and record dextral offset since Late-Pleistocene time. Methods Geologic constraints on displaced Quaternary geomorphic features along the Little Lake fault zone come from geologic and geomorphic mapping and high-resolution digital topography collected using a Riegl LMS-Z i terrestrial laser scanner TLS.
Fluvial strath terraces provide a record of river incision and the timing of climatic perturbations to the fluvial system. Dating depositional surfaces like terraces that .
The study area is located between the easternmost part of the southern Apennine chain and the Gargano promontory and it is characterized by several orders of terraced fluvial deposits, disconformably overlying lower Pleistocene marine clay and organized in a staircase geometry, which recorded the emersion and the long-term incision history of this sector since mid-Pleistocene times. We used the spatial and altimetric distribution of several orders of middle to late Pleistocene fluvial terraces in order to perform paleotopographic reconstruction and GIS-aided eroded volumes estimates.
Then, we estimated denudation rates on the basis of the terraces chronostratigraphy, supported by published OSL and AAR dating. Middle to upper Pleistocene denudation rates estimated by means of such an approach are slightly lower than 0. The analysis of longitudinal river profiles using the stream power erosion model provided additional information on the incision rates of the studied area.
Middle to late Quaternary uplift rates about 0. The approach adopted in this work has demonstrated that erosion rates traditionally obtained by quantitative geomorphic analysis and k sn estimations can be successfully integrated to quantify rates of tectonic or geomorphological processes of a landscape approaching steady-state equilibrium.
Luminescence Dating of Fluvial Deposits from the Weser Valley, Germany
Hide Figure 5 Comparison between changes in paleo-precipitation and stream channel morphology figure adapted from Rech et al. Precipitation is reconstructed from rodent middens Latorre et al. Periods of stream aggradation and incision are derived from radiocarbon dating of fluvial terraces and mapping of fluvial stratigraphy. Details Description Climate on earth is constantly changing.
Optically stimulated luminescence (OSL) dating shows that fine-grained and homogeneous sediment in the studied fluvial terrace was deposited at ± ka and ± ka. These dating results are consistent with the age of ± ka cal B.P. from the radiocarbon dating of a charcoal fragment.
By studying both relative soil ages and absolute soil ages we believe that a robust interpretation of the glacial history in Taylor Valley is possible. There are about fluvial terraces in Taylor Valley, ranging in elevation from sea level to m. These terraces have been dated by 14 C dating of buried algal layers, yielding ages ranging from 8, — 23, 14 C years BP Stuiver et al. What’s wrong with the 14 C dates? Cold-dry environments tend to act like freezers, preserving organic carbon and recycling old material.
It is well documented that algae in the Dry Valleys is readily transported by streams and wind, making issues of carbon recycling a major problem. Potential recycling sources are described below: RadioCarbon Reservoir Effect – Old carbon from glacial meltwater can be incorporated into growing algal mats. Wind-Blow Algae – Algal mats desicate during the wintermonths and are blown away by strong katabatic winds from the Antarctic Plateau.
Water-Transported Algae – Upstream errosion can recycle old burried algae that is then incorporated into fluvial deposits. Figure 2 14 C ages of fluvial terraces in Taylor Valley organized by the drainage or stream in which they were found compiled from Hall et al. Terraces at similar elevations, but different drainages, do not have similar ages, as would be expected from a valley-wide paleolake.
Fluvial Terraces Figure 3 A large fluvial terrace located at 80 m on Crescent Stream a , a soil profile with foreset beds evident and no aeolian horizon b , cross-bedded topsets c , and gravelly sand with an aeolian horizon evident d.
Fluvial landscapes of the Harappan civilization
Article Recommendations Abstract Luminescence dating was applied on coarse-grained monomineralic potassium-rich feld-spar and polymineralic fine-grained minerals of five samples derived from fluvial deposits of the Riv-er Weser in northwestern Germany. In order to obtain a stable luminescence signal, only off-time IRSL signal was rec-orded.
Performance tests gave solid results. The Somme valley terrace system northern France ; a model of river response to Quaternary climatic variations since , BP.
The debris flow fan is much larger than fluvial terraces on the other tributary, 25 but mean transit times (± σ) in both reservoirs are similar: ± a and ± .
Quaternary Sediments in Sichuan Basin. Sichuan Scientific and Technical Publishers, Study on the Three Gorges terraces I: Geomorphic evolution of the Yangtze Gorges and the time of their formation. Distribution of late Quaternary active faults and its tectonic significance in the Beishan region, Gansu Province, China. Geological Review, , 51 3: Luminescence dating applications in geomorphological research.
Geomorphology, , 29, Luminescence dating of fluvial sediments and overbank deposits from Gossau, Switzerland: Quaternary Geochronology, , Radiation Measurements, , 27 Bleaching of ESR signal by the sunlight: Applied Radiation and Isotopes, , Artificial optical bleaching of the Aluminium center in quartz implications to ESR dating of sediments.