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1.
Tomasz Salamon Tomasz Zieli&#x;ski 《Boreas: An International Journal of Quaternary Research》2019,48(3):695-712
In this paper, fluvial deposits of Middle Pleistocene age in the mountain‐foreland area of southern Poland (Eastern Sudetes and Western Carpathians) are studied in order to document the evolution of fluvial systems during the coldest stages of glacial periods when the Scandinavian Ice Sheet advanced far to the south. The focus is on fluvial response to climate change and glacial impact on river system behaviour. Also considered is the tectonic uplift of the mountain part of river catchments and its potential influence on the style of fluvial sedimentation in the fore‐mountain area. Three drainage basins that were active during the Elsterian and Saalian glaciations are investigated. Facies analyses are carried out on thick successions of braided river deposits covered with till or glaciolacustrine sediments, which result in a reconstruction of the fluvial activity synchronous with the ice‐sheet advance. The results suggest that fluvial activity declined prior to ice‐sheet advance into the fore‐mountain area. This climatically induced change is directly recorded in alluvial successions by upward‐decreasing bed thicknesses and grain sizes. River longitudinal profiles were shortened in front of the advancing ice sheet. The base level of the studied rivers, created by the ice‐sheet margin, rose in parallel with glacial advance. As a result, the successive reaches of rivers (degradational, transitional, aggradational) underwent shortening and moved upstream within the catchments. Moreover, tectonically induced local increases of river slopes may have influenced the depositional processes. 相似文献
2.
Stream profile analysis of the Koralm Range (Eastern Alps) 总被引：1，自引：0，他引：1
3.
From source terrains of the Eastern Alps to the Molasse Basin: Detrital record of non-steady-state exhumation 总被引：2，自引：1，他引：2
Fission-track cooling ages of detrital apatite (AFT) in the East Alpine Molasse Basin display age groups corresponding to geodynamic events in the orogen since Jurassic times. These age groups are typical of certain thermotectonic units, which formed a patchwork in the Swiss and Eastern Alps. By a combination of petrographic and thermochronologic data, progressive erosion of source terrains is monitored in different catchments since the Oligocene. The AFT cooling ages show a decrease in lag time until when rapidly cooled debris derived from tectonically exhumed core complexes became exposed. After termination of tectonic exhumation, lag times of debris derived from the core complexes increased. Neither on the scale of the entire Eastern Alps, or on the scale of individual catchments, steady-state exhumation is observed, due to the highly dynamic changes of exhumation rates since Late Eocene collision. 相似文献
4.
The Alpine drainage system comprises two large orogen-parallel drainage basins in the core of the Alps (the Rhone and Rhine valleys), and smaller orogen-normal orientated systems. Discharge of the large rivers is ≈5–10 higher than that of the small ones. In addition, the courses of the Rhone and Rhine Rivers are trapped by faults and thrusts that display lower erosional resistance than the neighbouring lithologies. Enhanced discharge of these rivers and the low erosional resistance of their bedrocks potentially enhances surface erosion. Indeed, present-day and glacial sediment yields are ≈1.6–1.7 times higher in these valleys than in the orogen-normal systems. Interestingly, rates of crustal uplift are also enhanced in the Rhine and Rhone valleys, where current rates of ≈1.4–1.6 mm yr−1 are measured. The spatial coincidence between the location of enhanced erosion and maximum crustal uplift rates are interpreted to reflect a positive feedback between surface erosion and tectonic forcing. 相似文献
5.
The glacial history of the Tagliamento morainic amphitheater (southeastern Alpine foreland, Italy) during the last glacial maximum (LGM) has been reconstructed by means of a geological survey and drillings, radiocarbon dating and pollen analysis in the amphitheater and in the sandur. Two phases of glacial culmination, separated by a distinct recession, are responsible for glacial landforms and related sediments in the outer part of the amphitheater. The age of the younger advance fits the chronology of the culmination of the last glaciation in the Alps, well established between 24 and 21 cal ka BP (20 to 17.5 14C ka BP), whereas the first pulse between 26.5 and 23 cal ka BP (22 to 21 14C ka BP), previously undated, was usually related to older (pre-LGM) glaciations by previous authors. Here, the first pulse is the most extensive LGM culmination, but is often buried by the subsequent pulse. The onset and final recession of the late Würm Alpine glaciation in the Tagliamento amphitheater are synchronous with the established global glacial maximum between 30 and 19 cal ka BP. The two-fold LGM glacial oscillation is interpreted as a millennial-scale modulation within the late Würm glaciation, caused by oscillations in inputs of southerly atmospheric airflows related to Dansgaard-Oeschger cycles. Phases of enhanced southerly circulation promoted increased rainfall and ice accumulation in the southern Alps. 相似文献
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7.
中国第四纪冰川研究的现状与争议——兼记首届“中国第四纪冰川与环境变化”研讨会 总被引：3，自引：3，他引：0
冰川是塑造地表形态最积极的外营力之一, 对第四纪冰期与间冰期旋回中冰川进退留下的丰富且形态独特的冰川地形的研究, 不仅能重建古冰川时空演化的规律, 在构造活跃的山区还可为山体抬升提供重要的理论参考. 2012年8月, 中国从事冰川地貌与环境变化研究的学者相聚兰州, 总结了以技术定年为主要特征的第四纪冰川研究新阶段取得的成绩与突破, 并探讨了现阶段工作的重点及未来的发展方向. 与会代表认为, 可对冰川地形进行直接定年的测年技术的发展与应用, 促进了我国第四纪冰川研究的发展, 现阶段及今后应着重加强与开展如下几个方面工作: 1)精确年代学框架的建立是现阶段我国第四纪冰川研究的重点; 2)青藏高原及周边山地最老冰碛的追溯及其年代测定是回答我国第四纪冰川开始发育的关键, 也是理解青藏高原构造抬升与冰期气候耦合的内在要求; 3)我国东部(105° E以东)第四纪冰川与环境问题需作进一步的研究与澄清, 科普工作亟待加强. 相似文献
8.
The stream power model was applied to Lushan Mt. in South China in order to verify its capability of interpreting the uplift of a small block mountain. On a log-log plot, the longitudinal profiles of 9 rivers derived from a 30m DEM exhibit primary characteristics similar to those derived from a 5m DEM; however, the 5m DEM clearly reveals more minor knickpoints, and the positions of knickpoints are pinpointed more accurately. All of the studied rivers on the block mountain are in a transient state due to geological perturbations. Some of them exhibit two segments in steady state separated by a slope-break knickpoint. Such rivers generally develop in a longitudinal valley, which are less perturbed by substrate inhomogeneities. The similar heights of the slope-break knickpoints and the similar uplift rate indicated by the ksn values demonstrate an almost simultaneous headward erosion induced by the fall in base level. This modelling result is consistent with the mode of formation of this particular block mountain. Our study demonstrates that the stream power model is applicable to a small tectonically-active massif only if the channel segments are in a steady state. 相似文献
9.
Sara Picone Francesca Alvisi Enrico Dinelli Caterina Morigi Alessandra Negri Mariangela Ravaioli Carmela Vaccaro 《第四纪科学杂志》2008,23(5):489-501
Sedimentological, geochemical and micropalaeontological data from sediment cores in the northwestern Adriatic Sea were obtained to reconstruct the stratigraphic framework and palaeogeographic setting during the last post‐glacial sea‐level rise (14000–6000 yr BP). Four lithostratigraphic units were identified: (a) distal plain deposits (>14000 yr BP), submerged during the first phases of marine ingression; (b) coastal lagoon system; (c) barrier‐lagoon system, which is dated back to between 10019 ± 61 and 10228 ± 174 cal. yr BP from 14C dating on peat and shell remains; (d) marine prodelta deposits (<5500 yr BP). Geochemical data allow the identification of three distinct sediment sources: River Po, River Adige and Eastern Alpine rivers characterised by decreasing Ni/Mg ratios (50–70, 8–15 and 5–10, respectively) and Ba/Al ratios of 45–55, 55–65 and 35–45, respectively. The three sources display different relative abundances in time. During the Lateglacial, the Po is the main sediment source for the southern cores, whereas the Eastern Alps and the River Adige are the main sediment sources for the northern cores. This suggests a northern position of the Po River bed compared to previous studies. Coastal drowning led to a homogenization of the provenance signal within the sediments. Only after the marine transgression does a River Po signal appear in the northern cores. At the same time, in the southern cores the signal of Eastern Alpine rivers becomes stronger. Transgressive barrier‐lagoon and recent sediments do not display a predominant signal for provenance indicators. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
Balancing lateral orogenic float of the Eastern Alps 总被引：2，自引：0，他引：2
Hans-Gert Linzer Kurt Decker Herwig Peresson Rudi Dell'Mour Wolfgang Frisch 《Tectonophysics》2002,354(3-4)
Oligocene to Miocene post-collisional shortening between the Adriatic and European plates was compensated by frontal thrusting onto the Molasse foreland basin and by contemporaneous lateral wedging of the Austroalpine upper plate. Balancing of the upper plate shortening by horizontal retrodeformation of lateral escaping and extruding wedges of the Austroalpine lid enables an evaluation of the total post-collisional deformation of the hangingwall plate. Quantification of the north–south shortening and east–west extension of the upper plate is derived from displacement data of major faults that dissect the Austroalpine wedges. Indentation of the South Alpine unit corresponds to 64 km north–south shortening and a minimum of 120 km of east–west extension. Lateral wedging affected the Eastern Alps east of the Giudicarie fault. West of the Giudicarie fault, north–south shortening was compensated by 50 to 80 km of backthrusting in the Lombardian thrust system of the Southern Alps. The main structures that bound the escaping wedges to the north are the Inntal fault system (ca. 50 km sinistral offset), the Königsee–Lammertal–Traunsee (KLT) fault (10 km) and the Salzach–Ennstal–Mariazell–Puchberg (SEMP) fault system (60 km). These faults, as well as a number of minor faults with displacements less than 10 km, root in the basal detachment of the Alps. The thin-skinned nature of lateral escape-related structures north of the SEMP line is documented by industry reflection seismic lines crossing the Northern Calcareous Alps (NCA) and the frontal thrust of the Eastern Alps. Complex triangle zones with passive roof backthrusts of Middle Miocene Molasse sediments formed in front of the laterally escaping wedges of the northern Eastern Alps. The aim of this paper is a semiquantitative reconstruction of the upper plate of the Eastern Alps. Most of the data is published elsewhere. 相似文献
11.
Post-glacial tectonic faults in the eastern Swiss Alps occur as single lineaments, clusters of faults or extensive fault zones consisting of several individual faults aligned along the same trend. The orientation of the faults reflects the underlying lithology and the pre-existing structures (joints, pervasive foliations) within these lithologies. Most post-glacially formed faults in the area around Chur, which undergoes active surface uplift of 1.6 mm/year, trend E–W and cut across Alpine and glacial features such as active screes and moraines. Additionally, there are NNW and ENE striking faults reactivating pervasive Alpine foliations and shear zones. Based on a comparison with the nodal planes of recent earthquakes, E–W striking faults are interpreted as active faults. Because of very short rupture lengths and mismatches of fault location with earthquake distribution, magnitude and abundance, the faults are considered to be secondary faults due to earthquake shaking, cumulative deformation in post- or interseismic periods or creep, and not primary earthquake-related faults. The maximum of recent surface uplift rates coincides with the youngest cooling of the rocks according to apatite fission-track data and is therefore a long-lived feature that extends well into pre-glacial times. Isostatic rebound owing to overthickened crust or to melting of glacial overburden cannot explain the observed surface uplift pattern. Rather, the faults, earthquakes and surface uplift patterns suggest that the Alps are deforming under active compression and that the Aar massif basement uplift is still active in response to ongoing collision. 相似文献
12.
Lothar Ratschbacher Christian Dingeldey Christine Miller Bradley R. Hacker Michael O. McWilliams 《Tectonophysics》2004,394(3-4):155-170
New 40Ar/39Ar geochronology places time constraints on several stages of the evolution of the Penninic realm in the Eastern Alps. A 186±2 Ma age for seafloor hydrothermal metamorphic biotite from the Reckner Ophiolite Complex of the Pennine–Austroalpine transition suggests that Penninic ocean spreading occurred in the Eastern Alps as early as the Toarcian (late Early Jurassic). A 57±3 Ma amphibole from the Penninic subduction–accretion Rechnitz Complex dates high-pressure metamorphism and records a snapshot in the evolution of the Penninic accretionary wedge. High-pressure amphibole, phengite, and phengite+paragonite mixtures from the Penninic Eclogite Zone of the Tauern Window document exhumation through ≤15 kbar and >500 °C at 42 Ma to 10 kbar and 400 °C at 39 Ma. The Tauern Eclogite Zone pressure–temperature path shows isothermal decompression at mantle depths and rapid cooling in the crust, suggesting rapid exhumation. Assuming exhumation rates slower or equal to high-pressure–ultrahigh-pressure terrains in the Western Alps, Tauern Eclogite Zone peak pressures were reached not long before our high-pressure amphibole age, probably at ≤45 Ma, in accordance with dates from the Western Alps. A late-stage thermal overprint, common to the entire Penninic thrust system, occurred within the Tauern Eclogite Zone rocks at 35 Ma. The high-pressure peak and switch from burial to exhumation of the Tauern Eclogite Zone is likely to date slab breakoff in the Alpine orogen. This is in contrast to the long-lasting and foreland-propagating Franciscan-style subduction–accretion processes that are recorded in the Rechnitz Complex. 相似文献
13.
Structure of the lithosphere beneath the Eastern Alps (southern sector of the TRANSALP transect) 总被引：1，自引：0，他引：1
Alberto Castellarin Rinaldo Nicolich Roberto Fantoni Luigi Cantelli Mattia Sella Luigi Selli 《Tectonophysics》2006,414(1-4):259
The interpretation of the seismic Vibroseis and explosive TRANSALP profiles has examined the upper crustal structures according to the near-surface geological evidences and reconstructions which were extrapolated to depth. Only the southern sector of the TRANSALP transect has been discussed in details, but its relationship with the whole explored chain has been considered as well. The seismic images indicate that pre-collision and deep collision structures of the Alps are not easily recognizable. Conversely, good records of the Neo-Alpine to present architecture were provided by the seismic sections.Two general interpretation models (“Crocodile” and “Extrusion”) have been sketched by the TRANSALP Working Group [2002]. Both illustrate the continental collision producing strong mechanical interaction of the facing European and African margins, as documented by giant lithosphere wedging processes. Arguments consistent with the “Extrusion” model and with the indentation of Adriatic (Southalpine) lithosphere underneath the Tauern Window (TW) are:
- – According to the previous DSS reconstructions, the Bouguer anomalies and the Receiver Functions seismological data, the European Moho descends regularly attaining a zone south of the Periadriatic Lineament (PL). The Moho boundary and its geometry appear to be rather convincing from images of the seismic profile;
- – the Tauern Window intense uplift and exhumation is coherent with the strong compression regime, which acted at depth, thus originating the upward and lateral displacement of the mobile and ductile Penninic masses according to the “Extrusion” model;
- – the indentation of the Penninic mobile masses within the colder and more rigid Adriatic crust cannot be easily sustained. Wedging of the Adriatic stiffened lower crust, under high stresses and into the weaker Penninic domain, can be a more suitable hypothesis. Furthermore, the intrusion of the European Penninic crustal wedge underneath the Dolomites upper crust is not supported by any significant uplifting of the Dolomites. The total average uplift of the Dolomites during the Neogene appears to be 6−7 times smaller than that recognized in the TW. Markedly the northward dip of the PL, reaching a depth of approximately 20 km, is proposed in our interpretation;
- – finally, the Adriatic upper crustal evolution points to the late post-collision change in the tectonic grow-up of the Eastern Alps orogenic chain. The tectonic accretion of the northern frontal zone of the Eastern and Central Alps was interrupted from the Late Miocene (Serravallian–Tortonian) onward, as documented by the Molasse basin evolution. On the contrary, the structural nucleation along the S-vergent tectonic belt of the eastern Southern Alps (Montello–Friuli thrust belt) severely continued during the Messinian and the Plio–Pleistocene. This structural evolution can be considered to be consistent with the deep under-thrusting and wedge indentation of the Adriatic lithosphere underneath the southern side of the Eastern Alps thrust-and-fold belt.
14.
《Journal of Asian Earth Sciences》1999,17(3):307-318
Research into the Quaternary geology of the NW Himalaya has concentrated on the elucidation of the glacial sequence. However, whilst the main ranges of the Himalaya have been subjected to numerous glaciations and are now an obvious alpine glaciated terrain, much of the landscape in Zanskar and Ladakh is more equivocal and does not appear to have been glaciated during this time. These landscape facets may therefore have a much older origin and relate to preglacial events.In Zanskar, the main ice source in all glaciations was the strongly glaciated and still glacierized north slope of the main Himalaya. This ice then flowed generally northwards in the valleys of the Zanskar river and its tributaries leaving between them a landscape supporting only a few and scattered minor local glaciers. Evidence of early glaciation has been found on isolated valley-side remnants >200 m above the present rivers. Reconstruction of these preglacial valley cross profiles show them to be generally broad and shallow, with gentle slopes. This is in distinct contrast to the present major valley systems which can usually be divided into two parts—a lower unglaciated fluvially eroded section, such as the Lungnak (Tsarap Lingti Chu) Gorge and an upper broad glacial section, such as the Stod (Doda) valley.Down-valley extent of glaciation is defined by the upper ends of unglaciated fluvial gorges. Laterally, the glaciers were confined progressively to their valleys. Inevitably there is only evidence of successively smaller subsequent glaciations, but the tectonic uplift of the southern ranges may have been a factor in this forming an increasing barrier to the snow-bearing monsoon winds. 相似文献
15.
The three-dimensional (3D) lithospheric density structure of the Eastern Alps was investigated by integrating results from reflection seismics, receiver function analyses and tomography. The modelling was carried out with respect to the Bouguer gravity and the geoid undulations and emphasis were laid on the investigations of the importance of deep lithospheric features. Although the influence of inhomogeneities at the lithosphere–asthenosphere boundary on the potential field is not neglectable, they are overprinted by the response of the density contrast at the crust–mantle boundary and intra-crustal density anomalies. The uncertainties in the interpretations are in the same order of magnitude as the gravity field generated by the deep lithosphere.After including the deep lithospheric geometry from the tomographic model it is shown that full isostatic equilibrium is not achieved below the Eastern Alps. However, calculation of the isostatic lithospheric thickness shows two areas of lithospheric thickening along the central axis of the Eastern Alps with a transition zone below the area of the TRANSALP profile. This is in agreement with the tomographic model, which features a change in lithospheric subduction direction. 相似文献
16.
Hans Petter Sejrup Eiliv Larsen Haflidi Haflidason Ida M. Berstad Berit O. Hjelstuen Hafdis E. Jonsdottir Edward L. King Jon Landvik Oddvar Longva Atle Nygrd Dag Ottesen Stle Raunholm Leif Rise Knut Stalsberg 《Boreas: An International Journal of Quaternary Research》2003,32(1):18-36
The Norwegian Channel between Skagerrak, in the southeast, and the continental margin of the northern North Sea, in the northwest, is the result of processes related to repeated ice stream activity through the last 1.1 m yr. In such periods the Skagerrak Trough (700 m deep) has acted as a confluence area for glacial ice from southeastern Norway, southern Sweden and parts of the Baltic. Possibly related to the threshold in the Norwegian Channel off Jæren (250 m deep), the ice stream, on a number of occasions over the last 400 ka, inundated the coastal lowlands and left an imprint of NW‐oriented ice directional features (drumlins, stone orientations in tills and striations). Marine interstadial sediments found up to 200 m a.s.l. on Jæren have been suggested to reflect glacial isostasy related to the Norwegian Channel Ice Stream (NCIS). In the channel itself, the ice stream activity is evidenced by mega‐scale glacial lineations on till surfaces. As a result of subsidence, the most complete sedimentary records of early phases of the NCIS are preserved close to the continental margin in the North Sea Fan region. The strongest evidence for ice stream erosion during the last glacial phase is found in the Skagerrak. On the continental slope the ice stream activity is evidenced by the large North Sea Fan, which is mainly a result of deposition of glacial‐fed debris flows. Northwards of the North Sea Fan, rapid deposition of meltwater plume deposits, possibly related to the NCIS, is detected as far north as the Vøring Plateau. The NCIS system offers a unique possibility to study ice stream related processes and the impact the ice stream development had on open ocean sedimentation and circulation. 相似文献
17.
Karl Brunnacker Manfred Löscher Wolfgang Tillmanns Brigitte Urban 《Quaternary Research》1982,18(2):152-173
Thirteen glacial terraces are known from the western part of the northern Alpine foothills between the Lech and Iller Rivers. In the Lower Rhine region of West Germany, a similar number of terraces are capped by interglacial floodloams and soils. Whereas the environment during individual interglaciations did not differ substantially, the glaciations were progressively more severe. The Main Terrace system of the Rhine may be an exception. The duration of the Quaternary, starting at the base of Praetiglian, is estimated at approximately 2 million yr by paleomagnetic dating. The major cold-warm climatic cycles of the earliest Pleistocene lasted approximately 100,000 yr, the same as those of the Brunhes Chron. The intervening Main Terrace system has not yet been climatically subdivided. Correlation with the Netherlands is possible because of an abundance of paleobotanic and paleomagnetic evidence. In the Alpine foothills, stratigraphically useful indicators of warm climates are missing, but analogies in terrace development permit comparison with the Lower Rhine and Danube. The terrace sequence in the Alpine foothills is incomplete, as are those along most of the other rivers in Europe. Some of the older terraces may have been eroded. 相似文献
18.
19.
Paleomagnetic evidence for large en-bloc rotations in the Eastern Alps during Neogene orogeny 总被引：2，自引：0，他引：2
We present new paleomagnetic data from the Northern Calcareous Alps and the Central Alps of Austria. All new data are overprint magnetizations and can be subdivided into two groups: In rocks older than earliest Rupelian, two remagnetizations reflecting both clockwise and counter-clockwise rotation were detected. In rocks of late Rupelian and younger ages, only a counter-clockwise rotated remagnetization was found. Our results together with results from previous paleomagnetic studies from the Eastern and Southern Alps suggest two main phases of vertical axis rotation. The first, clockwise rotation affecting the Northern Calcareous Alps was active between earliest to Late Rupelian. We propose a model where the Northern Calcareous Alps are segmented into individual blocks. Within a dextral shear corridor these blocks rotated clockwise due to the counter-clockwise rotation of the Southern Alps and Central Alps. The second, counter-clockwise rotation occurred in the Late Oligocene to Middle Miocene, affecting Eastern and Southern Alps. In this stage of orogeny, the internal massifs of the Western Alps were already accreted to the upper plate and therefore included in counter-clockwise rotation. This rotation is contemporaneous with counter-clockwise rotation in the Apennines and opening of the Balearic basin, and a genetic relationship is suggested. A second step of counter-clockwise rotation, reconstructed from published data, is observed in the sedimentary basins at the southeastern margin of the Eastern Alps, where counter-clockwise rotated Miocene and Pliocene sedimentary rocks are present. This rotation is seen in connection to a young counter-clockwise rotation of the Adriatic plate. 相似文献
20.
The configuration of Alpine accumulation areas during the last glacial maximum (LGM) has been reconstructed using glacial–geological mapping. The results indicate that the LGM ice surface consisted of at least three major ice domes, all located south of the principal weather divide of the Alps. This implies that the buildup of the main Alpine ice cover during oxygen isotope stage (OIS) 2 was related to precipitation by dominant southerly atmospheric circulation, in contrast to today's prevalent westerly airflow. Such a reorganization of the atmospheric circulation is consistent with a southward displacement of the Oceanic Polar Front in the North Atlantic and of the associated storm track to the south of the Alps. These results, combined with additional paleoclimate records from western and southern Europe, allow an interpretation of the asynchronous evolution of the different European ice caps during the last glaciation. δ18O stages (OIS) 4 and 3 were characterized by location of the Polar Front north of 46°N (Gulf of Biscay). This affected prevailing westerly circulation and, thus, ice buildup in western Scandinavia, the Pyrénées, Vosges, and northern Alps. At the LGM, however, the Polar Front lay at 44°N, causing dominating southerly circulation and reduced precipitation in central and northern Europe. 相似文献