Optical Dating Of Sediments Research Articles

Hominin occupation of the Tibetan Plateau during the Last Interglacial Complex

The Paleolithic archaeological record of the Tibetan Plateau is crucial for understanding human ecological and genetic adaptation to life in high altitudes. Recent work on the Tibetan Plateau has documented hominin occupations by Denisovans at Baishiya Karst Cave (BKC) from at least ca. 160, and again around 100 and 60 thousand years ago (ka), followed by modern human occupation at Nwya Devu (ND) around 30–40 ka. However, with the exception of these two geographically distinct sites, there are very few Paleolithic sites with secure stratigraphy and reliable dates on the Tibetan Plateau. Thus, the spatial and temporal history of Paleolithic hominin occupation of the Tibetan Plateau remains poorly understood. Here we report a newly discovered well-stratified and well-dated Paleolithic site, Jiangjunfu 01 (JJF01), from the northeastern margin of the plateau. Optical dating of sediments from cultural layers shows that the site was occupied by hominin who employed simple core-and-flake technology, during warmer interglacial environments ∼90–120 ka. To date, JJF01 is one of the three oldest archaeological sites with secure stratigraphy and reliable dating from the Tibetan Plateau, further confirming that hominins, potentially Denisovans, occupied and inhabited the highest region of our planet at least by the early Upper Pleistocene.

Optical dating of sediments from manas lake in northwestern china: Paleoenvironmental and neotectonic implications

Manas Lake is a closed lake basin in northern Xinjiang Province of China, with its current lake bed at 244 m a.s.l. Sediments from the lake area provide valuable information about the paleoenvironmental changes in the Westerlies-dominated arid region. To obtain a chronological constraint on the past changes, optically stimulated luminescence dating was conducted on sediments from the lake beaches. The results show that lacustrine episodes dated at ~80–73 ka ago were recorded in northwestern side of the lake at 270 m a.s.l., while paleoshoreline to near-shore environments during ~80–90 ka ago were recorded in the opposite side of the lake at 262 m a.s.l. The ~80 ka old sedimentary layers are overlain by paleoshoreline sediments formed within the last ~1 ka, separated by a large age gap. From this study and the results from previous studies, it is concluded that breaks in sedimentary records are common in the lake area at elevation > 260 m a.s.l. When comparing sedimentary environments at different times from different sites in this study and previous studies, it is suggested that a small amount of uplift of the northwestern side of Manas Lake relative to the southeastern side may have occurred in the last 80 ka.

Optical dating of sediments in Wadi Sabra (SW Jordan)

At Wadi Sabra (SW Jordan) human occupation dates back to the Palaeolithic and Epipalaeolithic. Although there is stratigraphic correlation based on archaeological finds of Ahmarian origin, numerical age estimates are lacking. We applied single-aliquot optical dating of coarse grained quartz of wadi deposits and investigated the luminescence properties in detail to achieve more accurate age information about the time of human occupation. Weak luminescence signals and scattered dose distributions characterise the multi-grain aliquots. The residual doses of the investigated modern wadi sediment are between 0 and 7 Gy. Moreover, comparison of equivalent dose (De) values of 1 mm and 8 mm aliquots shows higher equivalent doses for the large aliquots. Both experiments indicate that the luminescence signal is partially bleached prior to deposition. The dose distributions of all samples are broadly scattered and have overdispersion values between 25 and 43%, some samples are significantly skewed. The shape of the dose distributions points to other sources of scatter, in addition to partial bleaching. Comparison of 1 mm multi-grain and single-grain data demonstrates that the luminescence signal of one multi-grain aliquot most likely is from a single grain. For this reason, variation in the number of photon counts due to the weak luminescence intensity and variations in beta microdosimetry have a bigger impact on the spread of dose distributions. However, we cannot quantify the particular impact of partial bleaching, weak luminescence intensity and beta microdosimetry. To account for the spread of the dose distribution, we use the central age model to calculate equivalent doses. Age calculations yield results in the range of 30–48 ka.

Optical Dating of Sediments in Khari River Basin and Slip Rate Along Katrol Hill Fault (KHF), Kachchh, India

In the central region of Mainland Kachchh, Western India, the Katrol Hill Fault (KHF) is one of the major E-W trending faults. An understanding of the episodes of reactivation during the past has a bearing on the future seismicity in the region. These reactivations are manifested by offset of elevation of fluvial sediments and scarp-derived colluvium in the Khari River basin, SE of Bharasar (23°11'36.5"N, 69°35'22.6"E). Stratigraphic offsets of the sediments at this site suggest three episodes of reactivation of the KHF during the late Quaternary. Optical dating of samples from sediment strata and top layer of scarp-derived colluvium using Natural Sensitivity Corrected - Single Aliquot Regenerative (NCF-SAR) protocol suggested that these events occurred during the past ~30 ka, with the most recent historic episode around 3.0 ka. Given that a part of the slip recorded in the form of sediments offset, was lost due to erosion after faulting, a lower bound to the time averaged slip rate of the segment of KHF, is inferred to be > 0.23 mm/a during the past 30 ka.

Optical dating studies of mud-dominated alluvium and buried hearth-like features from Red River Valley, southern Manitoba, Canada

Optical dating studies of samples of late-Holocene mud-dominated alluvium, and heated alluvium in features interpreted to be hearths, collected from the banks of the Red River, southern Manitoba, Canada, were undertaken to assess the viability of these deposits as chronometers for floodplain evolution. Optical dating was done by utilizing the violet luminescence emitted during infrared excitation of the potassium feldspar in the fine-silt polymineral fraction. The alluvial samples, dated by radiocarbon to be about 1 ka old, yielded maximum limiting optical ages between about 1 and 5 ka, indicating that optical dating of such samples may provide useful chronological information in cases where material suitable for radiocarbon dating is lacking, or in cases where a radiocarbon chronology needs support. Furthermore, the surprisingly low residual optical ages from sediments of this type indicate that there is a high proability that sediments representing similar mud-dominated alluvial environments in the Pleistocene record will yield ages with adequate precision and accuracy. Bulk sediment extracted from the centre of a buried hearth yielded an optical age (1.4 ± 0.2 ka) that was broadly consistent with its associated calibrated radiocarbon age (0.23-1.05 ka), but good agreement (0.79 ± 0.09 ka) was achieved when small fragments of hard-baked mud (ñ0.5 g) extracted from within the feature were optically dated separately; hard-baked fragments from two other hearths yielded similar results. Optical dating of sediments from hearths formed in mud-dominated alluvial sediments thus represents a viable method for obtaining a useful chronology in circumstances where organic material suitable for radiocarbon dating is absent.

Optical dating of sediments associated with a fossil moa skeleton near Tauweru, Wairarapa, New Zealand

Optical dating was undertaken on the finegrained (4–11 μm diam.) fraction of potassium feldspars extracted from sediments associated with a nearly complete fossil moa skeleton uncovered near Tauweru. The optical ages show that the deposit in which the fossil occurred is younger than c. 45 ka, and no older than 18–22 ka. This result is broadly consistent with the calibrated radiocarbon age estimate for the fossil of 16–22 ka, and suggests that the skeleton is of Ohakean age.

Determining the burial time of single grains of quartz using optically stimulated luminescence

In the optical dating of sediments it is usually assumed that the optically stimulated luminescence (OSL) signal has been completely reset by light exposure prior to burial; this assumption is often not valid. One approach to testing, and perhaps circumventing, this assumption is to examine the apparent date of last exposure to daylight of individual sediment grains. This paper reports on the application, for the first time, of 2 new measurement protocols to the estimation of the radiation dose received during burial for individual quartz grains from an aeolian deposit of known age (10,000 year old), which is considered likely to have been completely reset by sunlight at deposition. Additive-dose (laboratory doses added to the burial dose before OSL measurement) and regenerative-dose (doses added after measurement of OSL from burial dose) single-aliquot protocols are applied to 28 and 25 individual grains, respectively; each grain provides an independent estimate (D e) of the burial dose. The average D e from the additive-dose protocol (21.8±1.1 Gy) is in good agreement with the average from the regenerative-dose protocol (23.8±1.0 Gy). Both agree well with: (1) 13 multiple-grain regenerative-dose single-aliquot measurements, each on 1 mg sub-samples, of 23.9±0.3 Gy; (2) 9 multiple-grain additive-dose single-aliquot measurements, also on 1 mg sub-samples, of 22.4±0.7 Gy; and (3) one previously published multiple-aliquot additive-dose estimate of 23.5±0.6 Gy using 52 sub-samples, each of 5 mg. The resulting optical ages are in good accord with 14C and thermoluminescence age determinations. The distribution of equivalent doses in the single grains is, however, unexpectedly large ( σ≈23% of mean D e), given the very likely complete resetting of the OSL signal at deposition. Possible reasons are discussed, and it is concluded that heterogeneity in beta dosimetry is the most likely explanation. The single-grain optical dating protocols reported here allow a detailed examination of the dose distribution in very small samples. Thus, they should enable accurate dates to be obtained for sediments and soils that contain poorly bleached or mixed-age components, as well as deposits in which quartz grains are present in extremely low abundance.

Thermoluminescence dating of St. Croix ceramics: Chronology building in Southwestern Nova Scotia

Using the classic thermoluminescence (TL) dating technique for fired ceramic materials, we have obtained the first direct ages for five ceramic artifacts recovered from BfDa-1, a prehistoric archaeological site located in St. Croix, southcentral Nova Scotia. BfDa-1 is the only archaeological site in Nova Scotia to produce the full range of ceramic styles associated with the Woodland or Ceramic Period (c. 1050 B.C. to A.D. 1500); thus our new chronology can be used to revise the current local and regional ceramic chronologies. The five sherds from the St. Croix site yielded absolute gas of 1.15 ± 0.15 ka to 2.62 ± 0.29 ka (1 ka = 1000 years). The oldest of these TL ages was obtained on a sherd decorated with a pseudoscallop shell design and is in excellent agreement with a 14C date of 2500 ± 120 B.P. associated with Early Ceramic artifacts at this site. The other TL ages are in agreement with the relative ceramic chronology deduced from their decorative attributes. All five TL dates are in the correct depth-age order. This demonstrates that the recent excavations explored a part of the site which remained undisturbed in spite of extensive agricultural and horticultural activities in the vicinity in recent centuries. The dates also indicate a high degree of compression for the cultural remains at the site. They suggest a sediment deposition rate of 1.3 cm/100 yr during the early stages of the occupation period (2000–2600 yr B.P.), and a decrease in the deposition rate to 0.5 cm/100 yr during the last 2000 years. These dates provide the first successful application of TL dating to ceramics of the Minas Basin area. They confirm an initial hypothesis based on the stylistic attributes of ceramics recovered from BfDa-1, that human occupation at the site must have been of long duration. The excellent quality of the analytical data indicates that the TL dating technique should be well suited to the study of ceramic technology in other parts of the province, and that local mineralogy is suitable for optical dating of sediments at the site and elsewhere in Nova Scotia. © 1997 John Wiley & Sons, Inc.

Recent Developments in Optical Dating of Sediments

Abstract Optically stimulated luminescence signals from quartz and feldspars can be used as a tool for dating Quaternary sediments. This paper reviews the studies that have been carried out to understand the basic properties of these minerals and provide a basis for elucidating the mechanisms.

Recent Developments in Optical Dating of Sediments

Optically stimulated luminescence signals from quartz and feldspars can be used as a tool for dating Quaternary sediments. This paper reviews the studies that have been carried out to understand the basic properties of these minerals and provide a basis for elucidating the mechanisms.

The Optical Dating of Sediments Using Quartz

The Optical Dating of Sediments Using Quartz

The Optical Dating of Sediments Using Quartz

Abstract The technique of optical dating has been applied to quartz extracts from geological and archaeological sediments. The method involves measurement of the luminescence emitted when the quartz is optically stimulated, and yields the time which has elapsed since the sediments were last deposited. The luminescence originates from charge in traps associated with the 325 oC TL peak, and the kinetics of charge movement have been carefully considered in the formulation of the dating procedure. A cross-comparison of the optical dates with alternative dating evidence is presented, giving strong indication that the technique is reliable and can be applied to both wind- and water-borne sediments in the age range one thousand to one hundred thousand years. In some circumstances younger dates can be obtained.

Optical dating of sediments

A new method for dating sediments is proposed, which determines the time since the sediment was last exposed to sunlight. An argon-ion laser is used to excite electrons from thermally-stable light-sensitive traps and the subsequent luminescence used as a measure of the past radiation dose. Two sample sequences spanning the periods 0–700 kyr and 0–6 kyr show steadily increasing luminescence with age. An age of 62±8 kyr is obtained for a silt radiocarbon dated at 58.8±0.3 kyr. Problems were found with two much younger samples.