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1.
Vincent R. Rinterknecht Peter U. Clark Grant M. Raisbeck Franoise Yiou Edward J. Brook Silvio Tschudi Juha P. Lunkka 《Quaternary Science Reviews》2004,23(23-24):2283-2289
We determined in situ cosmogenic 10Be ages for nine boulders sampled on the Salpausselkä I (Ss I) Moraine. Previous dating of this moraine indicated that it formed during the Younger Dryas Stadial along the southern margin of the Scandinavian Ice Sheet in southern Finland. Our new exposure ages range from 10.9±1.0 to 13.5±1.2 10Be ka, with an error-weighted mean age of 12.4±0.7 10Be ka. Our results confirm four previous 10Be ages obtained 40 km northeast of our sample location. The combined data (n=13) indicate that retreat from the Ss I Moraine occurred at 12.5±0.7 10Be ka, in excellent agreement with an age of 12.1 ka for retreat from the Ss I Moraine based on varve chronologies. These results identify the Ss I Moraine as among the best-dated margins associated with Late Quaternary ice sheets. 相似文献
2.
The chronostratigraphy of the latest Middle Pleistocene aeolian and alluvial activity on the Island of Hvar,eastern Adriatic,Croatia 
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下载免费PDF全文 Lara Wacha Igor Vlahović Sumiko Tsukamoto Marijan Kovačić Ozren Hasan Davor Pavelić 《Boreas: An International Journal of Quaternary Research》2016,45(1):152-164
Pleistocene aeolian sands and alluvial deposits can frequently be traced along the Mediterranean coast. Such deposits also exist along the eastern Adriatic coast and the nearby islands. Four stratigraphical sections of these deposits were studied on the Island of Hvar with the purpose of establishing a chronological framework of the aeolian–alluvial depositional system, using luminescence dating and magnetic susceptibility stratigraphy. Luminescence dating was applied on coarse‐grained feldspar and quartz grains separated from the sands. Both quartz optically stimulated luminescence (OSL) and feldspar post‐IR infrared stimulated luminescence (pIRIR) age estimates are in good agreement, with values ranging between 167±24 to 120±12 ka (OSL) and 179±18 to 131±18 ka (pIRIR measured at 290 °C) after a fading correction for the pIRIR signal. The results can be clearly correlated to around the end of oxygen isotope stage (OIS) 6 and the beginning of OSI 5, indicating that the aeolian accumulation of sands was a result of the Penultimate Glacial and climate fluctuations at the beginning of the Last Interglacial. Variations in magnetic susceptibility (MS) data can be interpreted alongside these dating results; several stronger peaks detected at the very end of the Penultimate Glacial and the initial stage of the Last Interglacial cycle most probably indicates more intensive pedogenesis resulting from a more favourable climate, probably because of climate changes. Breccias related to major bounding surfaces in association with evidence of soil formation and bioturbation could be the result of more favourable climate conditions and changes during the transition from OIS 6 to OIS 5 (Penultimate Glacial–Last Interglacial). These results are in agreement with similar data from the wider Mediterranean area. 相似文献
3.
A new feldspar relative TL dating method is proposed that enables dating of pre-Weichselian loess older than 130 ka, by applying the additive γ dose technique and the Mejdahl's exponential extrapolation to alkali feldspar coarse grains. The method is applied to loess deposits from various reference loessic sections of NW Europe. Our relative TL age estimates are consistent with the information provided by the regional stratigraphy; furthermore, they lead to a clear separation of the pre-Weichselian periods of loess deposition in the time period 130 ka–300 ka. 相似文献
4.
A. Kar A. K. Singhvi S. N. Rajaguru N. Juyal J. V. Thomas D. Banerjee R. P. Dhir 《第四纪科学杂志》2001,16(1):61-68
Geomorphological processes in the Thar Desert of India are largely climate driven. In the lower reaches of the River Luni (the only major drainage system in the Thar Desert) a fluvio‐aeolian sequence was located at a site called Khudala. Sediments of this sequence represented a variety of depositional environments, namely aeolian, fluvially reworked aeolian, overbank deposits, gravels, and occasional evidence of pedogenesis. This provided a good opportunity to study aeolian–fluvial interaction in the region and for deducing climatic records. From the luminescence dating standpoint these sequences offered a good opportunity for a comparative study of thermoluminescence (TL), blue‐green light stimulated luminescence (BGSL) and infrared light stimulated luminescence (IRSL) on different mineral separates of identical provenance but deposited under different environments. Broadly, within experimental errors, the TL ages agreed with BGSL and IRSL ages on aeolian sands, but differed substantially in the case of fluvially reworked and proximally deposited sands and silts. The sequence provided a record spanning more than 100 ka, with an aeolian phase at > 100 ka, a channel activation phase between 70 and 30 ka and a phase of climate instability between 13 and 8 ka. This appears consistent with the records of monsoon performance during this period, which includes the Younger Dryas. It is also inferred that during the Last Glacial epoch, geomorphological processes in the Thar (both aeolian and fluvial) were dormant largely on account of their relationship with the southwest monsoon. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
5.
B.W. Smith 《Quaternary Science Reviews》1988,7(3-4)
Auto-regenerative dating of zircon grains from fired materials has been shown to be a very powerful technique. The high internal dose rate in zircon gives a measurable auto-regenerated TL signal a few months after the natural TL measurement, allowing the determination of age without dosimetry. The technique has been extended to zircon grains from sediments, using optically stimulated luminescence (OSL) techniques to measure the natural signal. The auto-regenerated signal is only a few hundred photons and cannot be measured above background using present OSL techniques, so it is counted using the highly sensitive TL reader developed for fired zircon grains. Preliminary measurements on fired zircons are in good accord with TL dating and the known ages, but precision becomes poor for samples <1 ka in age. Possible improvements using auto-regenerative phototransfer TL dating are discussed. 相似文献
6.
JAN‐PIETER BUYLAERT SÉBASTIEN HUOT ANDREW S. MURRAY PETER VAN DEN HAUTE 《Boreas: An International Journal of Quaternary Research》2011,40(1):46-56
Buylaert, J.‐P., Huot, S., Murray, A.S. & Van den haute, P.: Infrared stimulated luminescence dating of an Eemian (MIS 5e) site in Denmark using K‐feldspar. Boreas, 10.1111/j.1502‐3885.2010.00156.x. ISSN 0300‐9483. Infrared stimulated luminescence (IRSL) dating of K‐feldspars may be an alternative to quartz optically stimulated luminescence (OSL) dating when the quartz OSL signal is too close to saturation or when the quartz luminescence characteristics are unsuitable. In this paper, Eemian (MIS 5e) coastal marine sands exposed in a cliff section on the coast of southern Jutland (Denmark) are used to test the accuracy and precision of IRSL dating using K‐feldspars. This material has been used previously to test quartz OSL dating ( Murray & Funder 2003 ): a small systematic underestimation of <10% compared to the expected age of ～130 ka was reported. In our study, a single‐aliquot regenerative‐dose (SAR) IRSL protocol is used to determine values of equivalent dose (De) and the corresponding fading rates (g values). A significant age underestimation (of up to ～35%) is observed; this is attributed to anomalous fading. Using a single site‐average fading rate of 3.66 ± 0.09%/decade to correct the IRSL ages for all samples provides good agreement between the average fading‐corrected K‐feldspar age (119 ± 6 ka) and the independent age control (132–125 ka). This is despite the reservations of Huntley & Lamothe (2001) that their fading correction method is not expected to work on samples older than ～20–50 ka. This fading‐corrected feldspar result is not significantly different from the overall revised quartz age (114 ± 7 ka) also presented here. We conclude that fading‐corrected IRSL ages measured using K‐feldspar may be both precise and accurate over a greater age range than might be otherwise expected. 相似文献
7.
Continuing developmental work into optical dating has led to some clarification of the optical behaviour of quartz and feldspar sediment extracts. We have verified the key assumption intrinsic to the method — that the optical signal is zeroed completely upon exposure to daylight. We also show that the rate of zeroing in optical dating is much more rapid than it is in TL dating.Studies concerned with the extraction of the thermally stable signal from laboratory-irradiated samples showed that problems may arise from medium-to-high-temperature preheating of young samples. Optical alternatives to thermal stabilization were tested using dye and krypton lasers. Using a krypton laser we have succeeded in obtaining an equivalent dose of 0.0 ± 0.7 Gy for the quartz from a modern intertidal sand, and an average dose of 120 ± 22 Gy for the feldspar extract of a 70 ka sand unit. Both were obtained using six wavelengths, from the infrared to the violet, and no dependence on wavelength was found. We found that the photon energies of infrared and deep red light can stimulate luminescence in unirradiated quartz and feldspar extracts of sediments. This was not expected, and suggests that the process of trap emptying is more complex than we had envisioned, but implies a far greater than expected degree of technical flexibility for the optical dating method. 相似文献
8.
Dam Quang-Minh Manfred Frechen Tran Nghi Jan Harff 《International Journal of Earth Sciences》2010,99(8):1731-1740
In Vietnam, the coastal sand barriers and dunes located in front of the steep slopes of the high rising Truong Son Mountains
are sensitive to climate and environment change and give evidence for Holocene sea-level rise. The outer barrier sands were
deposited shortly before or contemporaneous with the local sea-level high stand along the Van Phong Bay postdating the last
glacial maximum (LGM). Optically stimulated luminescence (OSL) dating yielded deposition ages ranging from 8.3 ± 0.6 to 6.2 ± 0.3 ka
for the stratigraphically oldest exposed barrier sands. Further periods of sand accumulation took place between 2.7 and 2.5 ka
and between 0.7 and 0.5 ka. The youngest period of sand mobilisation was dated to 0.2 ± 0.01 ka and is most likely related
to reworked sand from mining activities. At the Suoi Tien section in southern central Vietnam, the deposition of the inner
barrier sands very likely correlate with an earlier sea-level high stand prior to the last glaciation. OSL age estimates range
from 276 ± 17 to 139 ± 15 ka. OSL dating significantly improves our knowledge about the sedimentary dynamics along the coast
of Vietnam during the Holocene. 相似文献
9.
Huang Pei-Hua Jin Si-Zhao Peng Zhi-Cheng Liang Ren-Yu Quan Yu-cai Wang Zhao-Rong 《Quaternary Science Reviews》1988,7(3-4)
This paper reports the preliminary application of ESR dating to loess strata. The samples were collected from the 7th palaeosol layer (S7) of the Luochuan section, Shaanxi province in China. The ESR age of S7 is 736 ka (total dose 2945 Gy, annual dose 4 mGy/year). This age represents the original eolian accumulation age. The result is consistent with the palaeomagnetic data (730 ka). We have also carried out thermal annealing experiments on quartz grains from the S7 sample. ESR intensities (g = 2.0005) increase from 25°C to 320°C. It may be that trapped electrons transfer into the E′ centre site. ESR intensities decrease from 340°C to 460°C due to thermal annealing. We obtained a mean-life of E′ centre electrons at 20°C of 6.66 × 108 years. The activation energy is 1.35 eV and frequency factor is 3.7 × 108 min−1. 相似文献
10.
天山乌鲁木齐河源末次冰期冰川沉积光释光测年 总被引：6，自引：5，他引：1
乌鲁木齐河源地区是中国冰川遗迹保存最丰富、地貌最典型的区域之一,是根据冰川遗迹重建第四纪冰川历史的理想地区。大量的研究工作以及技术测年结果也使其成为试验冰川沉积光释光（optically stimulated luminescence,OSL）测年可行性的理想地点。共采集了6个冰碛及上覆黄土样品用于光释光测年。提取38~63 μm的石英颗粒,运用SAR-SGC法测试等效剂量。各种检验表明测试程序是适用的。通过地貌地层关系、重复样品、已有年代的对比等方法,检验该地冰川沉积OSL测年的可行性。结果表明,OSL年代结果与地貌地层新老关系非常吻合,与已有的其他测年技术的年代结果也具可比性,表明这些样品的OSL信号在沉积之前晒退较好,OSL年代是可信的。冰川观测站侧碛垄的OSL年代为14.8±1.2 ka;9号冰川支谷口附近冰碛的OSL年代为13.5±1.1 ka和17.2±1.3 ka;上望峰冰碛的OSL年代为20.1±1.6 ka。综合OSL年代结果与此前其他测年结果,这几套冰碛垄形成于深海氧同位素MIS 2阶段应该是比较统一的认识。上望峰冰碛上覆黄土的OSL年代（10.5±0.8 ka）也印证了该结论。OSL年代指示上望峰冰碛对应于末次冰期最盛期,冰川观测站和9号冰川支谷谷口冰碛对应于晚冰期。下望峰冰碛的OSL年代为36.3±2.8 ka,对应于MIS 3阶段。下望峰冰碛的形成时代,仍有待更多沉积学以及测年工作进一步确定。 相似文献
11.
Livio Sirovich 《第四纪科学杂志》1998,13(1):65-71
This paper assesses the age of the Tagliamento Morainic Amphitheatre (northeast Italy), one of the largest morainic bodies in the piedmont area of northern Italy, using new stratigraphical and thermoluminescence (TL) data obtained from a site located on the inner flank of the amphitheatre. Two samples from a 12-m-thick stratum of fluviolacustrine, non-varved, fine sand provided TL ages of approximately 110 ± 16 ka BP. This sandy layer lies below a 6-m-thick, massive (non-laminated), clayey stratum. It is hypothesised that a large but short-lived lake formed during the interglacial phase separating the penultimate and last glaciations. Assigning a ‘Riss’ age to the southeastern part of the amphitheatre therefore regains credence. © 1998 John Wiley & Sons, Ltd. 相似文献
12.
火山灰年代学是判断第四纪沉积物年龄的有效手段。文章报告在江苏三处旧石器遗址（和尚墩、放牛山和将军崖）上部堆积中发现的火山玻璃及初步研究结果。和尚墩遗址的火山玻璃主要出现在两个层位: 上层距地表约45cm,火山玻璃的水合层很薄,年代有可能晚于K Ah火山（7.3ka）; 下层距地表约70cm,火山玻璃的水合过程已经完成,时代稍老,大致与日本晚更新世火山同期,至少相当于AT火山,年代等于/大于25ka。遗址中的火山玻璃分为pm型和bw型。形态、屈折率及微量包含物的研究表明,火山玻璃的来源可能与日本的火山喷发无关。江苏旧石器遗址中发现的火山玻璃对判断中国东部地区更新世沉积物时代以及埋藏其中的旧石器遗存年代具标志意义。 相似文献
13.
Hema Achyuthan Nagalakshmi Thirunavukarasu 《Journal of the Geological Society of India》2009,73(5):683-696
In this paper we present Quaternary stratigraphy of the area around Chennai based on archaeological findings on the ferricrete
surface, geomorphological observations supplemented by radiocarbon dating. The coastal landscape around Chennai, Tamil Nadu,
has preserved ferruginised boulder gravel deposits, ferricretes and fluvial deposits of varying thickness. The area studied
is approximately 150 km east to west and 180 km north to south with a broad continental shelf towards the seaward. Several
rivers enter the Bay of Bengal along its shores like the Koratallaiyar, Cooum and the Adyar. Precambrian charnockite and Upper
Gondwana sandstone and shale bedrock rim the shelf margin. For the most part, the Upper Pleistocene-Holocene fluvial sediments
overlie an erosion surface that has cut into older Pleistocene sediments and ferricrete surface. Incised valleys that cut
into this erosion surface are up to 5–6 km wide and have a relief of at least 30 m. The largest valley is that cut by the
Koratallaiyar River. Holocene sediments deposited in the incised valleys include fluvial gravels, early transgressive channel
sands and floodplain silts. Older Pleistocene sediments are deposited before and during the 120-ka high stand (Marine isotope
stage 5). They consist of ferricretes and ferricrete gravel formed in nearshore humid environments. Muddy and sandy clastic
sediments dated to the ca. 5 ka highstand suggest that the climate was semi arid at this time with less fluvial transport.
The coarsening up sequence indicates deposition by high intensity channel processes. Pedogenic mottled, clayey silt unit represents
an important tectonic event when the channel was temporarily drained and sediment were sub aerially exposed. Uplift of the
region has caused the local rivers to incise into the landscape, forming degradation terraces. 相似文献
14.
《Quaternary Science Reviews》2003,22(10-13):1067-1076
This study is concerned with the Late Quaternary climatic chronology of the Strzelecki Desert dunefields in central Australia. The sand ridges comprise layers of quartz sand, some of which include palaeosol horizons with carbonated rootlets providing excellent opportunity for dating of alternations of dune building and stability by using optically stimulated luminescence (OSL). Deduced from the OSL age of the oldest aeolian layer dated, we conclude that the onset of aridity dates back to at least ∼65 ka. Older phases of aeolian activity though, following a fluvial depositional phase 160 ka ago, cannot be excluded, although no aeolian layers giving evidence for this have been found in the two dunes dated here. Unconsolidated dune sands in the upper part of one section with Late Holocene (4 ka to modern) depositional ages indicate a reactivation of the dunefield in recent times.From the crosscheck of 14C ages of the carbonated rootlets with OSL results it is concluded that under the given environmental conditions radiocarbon dating of the calcareous rootlets is not able to provide reliable ages for the phase of soil development. 相似文献
15.
In Ostrobothnia, western Finland, buried fossil soils have been recognised in a number of places in the sandy sediments that occur between glaciofluvial deposits and overlying till. Samples from the soil horizons as well as below and above them were taken for optically stimulated luminescence (OSL) dating. The same sites were also sampled for thermoluminescence (TL) dating. Altogether five TL dates and seventeen OSL dates were obtained. The OSL dates can be grouped into two age classes, (i) 120-163 ka and (ii) 76-106 ka, whereas all TL dates are of the order 135-155 ka. A comparison between the results obtained from the two dating methods shows that OSL dates are generally younger than the TL dates for the same sample. The discrepancy may arise partly from problems of setting a correct residual level in TL dating. If this is the case then the TL dates may indicate an upper limit for the true age. The results support the geological interpretation that the fossil soils were formed during the last interglacial, that the soil-forming processes possibly also continued during the first Early Weichselian stadial and interstadial (Brørup sensu lato), and that in general the till-covered glaciofluvial sequences, interpreted as eskers in Ostrobothnia, were deposited during the Saalian or Early Weichselian deglaciation. 相似文献
16.
Electron microprobe dating of monazite substantiates ages of major geological events in the southern Brazilian shield 总被引：1，自引：0，他引：1
Hugo Tickyj Lo A. Hartmann Marcos A. Z. Vasconcellos Ruy P. Philipp Marcus V. D. Remus 《Journal of South American Earth Sciences》2004,16(8):84
To obtain the chemical Th*–Pb isochron ages and surface maps of monazite crystals in igneous and metamorphic rocks from the southern Brazilian Shield, we employ Th–U-total Pb dating by an electron probe microanalyzer. The ages of two Trans-Amazonian metamorphic events are given by a felsic, garnet-bearing granulite from the Santa Maria Chico granulitic complex. The age of the first event, at approximately 2.35 Ga, was obtained by surface mapping in a grain included in garnet. The dating of the second event, 1899±43 Ma, is in agreement with previous data obtained in zircon crystals with sensitive high-resolution ion microprobe. Other determinations belong to the Brasiliano cycle. In the São Gabriel block, an age of 643±129 Ma was obtained on monazite from a staurolite-garnet schist of the Cambaizinho Formation, whereas a staurolite-bearing schist from the Passo Feio complex yielded a 510±68 Ma age. Several units in the Dom Feliciano belt were dated, including the biotite-sillimanite gneisses of the Várzea do Capivarita complex (552±90 Ma), the sillimanite-garnet gneisses of Camboriú complex (565±77 Ma), the Três Figueiras granite (558±57 Ma), and the Plaza Itapema granite (545±55 Ma). The ages presented in this study, obtained through monazite chemical dating, are confirmed through comparison with previous data regarding zircon crystals from the same geological units. 相似文献
17.
Thermoluminescence dating of potassium feldspar coarse grains from the fossiliferous Holsteinian marine formation of Herzeele, at the southern limit of the North Sea Basin, yields a minimum age of 228 £ 30 ka. A tentative correction for the long-term fading of the TL signal in potassium feldspar is proposed, assuming a lifetime (τ) of 711 ka. This correction would yield a preliminary age estimate of 271 £ 36 ka. These results support a minimum Oxygen Isotope Stage 7 age, but do not preclude, at this stage of our research, a possible correlation with late Oxygen Isotope Stage 9. These results are in agreement, within the error of the method, with independent absolute dates (U-Th and ESR) obtained on in situ marine shells, which range from 225 ka to 348 ka. This study provides evidence of the reliability of TL age estimates on potassium feldspar coarse grains from shallow-marine sediments older than the Last Interglacial. 相似文献
18.
The caves near Naracoorte, South Australia, contain one of the richest and most diverse fossil faunal assemblages on the Australian continent. Three sites were selected for electron spin resonance (ESR) dating because clastic, fossiliferous sediments were sandwiched between speleothem layers. This allows independent age control by highly precise thermal ionization mass‐spectrometry (TIMS) U‐series dating. We find that all ESR results agree within the constraints given by the U‐series dates, and allow further refinement of the age of the fauna analysed, indicating that most of the fauna in the large Victoria Cave Fossil Chamber is twice as old as reported previously. Our dating results, spanning from 280 to 500 ka for the Fossil Chamber, Victoria Cave, to about 125 ka for the Grant Hall, Victoria Cave, and 170 to 280 ka for the Fossil Chamber, Cathedral Cave, indicate little change, if any, in the megafaunal assemblage from the early Middle to the early Late Pleistocene. This changed dramatically after the last interglacial, when a large proportion of the megafauna suddenly disappeared. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
19.
SHRIMP U–Pb zircon dating of gabbro, anorthosite, trondhjemite and granodiorite from the Jinshajiang ophiolitic mélange of southwestern China provides geochronological constraints on the evolution of Paleo-Tethys. The ophiolitic mélange is exposed for about 130 km along the Jinshajiang River where numerous blocks of serpentinite, ultramafic cumulate, gabbro, sheeted dikes, pillow lavas and radiolarian chert are set in a greenschist matrix. A cumulate gabbro-anorthosite association and an amphibole gabbro have ages of 338 ± 6 Ma, 329 ± 7 Ma and 320 ± 10 Ma, respectively, which constrain the time of formation of oceanic crust. An ophiolitic isotropic gabbro dated at 282–285 Ma has the same age as a trondhjemite vein (285 ± 6 Ma) cutting the gabbro. These ages probably reflect a late phase of sea-floor spreading above an intra-oceanic subduction zone. At the southern end of the Jinshajiang belt, a granitoid batholith (268 ± 6 Ma), a gabbro massif (264 ± 4 Ma), and a granodiorite (adakite) intrusion (263 ± 6 Ma) in the ophiolitic mélange constitute a Permian intra-oceanic plutonic arc complex. A trondhjemite dike intruded serpentinite in the mélange at 238 ± 10 Ma and postdates the arc evolution of the Jinshajiang segment of Paleo-Tethys. 相似文献