Volume 43 (2016): Issue 1 (January 2016)

Knowledge of the age of fluvial deposits is an important aspect in the understanding of river dynamics, which is pre-requisite for sustainable river management and restoration back to more natural conditions and processes. Presented here is a case study on using feldspar Infrared Stimulated Luminescence (IRSL) to date low-energy fluvial sediments that formed after correction of the Upper Rhine River in the first half of the 19^th century. A rigorous testing programme is carried out to characterise the IRSL properties of the samples, including thermal transfer, dose recovery and fading. All samples reveal complex distributions of equivalent dose, implying the presence of differential bleach-ing in the samples. It is shown that multi-grain aliquots overestimate the known-age by up-to 200 years, i.e. apparent IRSL ages are twice as old as the true age of the sediment. The use of single grains results in ages that are in excellent agreement with the expected age, therefore the age overestimation in multi-grain aliquot measurements is likely explained by signal averaging effects. While the application of single grains appears mandatory for dating young low-energy fluvial deposits, the small absolute offset associated with the multi-grain approach might be acceptable when dating sediments of such type that are older than a few 1000 years.

The Nawamis are sandstone-built circular structures, located at several sites across Southern Sinai, Egypt. They are thought to be family tombs, created by the nomadic people that inhabited the area. Archaeological age estimates fall within the Early to Late Bronze Age. Here an interesting suite of nine OSL dates of three stone pieces has been resulted, from two Nawamis at Gebel Gunna and Ain Khodra fields. Single aliquot regeneration OSL of quartz grains provided the accumulated dose. XRD was used to identify mineralogy of several tombs. Based on the estimated luminescence ages a time span from Early and late Bronze ages is obtained, while some possible later activity, due to partial (re)construction or reuse of tombs, was detected.

A set of subfossil macroremains, consisting of 118 oak (Quercus sp.) and 61 elm (Ulmus sp.) trees, was collected at five sites in the foothills of the Eastern Carpathians along the course of the Suceava river. The tree-ring widths of the subfossil samples were measured. Dendrochronological synchronization resulted in five oak chronologies, although each encompassed relatively few (2 to 4) reliably cross-dated series. Radiocarbon analysis was performed on samples from three of the floating chronologies and on an additional single oak sample. Double radiocarbon data from two of the floating chronologies allowed for improved calibration using the wiggle-match estimate of the subfossil oak remains. Radiocarbon evidence highlighted the fact that the subfossil material recovered from the fluvial deposits of the Suceava river may represent a substantial part of the Holocene, from ~700 to ~7000 years ago. When temporal distribution of ¹⁴C dated sequences from the Suceava black oaks were compared to the calibrated age ranges reported from nearby rivers (Siret, Moldova), deposition events were observed to coincide at around 0.8–0.9 ka cal BP and ~3.7–3.6 ka cal BP. The five presented floating chronologies, and especially the first ¹⁴C wiggle-matched tree-ring sequences of Ro-manian black oaks could become key building blocks in a longer regional oak tree-ring chronology for the Eastern Carpathian region.

Alluvial fans are important geomorphic archives because of its strategic location at mountain front which can provide clues to the past climate and tectonics. In general, they provide information about optimum climate condition suitable for fan formation. We provide a detailed luminescence chronology of alluvial fan in north West Bengal, India. The regional fan surface (T₄4) has been dissected by E-W trending Himalayan thrusts known as Matiali and Chalsa thrusts and have various terraces named as T₃, T₂ and youngest one as T₁. Luminescence ages suggest that the formation of the alluvial fan (regional surface) started before 171 ka and continued till 72 ka covering a time span of nearly 100 ky; suggesting of weaker monsoon at 72 ka. Matiali fault activated after 171 ky. Chalsa fault is suggested to be active during 48–41 ka. The last aggradational phase was around 6 ka which led to the formation of T_1a terrace. The study suggests that climatic fluctuation during the period were shaping the morphology of the alluvial fan, along with tectonic activities on the two faults.

The sulfide minerals from old mafic intrusion rocks from the Kola Peninsula were analyzed on stable sulfur isotopes. These samples were already dated by the Sm-Nd method. These sulfide samples were evaluated upon a geochemical composition by ICP-MS. The sulfide mineral samples were selected from the main ore-bearing rocks of the Monchetundra layered intrusion. The analyzed sulfides formed several generations of mineralization associated with primary and hydrothermal stage of formation of the deposits. Isotopic studies confirm a few consecutive stages of mineralization. These data were compared with the results of Sm-Nd dating of sulfide mineralization. The results of geochemical and geochronological studies indicate a complementarity in the context of determining the mineralization stages.

Greater warmth and precipitation over the past several decades in the High Arctic, as recorded in meteorological data, have caused shrub expansion and affected growth ring widths. The main aim of the study was to develop a tree-ring chronology of polar willow (Salix polaris Wahlenb.) from southwest Spitsbergen, attempt to explain its extreme pointer years (extremely low value of growth-ring widths) and to demonstrate the dendrochronological potential of this species. This plant is a deciduous, prostrate, creeping dwarf shrub that produces anatomically distinct annual growth rings with the consistent ring width variation. After using serial sectioning we developed rigorously cross-dated ring width chronology covering the period 1951–2011. Since the beginning of the 1980s an increase of the mean and maximum growth ring width has been observed which is consistent with the increase of both temperature and precipitation in the Arctic reported from meteorological sources. Nine negative extreme years were distinguished and explained by complex hydroclimatic drivers, which highlight the importance of availability of moisture from snowpack and spring precipitation. An additional negative factor present in the years with very low dwarf shrubs growth is rapid thawing and fast freezing during winter as well as low sunshine duration. Our results contradict the prior assumption that inter-annual tree growth variability of dwarf shrubs from polar regions is controlled simply by temperature.

Lahars are a widespread phenomenon in volcanic environments and good knowledge generally exists on contemporary, syn-eruptive lahar activity. Much less data is, by contrast, available on post-eruptive lahars and/or hydrogeomorphic processes out of extinct volcanic complexes. In this study we present a reconstruction of intra-eruptive lahar activity in Axaltzintle valley (Malinche volcano) using growth-ring records of 86 Abies religiosa trees. Based on the identification of 217 growth disturbances, field evidence and hydrological records we reconstruct a total of 19 lahars for the period 1945–2011. The reconstructed lahars were mostly triggered by moderate intensity, but persistent rainfalls with sums of at least ~100 mm. By contrast, the 1998 and 2005 lahars were presumably triggered by hurricane-induced torrential rainfalls with >100 mm in three days.

The main purpose of the interdisciplinary research described in the present paper is to determine the characteristics of ground environment changes in the Main Market Square area, and to compare these with analyses of metal artefacts. The elemental composition of metal artefacts and the degree of contamination of archaeological layers make it possible to consider both as specific indicators, including being geoindicators that are helpful in establishing the chronology of layers. Metal-artefact samples come from archaeological layers originating from different parts of the Great Weigh House. Layers were sampled, both in this region and also in a neighbouring area at the entrance to Bracka Street — trench A. They were collected from an area of archaeological excavations, which were carried out in the years 2005–2010, reaching down to a depth of 4 meters. All artefacts come primarily from cultural layers and structures - probably linked to workshops in the early medieval settlement which functioned in the area of the Main Market Square in the 12^th and early 13^th century. However, archaeological analysis of historical material allowed us to more precisely date metal arte-facts to the turn of the fourteenth and fifteenth centuries, which was confirmed by analysis of the radiocarbon age of a sample from Room R of the Great Scales, from layer 109. Average concentrations (mg/kg) of Pb of 128454 and Cu of 108610 were determined in this sample to the AAS, which significantly exceeded of the most concentration values characteristic of the layers from the Great Weigh House.

The main objective of the study is to facilitate cross-dating of sensitive tree-ring series from living European beech (Fagus sylvatica L.) trees in the absence of a regional chronology. The main idea lies in the preliminary dating of marker rings or ring patterns visually identified on the wood (before the ring-width measurements), which is independently validated through a moving correlation between a tentative reference chronology and instrumental climate records (after the ring-width measurements). Following the detection of low moving correlations, potentially misdated segments or series are re-examined and a new tentative reference chronology is constructed. The process is repeated as long as a higher correlation with climate is obtainable. The applicability of this method was investigated on three difficult-to-date sets of tree-ring series of beech trees which were growing at temperature- or precipitation-sensitive locations in under-canopy or canopy positions. A good ability of the combined method for the cross-dating was practiced on datasets almost impossible to cross-date by commonly used approaches. Highlighting the actual correlation of ring widths with climate in tree-ring series makes the cross-dating process more independent from human decisions, so the com-bined cross-dating has the potential to improve the reliability of various dendrochronological studies.

Ira trench site is in a point where, the surface trace of North Tehran Fault (NTF) joins the Mosha Fault (MF) in the north-eastern margin of Tehran and can provide important paleosismological information for Tehran. The Ira trench, were divided into 6 packages (I to VI), described, according to their composition, relative and absolute ages. Package I consists of units 23, 25, 26, 27, 28, 29, 30 and 31. The whole package I mainly belongs to Holocene, and provides essential constraints for the recent paleoearthquake activity of the EMF and NTF zone. Therefore, finding accurate ages for the units of this package is very important. Three colluvial wedges (units 23, 26, 28) are present between 20 and 36.5 m north in package I, which are assigned to 3 episodes of activity on Fault 13. Central age model (CAM) provided OSL ages of 35.0 ± 6.1, 7.3 ± 1.3, 6.4 ± 0.9 and 56 ± 6.5 ka for units 23, 26, 28 and 29, respectively.

The conflicting ages of 56 ± 6.5 and 35.0 ± 6.1 ka (for units 23 and 29, respectively) as compared to the underlying younger units suggest that these ages are overestimated. MAM provided OSL ages of 13.1 ± 4.3 and 3.5 ± 0.4 ka for units 23 and 29, respectively. The contribution of the new statistical age model of sample IRA4 to the paleoseismic data is discussed.

We found ubiquitous evidence of ongoing slope instability by analysing the variability of tree-ring eccentricity index in trees growing on three apparently relict landslide slopes in the Sudetes (Poland, Central Europe). Slow movement of these landslide bodies occurs in the present-day conditions and is recorded almost every year, although with variable intensity. Correlation of dendrochronological record with the rainfall record from a nearby station in Mieroszów for the 1977–2007 period is very poor for two deep-seated rotational slides at Mt Suchawa and Mt Turzyna but considerably better for a shallow flowslide at Mt Garbatka. While this may reflect higher permeability of heavily jointed rocks involved in deep-seated sliding this could be linked with imperfections in the rainfall record. Dendrochronology proved capable of detecting minor displacements within landslides which otherwise show no geomorphic evidence of recent activity. Therefore, claims for the entirely relict nature of the landslides are not substantiated.

European wild pear (Pyrus pyraster, syn. Pyrus communis subsp. pyraster L.) is widely distributed in Europe, but rarely studied by dendrochronologists. This preliminary study was aimed to assess the age and effect of climate on tree-ring width in the largest Polish population of P. pyraster, in Biedrusko military area (western Poland). On the basis of samples from 21 trees, a chronology (BIE) was constructed, covering 45 years (1963–2007). Mean tree-ring width in the studied trees is 1.92 mm. The performed analyses (pointer years, correlations, and response function) indicate that tree-ring width is strongly dependent on weather conditions in the year preceding formation of the tree-ring. Annual rings of pear trees were wide after cold and rainy previous summer and after rainy previous October, while in the current year, ring width was affected by insolation in February and temperature in August (positive correlations) and precipitation in May (negative correlation). The low similarity of the ring-width pattern and effect of climate on tree-ring width between this population and a wild pear population from the Bielinek Reserve, located 200 km away, indicate that tree-ring width in this species is strongly dependent on habitat and there is a need to continue dendrochronological analyses.

Heavy snowfall and extreme snow depth cause serious losses of human life and property in the northern Tianshan Mountains almost every winter. Snow cover is an important indicator of climate change. In this study, we developed five tree-ring-width chronologies of Schrenk spruce (Picea schrenkiana Fisch. et Mey) from the northern Tianshan Mountains using standard dendrochronological methods. Correlation analyses indicated that radial growth of trees in the northern Tianshan Mountains is positively affected by annual maximum snow depth. This relationship was validated and models of annual maximum snow depth back to the 18^th century were developed. The reconstruction explains 48.3% of the variance in the instrumental temperature records during the 1958/59–2003/04 calibration periods. It indicates that quasi-periodic changes exist on 2.0–4.0-yr, 5.3-yr, 14.0-yr, and 36.0-yr scales. The reconstructed series shows that maximum snow depth exhibits obvious stages change, the periods characterized by lower maximum snow depth were 1809/10–1840/41, 1873/74–1893/94, 1909/10–1929/30, 1964/65–1981/82, and the periods characterized by higher maximum snow depth were 1841/42–1872/73, 1894/95–1908/09, 1930/31–1963/64, and 1982/83–present. The lower period of annual maximum snow depth during the 1920s–1930s is consistent with the severe drought that occurred at this time in northern China. From the 1970s to the present, the maximum snow depth has increased clearly with the change to a warmer and wetter climate in Xinjiang. The reconstruction sheds new light on snow cover variability and change in a region where the climate history for the past several centuries is poorly understood.

Ecotones, as for example riparian zones, have long interested ecologists, due to their potential role in generating species biodiversity and evolutionary novelty, as well as their sensitivity to environmental changes. Along riparian areas, vegetation is recognized for its ecological importance in several ecosystemic processes. In the Central Monte Desert (central-west Argentina), Prosopis flexuosa grows in territories characterized by a permanent access to water reservoirs, e.g. along riverbanks, where the species forms the classic gallery forests. Despite the ecosystemic role of the different Prosopis species distributed in arid lands, thus far no analysis has been conducted regarding the relation between their radial growth and hydrological changes, namely streamflow variability, in riparian settings. To fill this gap of knowledge, we performed a dendrochronological analysis considering several riparian P. flexuosa trees differing in their spatial position in relation to the riverbank. Pointer years, correlation function, and regression analyses show differences in the dendrohydrological signal of the studied species, probably function of tree distance from the river. In this sense, radial growth of trees distributed near the riverbank is tightly coupled to spring-summer (September to March) stream-flow variability, whereas for farthest trees the ring development is driven by a combination of winter and spring river discharge and late-summer precipitation amount. The presented results demonstrate the potentiality of P. flexuosa, and in a broader sense of the Prosopis genus, in dendrohydrological studies.

Electron spin resonance (ESR) dating of barite has been recently developed and is now practically applied to barite extracted from sea-floor hydrothermal deposits. The evolution of the accumulated dose to barite is simulated for an actual sample of barite in sea-floor hydrothermal sulfide deposit to find that the contribution of radioactive nuclei of ²²⁸Ra series can be important for the samples younger than 300 years old. Currently, any date over 50 years should be considered a maximum value when the ²²⁸Ra content is not obtained. The method to estimate the contribution from ²²⁸Ra series has to be developed in future for those in which ²²⁸Ra is not detected. The age limit of ESR dating of barite would be 5000 to 6000 years due to the decay of ²²⁶Ra, which is also found by simulation of the accumulated dose.

Both Optically Stimulated Luminescence (OSL) dating and ¹⁴C dating are main dating method for archaeological sites, while their disagreements are quite often. In the Qaidam Basin (QB), human activity remains (HMRs) are frequently found within aeolian sediments, offering opportunities to make comparison between OSL and ¹⁴C ages, and to discuss their potential disagreements in archaeological sites. In this study, we present comparison between 18(10 of them had been published) OSL and 17 AMS ¹⁴C ages for samples from aeolian sediments in the eastern QB, including some samples from archaeological sites. Comparisons show better agreement in natural aeolian section, but more disagreements in sections with many HARs. This should be due to postdepositional anthropogenic disturbance, which can cause different influences to OSL and ¹⁴C ages. The age disagreement might display their different significances, with ¹⁴C chronology represent human activities, while OSL chronology more likely to reveal ages of original stratigraphy. Field hearth experiment was taken to check to what extent can heat from a hearth affect luminescence signals in the surrounding sediments. Results show that both OSL and Thermoluminescence signals in sediments under the hearths are not easy to be reset by the heat due to the poor downward thermal conductivity into the humid soil. This reminds the risk of OSL age overestimation for hearths. This study emphasizes the importance of cross-check between different dating methods for chronology building in archaeological contexts, and the necessity to analyze the dating materials, depositional process, and post-depositional disturbance when age disagreement is discovered.

Optically stimulated luminescence (OSL) is increasingly applied to the dating of rock surfaces. There is at present no practical way of separating pure minerals (quartz and feldspar) from hard rocks for OSL measurement without losing the grain-size dependent dosimetric information and there is little information about the performance of the single-aliquot regeneration-dose (SAR) measurement protocol on the post-infrared infrared stimulated luminescence (pIRIR) signals from rock slices. The latter is investigated here. Our data indicate that there is a systematic increase in dose response curve saturation (or D_o) with test dose size when the regeneration doses are first given in increasing order, and then decreasing order. This trend disappears if these orders are reversed. The reproducibility of dose response curves is dependent on the size of the test dose (poorer for small test dose). For rock slices given a saturation dose in the laboratory, it is observed that the sensitivity corrected pIRIR₂₉₀ signal lies close to saturation level of the dose response curve, for first IR stimulation at temperatures between 50 and 250°C. However, the pIRIR₂₉₀ signal from naturally saturated slices lies close to the laboratory saturation levels only for higher first IR stimulation temperatures e.g. 200°C or 250°C. Our data confirm earlier suggestions based on sand-grain measurements that, for older samples, accurate measurements close to saturation require that a higher first IR temperature is used.

The alpha effectiveness value (k-value) for the ESR (Electron Spin Resonance) signal due to SO₃^- in barite was revised by comparing the dose responses of the signal intensities to gamma rays and to 4 MeV He⁺ ion doses in natural sea-floor hydrothermal barite samples actually used for dating. Of the values obtained for a synthetic, a natural old, and a natural young samples, the one for the natural young sample is tentatively adopted, which is 0.053 ± 0.006, although further works are still necessary to establish this value.

The Gyaring Co Fault (GCF) is an active right-lateral strike-slip fault in central Tibet that accommodates convergence between India and Asia in the interior of the Tibetan Plateau. The average long-term slip rate of the fault remains controversial, given the absence of absolute age data of faulted geomorphic features. We have applied optically stimulated luminescence (OSL) dating to the northern segment of the GCF, revealing that the GCF has displaced alluvial fans at Aerqingsang by 500 ± 100 m since their deposition at ~109 ka, yielding a slip rate of 4.6 ± 1.0 mm/yr. A slip rate of 3.4 ± 0.4 mm/yr is inferred from analysis of an alluvial fan with an offset of 65 ± 5 m (~19 ka) at Quba site 1. The Holocene slip rate is estimated to be 1.9 ± 0.3 mm/yr, as inferred from the basal age (~8.3 ka) of terrace T1 that has a gully displacement of 16 ± 2 m at Quba site 2. These slip rates are generally lower early estimates (10–20 mm/yr), but are consistent with more recent results (2.2–4.5 mm/yr) and GPS data for other strike-slip faults in this region, indicating that deformation may be distributed across the entire Tibetan Plateau. Moreover, we suggest that the slip rate along the GCF may have decreased slightly during the late Quaternary.

In this study, measurements of electron spin resonance (ESR) signals from quartz grains from present-day river bed sediments of the Kizu River basin (western Japan) were used to estimate the mixing ratios of the possible source materials of these fluvial deposits. The dose-saturated ESR signal intensities obtained from the Al and Ti-Li centers in quartz grains were close to the range between the maximum and minimum intensities of their potential source rocks, meaning it was possible to estimate the mixing ratios of these sources. The results indicate that the dose-saturated Al and Ti-Li center ESR intensities can be used to quantitatively estimate the provenance of the sediments deposited by the Kizu River.

The coastal sediments of the South Yellow Sea (SYS) provide a record of regional land– sea interactions. This study investigated the applicability of optical dating, using coarse-grained quartz, to provide a chronology of these sediments. A 150-m-long drilling core (YZ07) was retrieved from the southwest coast of the SYS on the northern flank of the Yangtze River delta. Overall, 28 samples extracted from the upper 50 m of core YZ07 were investigated. Preheat plateau and dose recovery tests were conducted. The optically stimulated luminescence (OSL) signals were typical of quartz and they were dominated by fast components. The spread in measured equivalent doses (D_es) for each sample was generally consistent with the OSL signals being fully reset before deposition. The OSL ages generally increased with depth and indicated a 24-ka sedimentary record for the upper 50 m of the core. The age–depth relationship revealed two distinct sedimentary periods: (1) very slow sedimentation or even a depositional hiatus from the last glacial maximum (LGM) to the early Holocene (~24 to 8 ka); (2) very fast sedimentation at a rate of ~6 m/ka during the middle to late Holocene (since ~8 ka). It is speculated that sedimentation within the study area since the LGM might have been related to sea level change, delta initiation, and incised-valley fill processes.