Infrared Optically Stimulated Luminescence Research Articles

Luminescence chronology from the Verkhoyansk Mountains (North-Eastern Siberia)

This study presents new dating results from the Verkhoyansk Mountains in northeastern Siberia. Pleistocene sediments of aeolian and glacial origin have been studied and dated by infrared optically stimulated luminescence (IRSL). The chronostratigraphy of this vast area is mainly based on radiocarbon dating up to now. Aeolian sediments are widespread in the foreland of the Verkhoyansk Mountains. IRSL-dating results indicate two major periods of increased accumulation between 33 and 24 ka and between 13 and 9 ka. A new stratigraphy of Pleistocene glaciations in this area has been developed. Up to five end moraines have been identified in two catchments areas. IRSL was applied to date the sandy and silty sediments covering the glacial deposits in order to get minimum ages. Furthermore, glacial and glacio-fluvial deposits were also sampled from a few locations. According to the IRSL dating results, the uppermost end moraine was deposited prior to 50 ka. The three outermost moraines might have been formed during Early Weicheslian to Saalian times. It is very likely that no major glaciers reached the foreland of the Verkhoyansk Mountains during the Last Glacial Maximum (LGM, MIS 2).

Luminescence chronology of fluvial and aeolian deposits in the Russian Altai (Southern Siberia)

Geomorphological investigations in the Russian Altai Mountains provide evidence for the extent and timing of Late Quaternary glaciations and aeolian sediments. Infrared optically stimulated luminescence (IR-OSL) and thermoluminescence (TL) dating of aeolian sediments from the central part of the Russian Altai were carried out on silty and sandy sediments that cover fluvial and glacio-fluvial terraces. Most samples from loess, loess-like sediments and sandy loess taken from different terrace sequences within the Altai Mountains provide IRSL ages suggesting a main aeolian deposition period between 25 and 15 ka. These data are consistent with those from the adjacent Mongolian Altai. Sand and silt layers within moraines yielded IRSL age estimates between 22 and 19 ka and correlate to the ice margins of the Last Glacial Maximum. Aeolian dune sands overlying or neighbouring the loess-like sediments and the fluvial terraces at some places provide evidence for Late Glacial (around 15 ka) and Early Holocene (around 9 ka) aeolian activity. The youngest sand sheets gave deposition ages of about 1.5 ka. These sediments covered graves and are related to overgrazing. They provide evidence for the significant human impact on the environment. Fluvial sediments, including silt and sandy gravel intermingled with charcoal, yielded contradicting radiocarbon and luminescence ages. IRSL age estimates obtained for the silty layers range from 19 to 18 ka and are significantly older than the radiocarbon ages, which gave sub-recent ages between 1170 and 910 BP. These data indicate fluvial sedimentation of debris and mudflows in a period of deforestation and strong soil erosion related to mining activities during the 9th and 10th century.

Time-resolved luminescence from feldspars: New insight into fading

Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation ( λ = 875 nm ) . We observe that the relative contribution of long lifetime ( ∼ 20 μ s ) components in K-feldspars is greater than that in Na-feldspars at each detection wavelength. From any one feldspar sample, red and blue IR-OSL signals have a greater contribution of long lifetime components than UV IR-OSL. We found this long lifetime component was significantly more stable than shorter lifetime components, by comparing natural/regenerated and prompt/delayed time-resolved IR-OSL. We also compared both pulsed and continuous wave (CW) equivalent dose ( D e ) values from four feldspar samples. For pulsed IR-OSL, the signal was collected between 10 and 100 μ s after the diodes were switched off, to avoid all contributions from short lifetime components. In all cases, the pulsed D e values were larger than the CW D e values, regardless of the type of the feldspar and the detection wavelength; the pulsed D e values were also all consistent with those calculated from the quartz D e . It is possible that the long lifetime component from feldspars do not show anomalous fading.

Paleosols derived from loess and loess-like sediments in the Basin of Persepolis, Southern Iran

In the Basin of Persepolis, late Quaternary basin fills consist of loess, loess-like sediments and fine- or coarse-textured alluvium. The loess and its derivatives are divided by various paleosols, which consist of well-developed fBw(t)-horizons, weakly developed fBwC- and fBwgC-horizons, as well as fAh-horizons. Strongly developed fBtk-horizons occur in stony alluvial fan deposits or superimpose residual loams of carbonate bedrock mixed with loess. The different types of paleosols result from various degrees of soil development as evidenced by micromorphological features such as the birefringence fabrics, and less clearly by pedochemical properties. Based on the stratigraphy and different degrees of soil development, various phases of soil formation and sediment deposition can be distinguished. Infrared optically stimulated luminescence (IRSL), thermoluminescence (TL) and radiocarbon dating methods are consistent with the stratigraphy and yielded, except for one sample, age estimates of less than about 30 ka. The strongly developed fBw(t) and fBtk horizons reflect soil-forming periods prior to the Last Glacial Maximum (LGM) and probably during Marine Isotope Stage 5 (MIS 5), with climatic conditions comparable to the present-day. The upper loess deposits likely formed under considerably cooler and drier climatic conditions during the LGM. However, poor bleaching of sediments prior to final deposition, as indicated by greater TL than IRSL dates, suggest fluvial reworking of these loesses. The weakly developed fAh, fBwC, and fBwgC horizons may indicate interstadial periods of MIS 3 and short phases of climate amelioration during the early Holocene. The formation of the modern soil probably did not start before 7–9 ka.

Luminescence chronology of the Upper Pleistocene loess record at Kurtak in M iddle Siberia

The loess/palaeosol sequence of Kurtak, situated at the western bank of the upper Yenisei in Middle Siberia, represents one of the best developed Middle and Upper Pleistocene sediment records in Yenisei Siberia. More than 40 m thick loess and loess-like sediments intercalated by at least four pedocomplexes are exposed at a steep erosional slope at the bank of the Krasnoyarsk Water Reservoir. Infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) dating techniques have been applied on 38 fine grain samples from the upper 23 m of the profile, representing the penultimate and last interglacial–glacial cycle. The IRSL and TL age estimates are in good agreement with the geological estimates up to the last interglacial soil horizon (oxygen isotope substage (OIS) 5e). The luminescence ages show that the lowermost truncated palaeosol of kastanosjem-type is likely to have formed during the penultimate interglacial upon subaerial deposits. Three weak reddish brown palaeosols intercalated by reworked loess-like sediments correlate with early Upper Pleistocene interstadials (OIS5dion of -a), and a succession of humic horizons alternated by cryoturbation processes (Kurtak pedocomplex) is linked with OIS 3. Thick loess deposits between the pedocomplexes show now significant age increase with depth, indicating high accumulation rates at around 23 ka (OIS 2) and 60 ka (OIS 4).

The coversands and timing of Late Quaternary earthquake events along the Peel Boundary Fault in the Netherlands

AbstractThe coversands along the Peel Boundary Fault in the Netherlands were investigated by a luminescence dating approach combining Infrared Optically Stimulated Luminescence (IRSL) and Thermoluminescence (TL) methods. At the Neer trench, ten samples were collected and investigated in order to set up an independent chronological framework for the deposition history of the fluvio-aeolian and aeolian sediments and hence the timing of Late Weichselian and Holocene earthquake events. Five sedimentary units could be distinguished by this chronological approach. The oldest fluvio-aeolian unit yielded a mean deposition age of 35.9±0.4 ka and is designated to correlate with the Middle Weichselian. An IRSL age estimate of 20.1 ±2.9 ka was determined for the sediment that most likely represents the Older Coversands I, and a mean luminescence age of 15.1±1.2 ka for deposits just below the Beuningen gravel bed. The aeolian sediment from above the Beuningen horizon yielded an IRSL age estimate of 9.4±1.0 ka. The youngest deposits from the colluvial wedge yielded <6.9±0.7 ka BP, and so an earthquake event was likely to occur during the Middle or Late Holocene, as evidenced by the luminescence age estimates.

Testing optically stimulated luminescence dating of sand-sized quartz and feldspar from fluvial deposits

We apply single-aliquot optically stimulated luminescence (OSL) dating to quartz- and feldspar-rich extracts from fluvial channel deposits of the Rhine–Meuse system in The Netherlands. The time of deposition of these deposits is tightly constrained by radiocarbon dating or historical sources. This allows us to compare OSL ages obtained on quartz and infrared OSL (IR-OSL) ages obtained on potassium-rich feldspar with independent ages over the range of 0.3–13 ka. We show that the quartz OSL ages are in good agreement with the expected age. Using IR-OSL dating of feldspar, we find a slight age overestimate for the youngest sample, whereas for older samples the age is significantly underestimated. We also apply OSL dating to older fluvial and estuarine channel deposits with limited independent chronological constraints. Comparison of feldspar IR-OSL ages with the quartz OSL ages up to ∼200 ka shows a clear trend, where the former severely underestimates the latter. This trend is similar to that found for the samples with independent age control, indicating that the feldspar IR-OSL ages are erroneously young for the entire age range. In the youngest samples, incomplete resetting of the IR-OSL signal prior to deposition probably masks the age underestimation. We show that the IR-OSL age underestimation is partly caused by changes in trapping probability due to preheating. Correction for this phenomenon improves the IR-OSL ages slightly, but does not provide a complete solution to the discrepancy. We suggest that, in the light of the problems encountered in the IR-OSL dating of feldspar, quartz is the mineral of choice for OSL dating of these deposits. However, feldspar dating should continue to be investigated, because it has potential application to longer time scales.

The Upper Pleistocene loess record at Harmignies/Belgium — high resolution terrestrial archive of climate forcing

The loess/palaeosol sequence in a section at Harmignies in Belgium is one of the most important Upper Pleistocene sites in Northwest Europe. An extensive luminescence dating study was carried out to get a reliable chronological framework and to understand the climate forcing in an area where continuous permafrost dominated during most of the last glaciations. Twenty-eight samples were investigated by infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) methods resulting in more than 100 luminescence age estimates. The dating results on colluvial sediments are in good agreement with landscape destabilisation phases during OIS 5. During the last glacial, four major periods of loess accumulation were likely to have occurred in Europe. At the Harmignies section, the oldest loess was deposited between 67,000 to 60,000 yr, the second one from 60,000 to 50,000 yr, the third one from 50,000 to 40,000 yr and the youngest loess accumulation period started most likely after the Heinrich 3 event and lasted until the Heinrich 2 event (25,000–20,000 yr). Two main periods of permafrost occurred at approximately 60,000 and 28,000 yr bp.

Geomorphological investigations and luminescence dating in the southern part of the Khangay and the Valley of the Gobi Lakes (Central Mongolia)

Geomorphological investigations in the catchment area of the Baydragiyn river along the southern slope of the Khangay and in the Valley of the Gobi Lakes in western Mongolia provide evidence for Late Quaternary glaciations and lake-level changes. Thermoluminescence (TL) and infrared optically stimulated luminescence (IRSL) dating of aeolian and colluvial sediments from the central Khangay place the sediments that overlie fluvial and glaciofluvial terraces in the Holocene. An age of 21 ka is determined for a sand deposit overlying the terrace that is related to the last glacial ice-margin. Lacustrine sediments from higher beach lines in the Valley of the Gobi Lakes provide evidence for a slightly more humid period around 1.5 ka, and a larger extent of the lakes in the Early Holocene at about 8.5 ka, as also reported from other parts of Central Asia. Remnants of lacustrine sediments buried by alluvial gravel, and indicating a huge palaeolake in the basin of the Orog Nuur, however, date to the early stage of the last glaciation around 70 ka. Copyright © 2001 John Wiley & Sons, Ltd.

Luminescence chronology of aeolianites from the section at Givat Olga — Coastal Plain of Israel

The Eastern Mediterranean Coastal Plain of Israel is composed mainly of loam, sand and gravel of Pleistocene to Holocene age, indicating an alternation of marine, coastal and continental environments. Owing to the complexity of the numerous exposures of aeolianites (“kurkar”) and soils (“hamra”) in the elongated ridges along the coastal plain, it is difficult to set up a reliable stratigraphy. A systematic luminescence dating study was carried out on loose sand, kurkar and hamra deposits in the coastal plain between Netanya and Haifa. Sixteen samples were taken and investigated from the section at Givat Olga. The chronological results show excellent agreement between the infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) techniques, indicating that the former sand dunes were well-bleached prior to deposition. The IRSL and TL age estimates range from about 75–3 ka for the aeolianites indicating that this kurkar ridge formed during an older period of the last glaciation, likely before 50 ka.

Luminescence dating of loessic sediments from the Loess plateau, China

Loess/palaeosol sequences from the Loess plateau in China were investigated by combined infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) dating techniques in order to study the luminescence properties of the loessic sediments and to provide a direct chronological link for correlation and position of the last interglacial soil in Central Asia and the Loess plateau in China. Sensitivity changes were found for all samples through artificial bleaching of the samples. The greatest sensitivity changes, of up to 50%, were found for very old loess samples designated to be older than the Matu-yama/Brunhes magnetic boundary and hence older than 788,000±1,800 years. The upper dating limit, as investigated by the very old loess samples, ranges from 250,000 to 300,000 years, if the TL additive dose method is applied. The chronological position of the last interglacial soil S1 at the section near Lanzhou indicates luminescence age estimates ranging from 82,000 to 75,000 years for the marine-isotope stage 5 to 4 transition. However, the loess from below S1 yielded luminescence age estimates between 153,200±14,200 and 110,100±20,100 years for TL and IRSL additive dose methods, respectively. Thus, a direct correlation between the S1 and the first intercalated pedocomplex PC1 in Central Asia is most likely.