Characteristics of the fifth paleosol complex (S-5) in the southernmost part of the Chinese Loess Plateau and its paleo-environmental significance
Huang, C.Q. ; Tan, W.F. ; Wang, M.K. ; Koopal, L.K. - \ 2014
Catena 122 (2014). - ISSN 0341-8162 - p. 130 - 139.
asian monsoon evolution - late quaternary - deposits - soils - sea
The most prominent paleosol unit in the Chinese Loess Plateau (CLP) is the fifth paleosol complex (S-5) with its well-developed very thick and dark colored pedons. To provide more insight in the formation of S-5 and its environmental significance, the pedogenesis and clay mineral transformation in the S-5 of the Wugong section (Shaanxi Province) on the southernmost CLP are analyzed. S-5 at the Wugong section is essentially composed of three well-developed reddish pedons (i.e., S5-1, S5-2, S5-3) which signify three glacial-interglacial climatic fluctuations during its formation. Complete decalcification in each pedon and a calcic horizon of only 30-50 cm in thickness beneath each of the three pedons suggests that after deposition the pedons developed with a relatively stable surface in a sustained warm and humid climate. Clay formation in the S-5 includes neogenesis of clay materials by in situ post-depositional weathering and mechanical migration of the fine fraction after complete decalcification. Complete leaching of CaCO3, intensive clay formation (with 60-100% higher clay content than that in the overlying and underlying loess (L-5 and L-6)) and extremely high magnetic susceptibility in the S-5 pedons reflected a warmer, more humid climate and soil environment for pedogenesis than in the 'optimum' Holocene. However, the chemical alteration of the phyllosilicate minerals was weak and restrained by the hard calcic horizon, the compact argillic horizon and the flat terrain. The major clay mineral weathering processes during the formation of the S-5 pedons at the Wugong section were depotassication, hydrolysis of primary minerals and degradation of chlorite. The pedogenesis in a loess-paleosol sequence and its pedogenic environment can best be deduced from combined data on pedogenic properties, and geochemical and mineralogical characteristics. (c) 2014 Elsevier B.V. All rights reserved.
Edifice growth and collapse of the Pliocene Mt. Kenya: Evidence of large scale debris avalanches on a high altitude glaciated volcano
Schoorl, J.M. ; Veldkamp, A. ; Claessens, L.F.G. ; Gorp, W. van; Wijbrans, J.R. - \ 2014
Global and Planetary Change 123 (2014)Part A. - ISSN 0921-8181 - p. 44 - 54.
african climate-change - mount kenya - tectonic evolution - gregory rift - east-africa - deposits - geochronology - uplift - pleistocene - himalaya
The cyclic growth and destruction of the Late Cenozoic Stratovolcano Mt. Kenya have been reconstructed for its southeastern segment. At least three major debris avalanche deposits have been reconstructed and dated. The oldest deposits indicate an edifice collapse around 4.9 Ma (40Ar/39Ar), followed by a larger event around 4.1 Ma (40Ar/39Ar). The last and best preserved debris avalanche deposit, with still some morphological expression covering the whole 1214 km2 SE sector, occurred around 2.83 Ma (40Ar/39Ar). This very large debris avalanche event must have truncated the whole top of Mt. Kenya. Of the original typical hummocky relief, only local topographical depressions are still best visible and preserved. Using known geometric empirical parameters of the 3 preserved debris-avalanche deposits, the height of the sector collapse is estimated to be in the range of 5100–6500 m above the current height of 1000 m a.s.l. near the end lobe of the VDA deposits. This demonstrates that Mt. Kenya attained impressive altitudes during its main activity in the Pliocene, being one of the highest mountains in that time and was most probably covered by an ice cap. Correcting for the known net eastward tilting post eruptive uplift of approximately 500 m of the Mt. Kenya summit, our reconstruction indicates that an at least 5.6 to 7 km a.s.l. high active Mt. Kenya existed in the Pliocene landscape between 5.1 and 2.8 Ma. This volcano must have significantly contributed to regional environmental change, by catching rain on its eastern slopes and projecting a rain shadow towards the Kenya Rift valley in the west. The last major edifice collapse event around 2.8 Ma coincides with a major change in regional vegetation. This suggests that the truncating of Mt. Kenya may have caused significant changes in the local climate surrounding Mt. Kenya with possible implications for environmental change in the central Kenya Rift valley, the cradle of hominin evolution.
Are feldspar SAR protocols appropriate for post-IR IRSL dating?
Kars, R.H. ; Reimann, T. ; Wallinga, J. - \ 2014
Quaternary Geochronology 22 (2014). - ISSN 1871-1014 - p. 126 - 136.
anomalous fading correction - infrared stimulated luminescence - regenerative-dose protocol - k-feldspar - chinese loess - quartz - sediments - samples - deposits - signals
Recently proposed post-infrared infrared stimulated luminescence (post-IR IRSL or pIR) dating protocols have largely overcome problems associated with anomalous fading and have become increasingly important for age determination of Quaternary sediments. Here, we investigate the suitability of the proposed post-IR IRSL protocols for accurate equivalent-dose estimation on K-feldspar extracts. Our research focuses on potential sensitivity changes between the natural signal and the first test dose signal in single-aliquot regenerative dose (SAR) procedures that are not detected and thus not corrected using test-dose responses. For these investigations, we employed the Single Aliquot Regeneration and Added dose (SARA) procedure, which combines equivalent-dose estimation with a dose recovery test. Results indicated that high-temperature preheats (>260 °C for 60 s) may induce a trapping sensitivity change in IRSL signals measured at low temperature (100 °C) after a high temperature preheat. Our results indicate that the SAR protocol is appropriate for equivalent-dose determination using elevated-temperature pIR signals (e.g. pIR at 290 °C or multiple elevated temperature pIR at 250 °C). The SAR protocol may also be appropriate for equivalent-dose determination using low temperature pIR signals, provided that the combination of preheat and measurement temperature
Soil Food Web Changes during Spontaneous Succession at Post Mining Sites: A Possible Ecosystem Engineering Effect on Food Web Organization?
Frouz, J. ; Thébault, E. ; Pizl, V. ; Adl, S. ; Cajthaml, T. ; Baldrián, P. ; Hánel, L. ; Starý, J. ; Tajovský, K. ; Materna, J. ; Nováková, A. ; Ruiter, P.C. de - \ 2013
PLoS ONE 8 (2013)11. - ISSN 1932-6203 - 18 p.
northernmost record - middle eocene - miocene - oligocene - strenulagidae - ochotonidae - evolution - revision - deposits - poland
Lagomorphs (a group that consists of pikas, hares, rabbits and allies) are notable for their conservative morphology retained for most of their over 50 million years evolutionary history. On the other hand, their remarkable morphological uniformity partly stems from a considerable number of homoplasies in cranial and dental structures that hamper phylogenetic analyses. The premolar foramen, an opening in the palate of lagomorphs, has been characterized as an important synapomorphy of one clade, Ochotonidae (pikas). Within Lagomorpha, however, its phylogenetic distribution is much wider, the foramen being present not only in all ochotonids but also in leporids and stem taxa; its morphology and incidence also varies considerably across the order, even intraspecifically. In this study, we provide a broad survey of the taxonomic distribution of the premolar foramen in extant and fossil Lagomorpha and describe in detail the morphological variation of this character within the group. Micro-computed tomography was used to examine the hard palate and infraorbital groove morphology in Poelagus (Leporidae) and Ochotona. Scans revealed the course and contacts of the canal behind the premolar foramen and structural differences between the two crown clades. We propose that the premolar foramen has evolved independently in several lineages of Lagomorpha, and we discuss development and function of this foramen in the lagomorph skull. This study shows the importance of comprehensive studies on phylogenetically informative non-dental characters in Lagomorpha.
Fluvial terraces of the northwest Iberian lower Miño River.
Viveen, W. ; Schoorl, J.M. ; Veldkamp, A. ; Balen, R.T. van; Vidal-Romani, J.R. - \ 2013
Journal of Maps 9 (2013)4. - ISSN 1744-5647 - p. 513 - 522.
sea-level change - tectonic activity - portugal - uplift - climate - reconstruction - pleistocene - evolution - incision - deposits
A new fluvial terrace map with a tectonic framework for the northwest Iberian lower Miño River is presented. It is the first integrated map to cover the entire lower, 67-km reach of the Miño River, and to cover both the Spanish and Portuguese side of the river. The map is presented at a scale of 1:200,000, although its features were mapped at a scale of 1:5000. Various map layers can be viewed, such as a digital elevation model (DEM), fluvial sediment thickness layers, a palaeoflow direction layer, a lineament and fault layer, and two terrace and tectonic basin layers, showing up to 10 fluvial terraces and a floodplain level. Interpretation of the map shows that next to regional tectonic uplift and glacioeustacy, local basin subsidence and small-scale block movement are very important for the fluvial network, localised fluvial terrace formation, and preservation.
Upstream and downstream controls of recent avulsions on the Taquari megafan, Pantanal, south-western Brazil
Makaske, B. ; Maathuis, B.H.P. ; Padovani, C.R. ; Stolker, C. ; Mosselman, E. ; Jongman, R.H.G. - \ 2012
Earth Surface Processes and Landforms 37 (2012)12. - ISSN 0197-9337 - p. 1313 - 1326.
rhine-meuse delta - upper columbia river - british-columbia - channel belts - bighorn basin - netherlands - floodplain - deposits - architecture - aggradation
Avulsion, the natural relocation of a river, is a key process in the evolution of subaerial fans, river floodplains and deltas. The causes of avulsion are poorly understood, which is partly due to the scarcity of field studies of present avulsions. At present, two avulsions are occurring on the middle and lower Taquari megafan, Pantanal basin, south-western Brazil. Here we present an analysis of the causes of these avulsions based on field and remote sensing data and show that avulsions on megafans can be controlled by both upstream and downstream processes. The middle fan avulsion (started in 1997–1998) is a result of upstream control: overbank aggradation was caused by the (variable) input of sandy sediment into the system, which caused channel-belt superelevation and also created an easily erodible subsurface favouring bank retreat, crevassing, and scour of deep floodplain channels. The sandy subsurface in this area is inferred to have been a major factor in the causation of this avulsion under conditions of little gradient advantage. The lower fan avulsion (started c. 1990) results from interplay of upstream and downstream controls, the latter being related to the local base level (the Paraguay River floodplain) at the toe of the fan. Channel and overbank aggradation on the lower fan was influenced by fan sub-lobe progradation and channel backfilling. Fan sub-lobe progradation caused a significant gradient advantage of the avulsion channel over the parent channel. Avulsions are commonly supposed to be preferentially triggered by high-magnitude floods, when there is considerable channel-belt superelevation. However, both avulsions studied by us were triggered by small to average floods, with modest channel-belt superelevation. We conclude that flood magnitude and channel-belt superelevation have been overrated as causes of avulsion, and demonstrate additional causes that influence the growth of crevasses into avulsions.
Assessment of recent tectonic activity on the NW Iberian Atlantic Margin by means of geomorphic indices and field studies of the lower Miño River terraces
Viveen, W. ; Balen, R.T. van; Schoorl, J.M. ; Veldkamp, A. ; Temme, A.J.A.M. ; Vidal-Romani, J.R. - \ 2012
Tectonophysics 544-545 (2012). - ISSN 0040-1951 - p. 13 - 30.
northwest spain - drainage-basin - galicia - stratigraphy - deposits - example - stress
Until recently, NW Iberia was assumed to be tectonically quiescent (stable). However, a combination of tectono-morphological analyses demonstrates that neotectonic movements do occur, which are in agreement with recent findings by other workers. We use a DEM-based tectono-geomorphic approach in combination with field work to assess the presence and nature of neotectonics in the Lower Miño catchment in NW Iberia. The area is characterized by clearly developed lineaments, coinciding with Paleozoic and Mesozoic faults and fractures and remnants of a peneplain stepping down towards the coast. Longitudinal river profiles show knick points where lithological control can be excluded. Valley shapes show that some valleys have recently been rejuvenated. Systematic asymmetry tendencies of river catchments indicate tilting of fault-bounded blocks. Finally, at several locations faulted terrace deposits of the Miño River have been found. The types of motions that can clearly be evidenced by our analyses are normal faulting and tilting of fault-bounded blocks. Little clear evidence exists for strike-slip faulting, whereas reverse faulting has not been found in this study. A striking morphological feature of the study area is the presence of small fault-bounded basins, along the course of the river Miño. The tectonic movements take place along inherited, Paleozoic and Mesozoic faults, which apparently act as weakness zones. The reactivation of these faults under the present-day stress-conditions is probably the reason for the complicated pattern and style of present-day tectonic motions that we find. The small basins are particularly difficult to explain. They could result from the interaction of partially, obliquely reactivated strike-slip faults (step-over) and normal faults. --------------------------------------------------------------------------------
The Age and Origin of the Gelderse IJssel
Makaske, B. ; Maas, G.J. ; Smeerdijk, D.G. van - \ 2008
Netherlands journal of geosciences 87 (2008)4. - ISSN 0016-7746 - p. 323 - 337.
geologische sedimentatie - geologie - geschiedenis - rivieren - historische geografie - ijssel - gelderland - geological sedimentation - geology - history - rivers - historical geography - river ijssel - gelderland - rhine-meuse delta - wetland woods - netherlands - avulsion - deposits - architecture - excavation - stadshagen - woodlands
Historic trading cities are located on the Gelderse IJssel and flourished in the late Middle Ages. Little is known about this river in the early Middle Ages and before, and there is considerable debate on the age and origin of the Gelderse IJssel as a Rhine distributary. A small river draining the surrounding Pleistocene uplands must have been present in the IJssel valley during most of the Holocene, but very diverse opinions exist as to when this local river became connected to the Rhine system (and thereby to a vast hinterland), and whether this was human induced or a natural process. We collected new AMS radiocarbon evidence on the timing of beginning overbank sedimentation along the lower reach of the Gelderse IJssel. Our data indicate onset of overbank sedimentation at about 950 AD in this reach. We attribute this environmental change to the establishment of a connection between the precursor of the IJssel and the Rhine system by avulsion. Analysis of previous conventional radiocarbon dates from the upper IJssel floodplain yields that this avulsion may have started ~600 AD. Our results contradict earlier suppositions, based on interpretation of archaeological data and historical accounts, that the Gelderse IJssel is much older and originated as a canal, dug under supervision of the Roman general Drusus
The Gelderse IJssel is the third major distributary of the Rhine in the Netherlands and diverts on average similar to 15% of the Rhine discharge northward. Historic trading cities are located on the Gelderse IJssel and flourished in the late Middle Ages. Little is known about this river in the early Middle Ages and before, and there is considerable debate on the age and origin of the Gelderse IJssel as a Rhine distributary. A small river draining the surrounding Pleistocene uplands must have been present in the IJssel valley during most of the Holocene, but very diverse opinions exist as to when this local river became connected to the Rhine system (and thereby to a vast hinterland), and whether this was human induced or a natural process. We collected new AMS radiocarbon evidence on the timing of beginning overbank sedimentation along the lower reach of the Gelderse IJssel. Our data indicate onset of overbank sedimentation at about 950 AD in this reach. We attribute this environmental change to the establishment of a connection between the precursor of the IJssel and the Rhine system by avulsion. Analysis of previous conventional radiocarbon dates from the upper IJssel floodplain yields that this avulsion may have started similar to 600 AD. Our results contradict earlier suppositions, based on interpretation of archaeological data and historical accounts, that the Gelderse IJssel is much older and originated as a canal, dug under supervision of the Roman general Drusus.
New groundwater-level rise data from the Rhine-Meuse delta - implications for the reconstruction of Holocene relative mean sea-level rise and differential land-level movements
Berendsen, H.J.A. ; Makaske, B. ; Plassche, O. van de; Ree, M.H.M. ; Das, S. ; Dongen, M. van; Ploumen, S. ; Schoenmakers, W. - \ 2007
Netherlands journal of geosciences 86 (2007)4. - ISSN 0016-7746 - p. 333 - 354.
geologie - grondwaterstand - bodemdaling - zeespiegelschommelingen - alblasserwaard - zuidhollandse eilanden - zuid-holland - geology - groundwater level - subsidence - sea level fluctuations - alblasserwaard - zuidhollandse eilanden - zuid-holland - western netherlands - flevo lagoon - evolution - bc - avulsion - deposits - coast - area
We present new local groundwater-level rise data from two Late Glacial aeolian dunes, located near Barendrecht and Oud-Alblas in the western Rhine-Meuse delta. These data are based on AMS radiocarbon dating of terrestrial macrofossils, collected from the base of peat formed on the slopes of these dunes. This method avoids contamination of bulk peat samples by old soil carbon or younger rootlets and rhizomes, as well as the hardwater effect. The new data are used to assess the reliability of previously published groundwater-level index data based on conventional radiocarbon dating of bulk basal peat samples from the slopes of the Late Glacial aeolian dunes at Barendrecht, Hillegersberg, Bolnes and Wijngaarden, all located in the western Rhine-Meuse delta. Comparison of the new and published groundwater-level data shows no significant systematic difference between conventionally dated bulk peat samples and AMS-dated samples of terrestrial macrofossils. The new data from the dune at Barendrecht confirm the reliability of the younger than 6600 cal yr BP age-depth data from the dunes at Hillegersberg and near Bolnes. This result supports the validity of this part of the mean sea-level (MSL) curve for the western Netherlands. Consequently, the position of the groundwater-level curve for Flevoland (central Netherlands) below this MSL curve can most likely be attributed to differential land-level movement. The available data show that the groundwater-gradient effect in the western Rhine-Meuse delta became less than 5 cm/km after 6600 calyr BP. Finally, temporal correlation between temporary increases in local groundwater-level rise with known shifts of river courses in the delta plain suggests, that avulsions can explain sudden local deviations from the trend in groundwater-level rise. A general conclusion of this study is that a complex relationship exists between sea level and local delta-plain water levels.
Muddy lateral accretion and low stream power in a sub-recent confined channel belt, Rhine-Meuse delta, central Netherlands
Makaske, B. ; Weerts, H.J.T. - \ 2005
Sedimentology 52 (2005)3. - ISSN 0037-0746 - p. 651 - 668.
concave-bank benches - floodplain formation - british-columbia - river - classification - deposits - canada - sedimentology - area
The Hennisdijk fluvial system in the central Rhine-Meuse delta is an abandoned Rhine distributary that was active on a wide floodplain from 3800 to 3000 years BP. Cross-sectional geometry, lithological characteristics and planform patterns of the channel-belt deposits indicate lateral migration of the Hennisdijk palaeochannel. Channel-belt deposits are around 10 m thick and 200¿400 m wide. A gravelly facies near the base of the channel-belt deposits represents channel-lag and lower point-bar deposits. The axis of the channel belt is dominated by a sandy facies (medium and coarse sand), showing an overall fining upward trend with multiple cycles. This facies is interpreted as lower and middle point-bar deposits. The sandy facies is capped by a muddy facies, which is 1¿2 m thick near the axis of the channel belt and thickens to 5¿6 m along the margins. It laterally interfingers with the sandy facies that occurs near the channel-belt axis, but it has sharp, erosive outer contacts marking the edges of the channel belt. The muddy facies comprises inclined heterolithic stratification (IHS) (fine/medium sand¿mud couplets) in its upper part. The relatively thin muddy facies with IHS that occurs near the channel-belt axis is interpreted as upper point-bar deposits with lateral accretion surfaces, formed under marine influence. Along the margins of the channel belt the muddy facies consists of thick, fairly homogeneous, successions of mud with variable sand content, and fine sand. Based on facies geometry and position, this part of the muddy facies is interpreted as counterpoint deposits, formed along the upstream limb of the concave bank of a channel bend. Counterpoint accretion seems to have been associated with the confined nature of the channel belt, which was the result of low stream power (4·5¿7·8 W m2, based on reconstructions of palaeodischarge and channel slope) and cohesive bank material, i.e. clayey floodbasin deposits with intercalated peat beds occurring next to the channel belt. In the literature, counterpoint accretion is mostly reported from alluvial valleys, where meandering is confined by limited floodplain width, whereas muddy lateral accretion surfaces are commonly reported from much wider marine-influenced floodplains. The present study shows juxtaposition of both forms of muddy channel deposits in a low-energy, wide coastal plain setting, where preservation potential is considerable.