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1.
We measured in situ cosmogenic 10Be in 16 bedrock and 14 boulder samples collected along a 40-km transect outside of and normal to the modern ice margin near Sikuijuitsoq Fjord in central-west Greenland (69°N). We use these data to understand better the efficiency of glacial erosion and to infer the timing, pattern, and rate of ice loss after the last glaciation. In general, the ages of paired bedrock and boulder samples are in close agreement (r2 = 0.72). Eleven of the fourteen paired bedrock and boulder samples are indistinguishable at 1σ; this concordance indicates that subglacial erosion rates are sufficient to remove most or all 10Be accumulated during previous periods of exposure, and that few, if any, nuclides are inherited from pre-Holocene interglaciations. The new data agree well with previously-published landscape chronologies from this area, and suggest that two chronologically-distinct land surfaces exist: one outside the Fjord Stade moraine complex (～10.3 ± 0.4 ka; n = 7) and another inside (～8.0 ± 0.7 ka; n = 21). Six 10Be ages from directly outside the historic (Little Ice Age) moraine show that the ice margin first reached its present-day position ～7.6 ± 0.4 ka. Early Holocene ice margin retreat rates after the deposition of the Fjord Stade moraine complex were ～100–110 m yr?1. Sikuijuitsoq Fjord is a tributary to the much larger Jakobshavn Isfjord and the deglaciation chronologies of these two fjords are similar. This synchronicity suggests that the ice stream in Jakobshavn Isfjord set the timing and pace of early Holocene deglaciation of the surrounding ice margin.  相似文献   

2.
The Bayan Har Shan, a prominent upland area in the northeastern sector of the Tibetan Plateau, hosts an extensive glacial geological record. To reconstruct its palaeoglaciology we have determined 10Be exposure ages based on 67 samples from boulders, surface pebbles, and sediment sections in conjunction with studies of the glacial geology (remote sensing and field studies) and numerical glacier modelling. Exposure ages from moraines and glacial sediments in Bayan Har Shan range from 3 ka to 129 ka, with a large disparity in exposure ages for individual sites and within the recognised four morphostratigraphical groups. The exposure age disparity cannot be explained by differences in inheritance without using unrealistic assumptions but it can be explained by differences in post-depositional shielding which produces exposure ages younger than the deglaciation age. We present a palaeoglaciological time-slice reconstruction in which the most restricted glaciation, with glaciers less than 10 km long, occurred before 40–65 ka. More extensive glaciations occurred before 60–100 ka and 95–165 ka. Maximum glaciation is poorly constrained but probably even older. The Bayan Har Shan exposure age dataset indicates that glaciers on the northeastern Tibetan Plateau have remained surprisingly restricted for at least 40 ka, including the global last glacial maximum (LGM). This case of a missing LGM is further supported by high-resolution glacier modelling experiments.  相似文献   

3.
《Geodinamica Acta》2001,14(4):231-263
Erosional denudation of the Alps and their role as sediment source underwent major changes throughout the Quaternary, by repeated glaciation and deglaciation. The sediment fluxes of 16 major Alpine drainage basins were quantified by determining the sediment volumes which have been trapped in valleys and lake basins. These became sedimentologically closed after the last glacier retreat around 17 000 cal. BP. The sediment volumes distributed over their provenance areas yield mean mechanical denudation rates between 250 to 1060 mm ka–1. In contrast, modern denudation rates, derived from river loads and delta surveys, range from 30 to 360 mm ka–1. Relief, such as mean elevation and slope, turned out to be the primary control of both modern and Late Glacial mechanical denudation. Rock types seem to be responsible for some scatter of the data, but their role is masked by other factors. Modern denudation rates increase with higher proportions of bare rocks and glaciated area, but decrease with forest cover. An area-weighted extrapolation of the studied drainage basins to the entire Alps on the basis of major morphotectonic zones yields a mean denudation rate of 620 mm ka–1 over the last 17 000 years. This rate clearly exceeds the modern rate of 125 mm ka–1. Lake sediments and palaeoclimatic reconstructions confirm that the sediment yield of the Alps reached a maximum during deglaciation when large masses of unconsolidated materials were available, vegetation was scarse, and transport capacities were high. During the early Holocene sediment yield declined to a minimum before some climate deterioration and human activities again accelerated erosional processes. Assuming a denudation rate in the early Holocene half of the modern one, the Late Glacial denudation rates must have been in the order of 1100 to 2900 mm ka–1. Consequently, denudation rates during a glacial/interglacial cycle probably varied by a factor of 14, which lies well within the range of other studies in central Europe, Scandinavia and North America. From large scale sediment budgets of perialpine sedimentary basins the overall denudation rate of the Alps during the Quaternary has been c. 400 mm ka–1, i.e. about one third lower than the estimate for the last 17000 years. This can be well explained by the outstanding role which deglaciation played in the time span studied here.  相似文献   

4.
Seismostratigraphical studies of the 11.8‐km2‐large and ~140‐m‐deep Lake Bolshoye Shchuchye, Polar Ural Mountains, reveal up to 160‐m‐thick acoustically laminated sediments in the lake basin. Using a dense grid of seismic lines, the spatial and temporal distributions of the sedimentary history have been reconstructed. Three regional seismic horizons have been identified and correlated with the well‐dated 24‐m‐long sediment core retrieved from the lake. Isopach maps constructed from the seismic data show four phases of sedimentation. A contour map of the deepest regional seismic reflector represents the earliest hemipelagic sedimentation in the lake. Three contour maps represent time intervals covering the last 23 cal. ka based on the well‐dated core stratigraphy from the lake. The detailed time constraints on the upper stratigraphical units in the lake allow calculation of the lake's development in terms of sediment fluxes and the denudation rates from the Last Glacial Maximum (LGM) to the present. The sedimentation in Lake Bolshoye Shchuchye has been dominated by hemipelagic processes during at least the last 24 cal. ka BP only locally interrupted by delta progradation and slope processes. A major shift in the sediment accumulation at c. 18.7 cal. ka BP is interpreted to mark the end of the local glacial maximum, greatly reduced denudation and the onset of the deglaciation period; this also demonstrates how fast the glaciers melted and possibly disappeared at the end of the LGM. The denudation rate during the Holocene is only a fifth of the LGM rate. The age of the oldest stratified sediments in Lake Bolshoye Shchuchye is not well constrained, but estimated as c. 50–60 ka.  相似文献   

5.
Uummannaq Fjord, West Greenland, held the Uummannaq Ice Stream system that drained an estimated ~6% of the Greenland Ice Sheet (GrIS) during the Last Glacial Maximum. Published ages for the final deglaciation in Uummannaq Fjord vary from as early as c. 9.8 ka to as late as c. 5.3 ka. Assessing this variability requires additional chronological controls to improve the deglaciation history of central West Greenland. Here, we combine 14C dating of lake sediment cores with cosmogenic 10Be exposure dating at sites adjacent to the present GrIS margin in the central‐inland sector of the Uummannaq Fjord system. We find that ice retreated to or within the present GrIS margin at 10.8±0.2 ka (n = 6). Although this ‘final deglaciation’ to or within the present GrIS margin across the Uummannaq Fjord system varies from c. 10.8 to 5.3 ka, all chronologies indicate collapse from the continental shelf to the inner fjords at c. 11.0 ka, which occurred at a net retreat rate of 300–1100 m a−1. The Uummannaq Fjord system deglaciated c. 1000 years earlier than the major fjord system to the south, Disko Bugt. However, similarly rapid retreat rates of the two palaeo‐ice stream systems suggest that their collapse may have been aided by high calving rates. The asynchronous deglaciation of the GrIS throughout the Uummannaq Fjord system probably relates to the influence of varying fjord geometry on marine glacier behaviour.  相似文献   

6.
We determined erosion rates on timescales of 101–104 years for two catchments in the northeastern Rhenish Massif, in order to unravel the Quaternary landscape evolution in a Variscan mountain range typical of central Europe. Spatially averaged erosion rates derived from in situ produced 10Be concentrations in stream sediment of the Aabach and M?hne watersheds range from 47 ± 6 to 65 ± 14 mm/ka and integrate over the last 9–13 ka. These erosion rates are similar to local rates of river incision and rock uplift in the Quaternary and to average denudation rates since the Mesozoic derived from fission track data. This suggests that rock uplift is balanced by denudation, i.e., the landscape is in a steady state. Short-term erosion rates were derived from suspended and dissolved river loads subsequent to (1) correcting for atmospheric and anthropogenic inputs, (2) establishing calibration curves that relate the amount of suspended load to discharge, and (3) estimating the amount of bedload. The resulting solid mass fluxes (suspended and bedload) agree with those derived from the sediment volume trapped in three reservoirs. However, resulting geogenic short-term erosion rates range from 9 to 25 mm/ka and are only about one-third of the rates derived from 10Be. Model simulations in combination with published sediment yield data suggest that this discrepancy is caused by at least three factors: (1) phases with higher precipitation and/or lower evapotranspiration, (2) rare flood events not captured in the short-term records, and (3) prolonged periods of climatic deterioration with increased erosion and sediment transport on hillslopes.  相似文献   

7.
Considerable uncertainty surrounds the timing of glacier advance and retreat during the Younger Dryas or Loch Lomond Stade (LLS) in the Scottish Highlands. Some studies favour ice advance until near the end of the stade (c. 11.7 ka), whereas others support the culmination of glacier advance in mid‐stade (c. 12.6–12.4 ka). Most published 10 Be exposure ages reported for boulders on moraines or deglacial sites post‐date the end of the LLS, and thus appear to favour the former view, but recalibration of 33 10 Be ages using a locally derived 10 Be production rate and assuming rock surface erosion rates of zero to 1 mm ka?1 produces exposure ages 130–980 years older than those originally reported. The recalibrated ages are filtered to exclude anomalous data, and then employed to generate aggregate probability density distributions for the timing of moraine deposition and deglaciation. The results suggest that the most probable age for the timing of the deposition of the sampled outermost moraines lies in the interval 12.4–12.1 ka or earlier. Deglacial ages obtained for sites inside Loch Lomond Stadial glacier limits imply that glaciers at some or all of the sampled sites were retreating prior to 12.1 ka. Use of aggregated data does not exclude the possibility of asynchronous glacier behaviour at different sites, but confirms that some glaciers reached their maximum limits and began to retreat several centuries before the rapid warming that terminated the LLS at 11.7–11.6 ka, consistent with the retrodictions of recent numerical modelling experiments and with geomorphological evidence for gradual oscillatory ice‐margin retreat under stadial conditions.  相似文献   

8.
《Quaternary Science Reviews》2007,26(17-18):2185-2200
Taiwan, located at the junction of the Pacific Ocean, the Eurasian continent, and the South China marginal Sea, is of particular interest for reconstructing paleoclimate periods in Eastern Asia. This study reports the first cosmic ray exposure dating (CRE) of glacial features in Taiwan. Among the areas where glacial relicts have been described in Taiwan, the Nanhuta Shan range is probably the place where glacial landforms are best preserved. We consequently focused on this area combining glacial geomorphology observations together with CRE dating using in situ produced 10Be of erratic boulders and ice-sculpted surfaces. When combined with the geomorphic characteristics of the sampled areas, the obtained minimum CRE ages suggest that the glacial retreat in the Nanhuta Shan commenced about 10±3 ka ago and retreat was complete by 7±1 ka ago. This is consistent with the Holocene warming trend deduced from other biological and physico-chemical paleoclimatic records for the region. Estimates of local bedrock surface denudation rates either directly from in situ produced 10Be measurements or from geomorphic considerations are employed to determine the preservation of such glacial features within the highly dynamic setting of Taiwan.  相似文献   

9.
Recent estimates of the timing of the last glaciation in the southern and western Uinta Mountains of northeastern Utah suggest that the start of ice retreat and the climate-driven regression of pluvial Lake Bonneville both occurred at approximately 16 cal. ka. To further explore the possible climatic relationship of Uinta Mountain glaciers and the lake, and to add to the glacial chronology of the Rocky Mountains, we assembled a range-wide chronology of latest Pleistocene terminal moraines based on seventy-four cosmogenic 10Be surface-exposure ages from seven glacial valleys. New cosmogenic-exposure ages from moraines in three northern and eastern valleys of the Uinta Mountains indicate that glaciers in these parts of the range began retreating at 22–20 ka, whereas previously reported cosmogenic-exposure ages from four southern and western valleys indicate that ice retreat began there between 18 and 16.5 ka. This spatial asynchrony in the start of the last deglaciation was accompanied by a 400-m east-to-west decline in glacier equilibrium-line altitudes across the Uinta Mountains. When considered together, these two lines of evidence support the hypothesis that Lake Bonneville influenced the mass balance of glaciers in southern and western valleys of the range, but had a lesser impact on glaciers located farther east. Regional-scale variability in the timing of latest Pleistocene deglaciation in the Rocky Mountains may also reflect changing precipitation patterns, thereby highlighting the importance of precipitation controls on the mass balance of Pleistocene mountain glaciers.  相似文献   

10.
Our knowledge about the glaciation history in the Russian Arctic has to a large extent been based on geomorphological mapping supplemented by studies of short stratigraphical sequences found in exposed sections. Here we present new geochronological data from the Polar Ural Mountains along with a high‐resolution sediment record from Bolshoye Shchuchye, the largest and deepest lake in the mountain range. Seismic profiles show that the lake contains a 160‐m‐thick sequence of unconsolidated lacustrine sediments. A well‐dated 24‐m‐long core from the southern end of the lake spans the last 24 cal. ka. From downward extrapolation of sedimentation rates we estimate that sedimentation started about 50–60 ka ago, most likely just after a large glacier had eroded older sediments from the basin. Terrestrial cosmogenic nuclide (TCN) exposure dating (10Be) of boulders and Optically Stimulated Luminescence (OSL) dating of sediments indicate that this part of the Ural Mountains was last covered by a coherent ice‐field complex during Marine Isotope Stage (MIS) 4. A regrowth of the glaciers took place during a late stage of MIS 3, but the central valleys remained ice free until the present. The presence of small‐ and medium‐sized glaciers during MIS 2 is reflected by a sequence of glacial varves and a high sedimentation rate in the lake basin and likewise from 10Be dating of glacial boulders. The maximum extent of the mountain glaciers during MIS 2 was attained prior to 24 cal. ka BP. Some small present‐day glaciers, which are now disappearing completely due to climate warming, were only slightly larger during the Last Glacial Maximum (LGM) as compared to AD 1953. A marked decrease in sedimentation rate around 18–17 cal. ka BP indicates that the glaciers then became smaller and probably disappeared altogether around 15–14 cal. ka BP.  相似文献   

11.
Isla de los Estados is a mountainous island southeast of Tierra del Fuego, in southernmost South America. Its central and eastern parts have an alpine topography, transected by U-shaped valleys, small, partly over-deepened fjords, and a multitude of abandoned cirques, all associated with extensive former local glaciations. Traces of glacial erosion generally reach 400–450 m a.s.l., and above that trimline a distinct sharp-edged nunatak derived landscape is present. The westernmost part of the island has a lower, more subdued topography, reflecting its “softer” geology but possibly also over-running and erosion by mainland-derived ice streams. The present study concentrated on glacigenic sediment sequences exposed along coastal erosional cliffs. A combination of OSL and 14C datings show that these sediments mostly date from the latest (Wisconsinan/Weichselian) glacial cycle, i.e. from the last ca. 100 ka with the oldest (glaciolacustrine) deposits possibly as old as 90–80 ka. The upper parts of overlying tills, with associated lateral and terminal moraines from glaciers that expanded onto an eustatically exposed dry shelf north of the island, date from the last global glacial maximum (LGM). Radiocarbon ages of peat and lake sediments indicate that deglaciation began 17–16 cal ka BP.  相似文献   

12.
The Late Weichselian ice sheet of western Svalbard was characterized by ice streams and inter‐ice‐stream areas. To reconstruct its geometry and dynamics we investigated the glacial geology of two areas on the island of Prins Karls Forland and the Mitrahalvøya peninsula. Cosmogenic 10Be surface exposure dating of glacial erratics and bedrock was used to constrain past ice thickness, providing minimum estimates in both areas. Contrary to previous studies, we found that Prins Karls Forland experienced a westward ice flux from Spitsbergen. Ice thickness reached >470 m a.s.l., and warm‐based conditions occurred periodically. Local deglaciation took place between 16 and 13 ka. At Mitrahalvøya, glacier ice draining the Krossfjorden basin reached >300 m a.s.l., and local deglaciation occurred at c. 13 ka. We propose the following succession of events for the last deglaciation. After the maximum glacier extent, ice streams in the cross‐shelf troughs and fjords retreated, tributary ice streams formed in Forlandsundet and Krossfjorden, and, finally, local ice caps were isolated over both Prins Karls Forland and Mitrahalvøya and their adjacent shelves.  相似文献   

13.
Recent research based primarily on exposure ages of boulders on moraines has suggested that extensive ice masses persisted in fjords and across low ground in north‐west Scotland throughout the Lateglacial Interstade (≈ Greenland Interstade 1, ca. 14.7–12.9 ka), and that glacier ice was much more extensive in this area during the Older Dryas chronozone (ca. 14.0 ka) than during the Younger Dryas Stade (ca. 12.9–11.7 ka). We have recalibrated the same exposure age data using locally derived 10Be production rates. This increases the original mean ages by 6.5–12%, implying moraine deposition between ca. 14.3 and ca. 15.1 ka, and we infer a most probable age of ca. 14.7 ka based on palaeoclimatic considerations. The internal consistency of the ages implies that the dated moraines represent a single readvance of the ice margin (the Wester Ross Readvance). Pollen–stratigraphic evidence from a Lateglacial site at Loch Droma on the present drainage divide demonstrates deglaciation before ca. 14.0 ka, and therefore implies extensive deglaciation of all low ground and fjords in this area during the first half of the interstade (ca. 14.7–14.0 ka). This inference appears consistent with Lateglacial radiocarbon dates for shells recovered from glacimarine sediments and a dated tephra layer. Our revised chronology conflicts with earlier proposals that substantial dynamic ice caps persisted in Scotland between 14 and 13 ka, that large active glaciers probably survived throughout the Lateglacial Interstade and that ice extent was greater during the Older Dryas period than during the Younger Dryas Stade. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

14.
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15.
Blomvåg, on the western coast of Norway north of Bergen, is a classical site in Norwegian Quaternary science. Foreshore marine sediments, named the Blomvåg Beds and now dated to the Bølling‐Allerød from 14.8 to 13.3 cal. ka BP, contain the richest Lateglacial bone fauna in Norway, numerous mollusc shells, driftwood, and flint that some archaeologists consider as the oldest traces of humans in Norway. The main theme of this paper is that the Blomvåg Beds are overlain by a compact diamicton, named the Ulvøy Diamicton, which was interpreted previously as a basal till deposited during a glacial re‐advance into the ocean during the Older Dryas (c. 14 cal. ka BP). Sediment sections of the Blomvåg Beds and the Ulvøy Diamicton were exposed in ditches in a cemetery that was constructed in 1941–42 and have subsequently not been accessible. A number of radiocarbon and cosmogenic 10Be exposure ages demonstrate that the diamicton is not likely to be a till because minimum deglaciation ages (14.8–14.5 cal. ka BP) from the vicinity pre‐date the Ulvøy Diamicton. We now consider that sea ice and icebergs formed the Ulvøy Diamicton during the Younger Dryas. The Scandinavian Ice Sheet margin was located on the outermost coastal islands between at least c. 18.5 and 14.8 cal. ka BP; however, no ice‐marginal deposits have been found offshore from this long period. The Older Dryas ice margin in this area was located slightly inside the Younger Dryas margin, whereas farther south it was located slightly beyond the Younger Dryas margin.  相似文献   

16.
The influence of the morphological setting on the denudation of carbonate landscapes and the respective contributions of mechanical and chemical weathering processes are still debated. We have addressed these questions by measuring 36Cl concentrations in 40 samples from the Luberon mountain, SE France, to constrain the denudation of various landscape elements. We observe a clear contrast between the local denudation rates from the flat summit surface, clustered around 30 mm/ka, and the basin‐average denudation rates across the flanks, ranging from 100 to 200 mm/ka. This difference highlights the transient evolution of the range, whose topography is still adjusting to previous uplift events. Such a pattern also suggests that carbonate dissolution is not the only driver of denudation in this setting, which appears to be significantly controlled by slope‐dependent processes.  相似文献   

17.
The interplay between the onshore and offshore areas during the Last Glacial Maximum and the deglaciation of the Scandinavian Ice Sheet is poorly known. In this paper we present new results on the glacial morphology, stratigraphy and chronology of Andøya, and the glacial morphology of the nearby continental shelf off Lofoten–Vesterålen. The results were used to develop a new model for the timing and extent of the Scandinavian Ice Sheet in the study area during the local last glacial maximum (LLGM) (26 to 16 cal. ka BP). We subdivided the LLGM in this area into five glacial events: before 24, c. 23 to 22.2, 22.2 to c. 18.6, 18 to 17.5, and 16.9–16.3 cal. ka BP. The extent of the Scandinavian Ice Sheet during these various events was reconstructed for the shelf areas off Lofoten, Vesterålen and Troms. Icecaps survived in coastal areas of Vesterålen–Lofoten after the shelf was deglaciated and off Andøya ice flowed landwards from the shelf. During the LLGM the relative sea level was stable until 18.5 cal. ka BP, and thereafter there was a sea‐level drop on Andøya. Thus, relative sea level (i.e. a sea level rise) does not seem to be a driving mechanism for ice‐margin retreat in this area but the fall in sea level may have had some importance for the grounding episodes on the banks during deglaciation. The positions of the grounding zone wedges (GZWs) in the troughs are related to the morphology as they are often located where the troughs narrow.  相似文献   

18.
Recent changes along the margins of the Antarctic Peninsula, such as the collapse of the Wilkins Ice Shelf, have highlighted the effects of climatic warming on the Antarctic Peninsula Ice Sheet (APIS). However, such changes must be viewed in a long-term (millennial-scale) context if we are to understand their significance for future stability of the Antarctic ice sheets. To address this, we present nine new cosmogenic 10Be exposure ages from sites on NW Alexander Island and Rothschild Island (adjacent to the Wilkins Ice Shelf) that provide constraints on the timing of thinning of the Alexander Island ice cap since the last glacial maximum. All but one of the 10Be ages are in the range 10.2–21.7 ka, showing a general trend of progressive ice-sheet thinning since at least 22 ka until 10 ka. The data also provide a minimum estimate (490 m) for ice-cap thickness on NW Alexander Island at the last glacial maximum. Cosmogenic 3He ages from a rare occurrence of mantle xenoliths on Rothschild Island yield variable ages up to 46 ka, probably reflecting exhumation by periglacial processes.  相似文献   

19.
Relict rock glaciers have considerable potential for contributing to palaeoclimatic reconstruction, but this potential is often undermined by lack of dating control and problems of interpretation. Here we reinvestigate and date four proposed ‘rock glaciers’ in the Cairngorm Mountains and show that the morphology of only one of these appears consistent with that of a true rock glacier produced by creep of underlying ice or ice‐rich sediment. All four features comprise rockslide or rock avalanche runout debris, and the possibility that all four represent unmodified runout accumulations cannot be discounted. Surface exposure dating of the four debris accumulations using cosmogenic 10Be produced uncertainty‐weighted mean ages of 15.4 ± 0.8 ka, 16.2 ± 1.0 ka, 12.1 ± 0.6 ka and 12.7 ± 0.8 ka. All four ages imply emplacement under cold stadial conditions, two prior to the Windermere Interstade of ca. 14.5–12.9 cal. ka BP and two during the Loch Lomond Stade of ca. 12.9–11.5 cal. ka BP. The above ages indicate that paraglacial rock‐slope failure on granite rockwalls occurred within a few millennia after deglaciation. The mean exposure ages obtained for runout debris at two sites – Strath Nethy (16.2 ± 1.0 ka) and Lairig Ghru (15.4 ± 0.8 ka) – are consistent with basal radiocarbon ages from Loch Etteridge, 22 km to the southwest (mean = 15.6 ± 0.3 cal. ka BP) and imply widespread deglaciation of the Cairngorms and adjacent valleys before 15 ka and possibly 16 ka. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

20.
The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau(QTP) is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides(TCN) 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap(pDIC), southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B?lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.  相似文献   

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