The Tatra Mountains are located in the northernmost part of the Western Carpathians and represent a typical alpine landscape that developed during the Pleistocene glaciations. The reconstruction of glaciation events and related deposits in the mountains and their foreland have been the focus of numerous studies since the 19th century (e.g. Zejszner, 1856). However, the most important findings on the Quaternary evolution of the Tatras emerged in the second half of the 20th century as a result of geomorphological and geological studies and mapping campaigns. Based on morphostratigraphic criteria and other relative dating methods (e.g. degree of clast weathering, correlation of stratigraphic horizons and pollen analyses) the studies described the Lower, Middle and Upper Pleistocene glacial and glaciofluvial deposits, recording a complex glacial history of the Tatra Mountains (e.g. Lukniš, 1964; Klimaszewski, 1988; Halouzka, 1989; Krzyszkowski, 2002; Bińka and Nitychoruk, 2003; Lindner
In this study, we investigate the applicability of quartz and feldspar from the Tatra Mountains for luminescence dating to elucidate the Quaternary evolution of the southern foothills of the Tatra Mountains, as well as understanding its structural evolution by integrating other geological and geomorphological data (e.g. Pánek
The Tatra Mountains, extending along the Slovakian–Polish border, are the highest mountains of the Carpathian chain. They consist of the Western and Eastern Tatra Mountains, which are further subdivided into the High Tatra and Belianske Tatra Mountains (Mazúr and Luknis, 1978). The mountains form an asymmetric horst with a crystalline core in the southern part and Mesozoic rocks in the northern part. The crystalline core mainly consists of granitoids in the eastern part of the mountains and metamorphic rock in the western part. The mountains were intensively glaciated during the Pleistocene with 55 glacial systems during the Last Glacial Maximum (Zasadni and Kłapyta, 2014). Quaternary sediments are found in significant amounts in the southern foothills of the High Tatra Mountains. Their thickness is controlled by the topography of the pre-Quaternary basement and syndepositional tectonics (Halouzka in Nemčok
Geomorphological and geological data are evidence of several glaciated periods during the Pleistocene in the Tatra Mountains, interpreted to represent two to three (e.g. Lukniš, 1973; Klimaszewski, 1988) or up to eight glaciations (Halouzka, 1992; Nemčok
The valley of the Biely Váh river (downstream from the Važecká dolina valley) originates from the southeastern foothill of the Kriváň štít peak (2495 m a.s.l.) and becomes the Váh river in the south (
The Velická dolina valley extends from the foothill of the Velický štít peak (2319 m a.s.l.) located in the main ridge of the High Tatra Mountains. In the upper part of the valley, the Velický potok stream incises into granodiorites and borders our main stratigraphic site, the so-called Great Yellow Wall (GYW) in the lowest part of the valley (
The fieldwork in the southern foothills of the High Tatra Mountains in Slovakia was carried out during August 2019. The two areas were chosen based on the available exposed outcrops, which seemed suitable for the recovery of luminescence samples and the already available data from the nearby areas (Lindner
The sampling of the Biely Váh valley was concentrated on one stratigraphic site (informally named the Bee Pit after the apiculture next to the outcrop; N49.0998°, E20.0176°) that is located in a gravel pit (
Sample information acquired from the investigated study areas. Lithofacies codes are based on Krüger and Kjaer (1999).
19082 | Bee Pit | 42829 | 5439202 | Lower section | 7.1 | B3 | SiSm(ng) | 180–250 |
19083 | Bee Pit | 428289 | 5439024 | Lower section | 11.4 | B1B | SSim | 180–250 |
19084 | Bee Pit | 428292 | 5439015 | Lower section | 13.8 | B3 | SiSm(ng) | 180–250 |
19085 | Bee Pit | 428289 | 5439024 | Lower section | 11.4 | B3 | SiSm(ng) | 180–250 |
19086 | Bee Pit | 428283 | 5439047 | Lower section | 10.8 | B3 | SiSm(ng) | 180–250 |
19087 | Bee Pit | 428228 | 5438971 | Upper section | 5.4 | B12 | SiSm(ng) | 180–250 |
19088 | Bee Pit | 428228 | 5438971 | Upper section | 5.4 | B12 | SiSm(ng) | 180–250 |
19089 | Bee Pit | 428228 | 5438971 | Upper section | 5.4 | B12 | Sm(ng) | 180–250 |
19090 | Bee Pit | 428282 | 5439016 | Lower section | 2.2 | B9 | SiSm | 180–250 |
19091 | Bee Pit | 428282 | 5439016 | Lower section | 2.2 | B9 | SiSm | 180–250 |
19092 | Bee Pit | 428286 | 5439018 | Lower section | 3.6 | B5 | Sm(ng) | 180–250 |
19093 | GYW, site 1 | 439489 | 5441932 | GYW South (YS) | 1.8 | YS3 | GSm | 180–250 |
19094 | GYW, site 1 | 439489 | 5441932 | GYW South (YS) | 1.7 | YS3 | Sm | 180–250 |
19095 | GYW, site 1 | 439489 | 5441932 | GYW South (YS) | 2.2 | YS3 | GSm | 180–250 |
19096 | GYW, site 2 | 439514 | 5442023 | GYW North (YN) | 15 | YN1 | Sm | 180–250 |
19097 | GYW, site 2 | 439514 | 5442023 | GYW North (YN) | 15 | YN1 | Sm | 180–250 |
19098 | Site 3 | 439737 | 5441549 | Flood deposit | 0.24 | - | Gm | 250–355 |
19099* | Site 4 | 439677 | 5441615 | East of Velická potok | 2 | - | Gm | * |
19100 | Site 4 | 439677 | 5441615 | East of Velická potok | 2.5 | - | Sm | 180–250 |
19101 | Site 5 | 439605 | 5441701 | West of Velická potok | 2.6 | - | Sh | 90–180 |
19102 | Site 5 | 439605 | 5441701 | West of Velická potok | 2.5 | - | Sh | 180–250 |
19105 | Site 6 | 439775 | 5441345 | Modern Analogue (MA) | 0 | - | Sm | 180–250 |
19106 | Site 6 | 439775 | 5441345 | Modern Analogue (MA) | 0.03 | - | Sm | 250–355 |
19103* | Site 7 | 440614 | 5436964 | Distant MA | 0 | - | Sm | * |
19104* | Site 7 | 440614 | 5436964 | Distant MA | 0.12 | - | Sm | 90–180 |
20026 | GYW, site 2 | 439514 | 5442023 | Saturated sample | 15 | YN1 | Boulder | 180–250 |
20028 | Site 8 | 439819 | 5442867 | Moraine | 5 | - | DmC | 180–250 |
These samples are excluded from feldspar age calculations due to insufficient material.
The following descriptions and interpretations are based on the work by Bejarano Arias (2020) and van Wees (2020), where more details can be found.
The lower outcrop has a width of c. 45 m and a height of 13.6 m, while the upper outcrop has a height of around 6 m. The two sections comprise 13 lithostratigraphic units and are separated vertically by around 20 m, where sediments are inaccessible due to extensive excavation-derived slope deposits as well as vegetation cover (
The
The
The sand layers are dominantly massive, indicating that the depositional process could have occurred rapidly. The presence of localised structures like silt lenses and normal grading indicated that their deposition had a fluvial or current component. This change was indicating the transition from hyperconcentrated to normal flow, which can occur during falling discharges, as a result of formerly suspended sediments (Maizels, 1989). Though information on the sediments from between the lower and the upper sections is missing, based on the setting and appearance of the site, we find it most likely that the upper units (B11–B13) are younger and stratigraphically overlie the lower units (B1–B10). However, based on field observations, we cannot exclude the possibility that the lower units form a (younger) terrace cut into the upper sediments.
Sites 1–2 are located at the GYW, where sediments are exposed due to a mass movement (
At Site 1, on the south peripheral of the GYW, four distinct lithological units were identified (
Unit YS3 contains some channelised lenses, is massive and matrix supported and therefore interpreted as a hyperconcentrated flow (Benn and Evans, 2010; Germain and Ouellet, 2013
At Site 2, on the north peripheral of the GYW, around 13 meters lower than Site 1, a small section (YN1) with an area of 1.5 by 2 m was accessible for sampling. The exposed sediments consist of massive, clast-and matrix-supported boulders with a matrix composed of medium- to coarse-sized sand and granules. The boulders are strongly weathered to decomposed (
Sites 3–6 are all located in the proximity of the Velický potok river. At the time of the fieldwork (August 2019), its stream was relatively turbulent, but the amount of suspended material in the water was low.
Site 3 is situated east of the river and makes up an old riverbed and side branch of the main modern stream of the Velický potok river. Sample 19098 was taken from massive medium to coarse sand at this site (
At Site 4, east of the Velický potok river, an outcrop was found on a higher level next to the river (2–2.5 m above the present-day riverbed) in what appears to be a ca. 8-m-high ridge along the valley. Two small sections of 50 by 50 cm were dug, and samples 19099 and 19100 were taken, one in each section. The material consisted of loose, massive coarse sand to fine gravel with some large boulders (>1 m) (
Site 5 is an outcrop with an area of 3.5 by 5 m, positioned west of and 2.5 m above the present-day Velický potok riverbed. The site represents the lowest part of the ridge of which the GYW is part of in the south. The exposed sediment is laminated and consists of alternating thick laminae of medium and coarse sand. Samples 19101 and 19102 were taken with a 1.5 m horizontal distance (
Horizontally laminated medium and coarse sand suggests upper and lower flow regime plane bed conditions common in glacifluvial environment (e.g. Russell, 2007). In addition, the absence of gravel and clasts points to a relatively calm depositional environment.
Site 6 is located in the riverbed of the Velický potok, and modern analogue samples were extracted from here. At the time of sampling of samples 19105 and 19106, this part of the riverbed was dry and around 2.5 m wide; it is presumed that it deposited at a higher water level in the recent past (
Site 7 is located around 4.5 km downstream from Site 6. Samples 19103 and 19104 were sampled 2 m from the active river in medium to coarse sand and are referred to as distant modern analogues.
Site 8 is a moraine ridge in the upper part of the Velická dolina valley. Sample 8 was taken from a natural outcrop ca. 1.5 m wide and 1.4 m high located on the slope some 25 m above the left bank of Velický potok creek (
The samples for luminescence dating were taken by horizontally hammering opaque PVC tubes into the vertically exposed sediments. In total, 27 samples were collected (
The recovered luminescence samples were opened and prepared under subdued red light in the Lund Luminescence Laboratory at Lund University, Sweden. The sediment from the middle part of the tube was wet sieved, and the 180–250 μm fraction was extracted for most of the samples. Only for four samples from the Velická dolina valley, a finer (90–180 μm) or coarser grain size (250–355 μm) had to be used due to the sediment's grain size distribution (
The obtained feldspar went into a test tube with LST Fastfloat at 2.58 g/cm3 to separate K-feldspar from plagioclase. The K-feldspar fraction was treated with HF (10%) for 20–40 min depending on grain size and subsequently with HCl (10%) for 40 min. Afterwards, it underwent the same sieving procedure as quartz.
For dose rate determination, the samples were weighed after being heated to 105°C for 24 h to determine the dry weight. After that, they were ignited at 450°C for 24 h to remove organic matter. After being crushed to silt size (<20 μm), the sediment was mixed with beeswax and cast into a standard geometry (cups) for high-resolution gamma spectrometry measurements (Murray
The luminescence measurements were performed using Risø ‘TL/OSL DA-20’ readers (Bøtter-Jensen
The determination of equivalent dose (
The SAR measurement sequence included preheating to a temperature of 220°C for 10 s, followed by stimulation using IR LEDs at 125°C for 100 s to monitor and deplete the IRSL signal from feldspars. Optical stimulation was carried out using blue LEDs for 40 s at 125°C. Sensitivity changes were corrected using the OSL response to a test dose (∼10–20% of the assumed natural dose) throughout the SAR protocol. All measurements included intrinsic tests (recycling and recuperation) (Murray and Wintle, 2003). Every SAR cycle was followed by a 40-second high-temperature clean-out at 280°C.
Preheat plateau (PHP) tests and dose recoveries at different temperature combinations, ranging from 180°C to 260°C for the first half of the cycle (preheat) and 160°C to 220°C for the second half (cutheat) following the SAR protocol (Murray and Wintle, 2000, 2003), were carried out on samples 19082, 19084, 19086 and 19089 to determine the most suitable preheat temperature to use for the rest of the quartz samples. Most tests were carried out on sample 19082 because it provided enough material and it belongs to unit 3 of the Bee Pit, from which several of the other samples were also taken. Dose recovery tests were conducted on aliquots that were exposed to natural light in a window (at the Department of Geology in Lund, Sweden) for 3–5 days in January and then given a known dose in the laboratory. Dose recovery was performed both for the SAR protocol and differential OSL with a given dose of 133 Gy and a test dose of 16–25 Gy. Different integration intervals for peak and background were tested, representing both early and late background subtraction. The dose–response curves for quartz samples were constructed by using exponential curve fitting function in Analyst v4.57.
Differential OSL (Jain
To get a better understanding of the luminescence behaviour of quartz from the Tatra Mountains, we investigated the thermal stability of the quartz OSL signal by performing a pulse–anneal experiment on one representative sample (three aliquots per sample) from each investigated site: 19082 from the Bee Pit, 19095 from the GYW and 19104 from Site 7, which also represents a modern analogue. Electrons were evicted from the OSL traps by heating the samples to 500°C, after which a laboratory dose of 80 Gy was given. The aliquots were then preheated for 10 s between 220°C and 440°C at 20°C increments, followed by OSL measurement at 125°C for 40 s. A final 500°C heat treatment was performed after each run to remove any remaining signals. The correction for sensitivity changes during the pulse–annealing experiments was made using OSL response to a test dose of 8 Gy. The luminescence remaining after heating to each temperature was normalised to the initial value. For comparison, the same experiments were conducted on two aliquots of the Risø calibration quartz (batch 123), which is known for a strong fast component (Hansen
We also analysed the individual components of the OSL signal using linear modulated (LM) OSL measurements on the same samples as for the pulse–anneal experiment. For comparison, we also performed an LM measurement on the Risø calibration quartz (Batch 123) and calculated the fast ratio according to Durcan and Duller (2011) for all quartz samples, except sample 19103.
For the LM-OSL measurements, the quartz grains were first irradiated with a laboratory beta dose of 50 Gy, after which a 200°C preheat for 10 s was applied. The LM-OSL signals were subsequently measured for 1000 s at 125°C while linearly increasing the power of the blue LEDs from 0 mW/cm2 to 65 mW/cm2. For the background determination, one additional blank aliquot was measured in the same manner as the quartz grains. The deconvolution of the LM–OSL curves was performed using the fit_LMCurve function of the R Luminescence package (Kreutzer, 2022 in, Kreutzer
All feldspar measurements were performed using small 2-mm (50–100 grains) aliquots (
To estimate the bleachability of the pIRIR225 signal from the Tatra samples and determine the residual dose, we performed a bleaching experiment on 18 aliquots of the feldspar sample 19087. The aliquots were exposed to artificial sunlight in a Hönle SOL2 solar simulator for different lengths of time: 1, 5, 20, 60 and 20,960 min (2 weeks). Subsequently, the relative bleaching of the IR50 and pIRIR225 signals was determined using the same protocol as for the
For the calculation of the ages, the average environmental dose rate since the time of deposition needs to be determined. Consideration must be taken of changing water content or nuclide leaching, which will affect the dose rate. In this study, the dose rate is assumed to have remained constant over time. The water content or soil moisture impact is related to the determination of dose rate and subsequent age estimation. Though important values for the age calculation, they are difficult to determine exactly since sedimentological, topographic and climatic conditions from the study area and their variation over time and depth must be accounted for (Rosenzweig and Porat, 2015).
To assess the sediment density and water content, the 100 cm3 soil sample rings were weighed in their natural state and after 24 h of saturation and 24 h at 105°C in an oven, respectively. The field water content (wcf) and the saturated water content (wcs) were calculated as mass% of the dry weight. The dry weight was also used to determine the sediment density.
An estimate of the average water content since the time of deposition is required for determination of the environmental dose rate. As no reliable data of the past water content in the foothills are available, the expected water content (wce) was estimated. This is carried out assuming that the wce is in between the wcf and the wcs, following the calculation method in Nelson and Rittenour (2015):
Ages for both quartz and feldspar were calculated using DRAC v1.2 dose rate and age calculator (Durcan
The IR/B tests showed that the quartz grains were contaminated with feldspar. The IR/B ratio was significant (>10%) for all but two samples (19094 and 19098B). For most samples, the ratio ranged from 16% to 46%; however, samples 19088 and 19105 displayed much higher values, ranging from 200 to 2000%. The samples were therefore measured with post-IR blue (Roberts and Wintle, 2001) or pulsed stimulation (Ankjærgaard
Using early background subtraction to enhance the fast signal component (Cunningham and Wallinga, 2010) led to large uncertainties in the dose determinations and higher rejection of aliquots. Doses and dose recovery ratios calculated with early background (
Analysis of the quartz OSL signal decay curves showed that the quartz signal is dim and that it had a weak fast signal component with significant contributions of medium and slow components (
OSL parameters calculated from the quartz extracts using linear modulation compared to other values from literature.
19082 | Fast | 22.4 ± 4.9 | 1.4 × 10−16 | 1 |
Slow1 | 1.8 ± 0.2 | 1.2 × 10−17 | 0.09 | |
Slow2 | 0.17 ± 0.003 | 1.1 × 10−18 | 0.01 | |
Slow3 | 0.018 ± 0.004 | 1.1 × 10−19 | 0.001 | |
Slow4 | 0.0004 ± 0.0003 | 2.5 × 10−20 | 0.0002 | |
19095 | Fast | 9.6 ± 3.2 | 6.1 × 10−17 | 1 |
Medium | 0.94 ± 0.1 | 6.0 × 10−18 | 0.1 | |
Slow2 | 0.12 ± 0.008 | 7.8 × 10−19 | 0.01 | |
Slow3 | 0.017 ± 0.0008 | 1.2 × 10−19 | 0.002 | |
Slow4 | 0.004 ± 0.00009 | 2.9 × 10−20 | 0.0006 | |
19104 | Fast | 1.6 ± 0.3 | 6.2 × 10−18 | 1 |
Slow1 | 0.08 ± 0.04 | 5.0 × 10−19 | 0.05 | |
Slow3 | 0.005 ± 0.0003 | 3.1 × 10−20 | 0.003 | |
Calib. quartz | Fast | 2.7 ± 0.09 | 1.6 × 10−17 | 1 |
Slow4 | 0.0007 ± 0.00003 | 4.5 × 10−21 | 0.0003 | |
Jain |
Fast | 2.5 ± 0.2 | 2.3 × 10−17 | 1 |
Medium | 0.62 ± 0.05 | 5.6 × 10−18 | 0.2 | |
Slow1 | 0.15 ± 0.03 | 1.3 × 10−18 | 0.06 | |
Slow2 | 0.023 ± 0.005 | 2.1 × 10−19 | 0.01 | |
Slow3 | 0.0022 ± 0.0002 | 2.1 × 10−20 | 0.001 | |
Slow4 | 0.00030 ± 0.00001 | 2.8 × 10−21 | 0.0001 | |
Durcan and Duller (2011) | Fast | n.a. | 2.6 × 10−17 | 1 |
Medium | n.a. | 4.3 × 10−18 | 0.16 | |
Slow1 | n.a. | 1.1 × 10−18 | 0.04 | |
Slow2 | n.a. | 3.0 × 10−19 | 0.01 | |
Slow3 | n.a. | 3.4 × 10−20 | 0.001 | |
Slow4 | n.a. | 9.1 × 10−21 | 0.0003 |
The presented results represent the average values of two measured aliquots. For comparison, the values by Jain
The results of the pulse annealing experiment are shown in
Despite the unsuitable luminescence characteristics, a few dose estimates were made for some samples from the Bee Pit and the Velická dolina valley following the standard SAR protocol (
OSL doses, dose rates and ages for the quartz samples.
19082 | 18 | Differential OSL | 268 ± 58 | 2.6 ± 0.1 | 104 ± 23 |
12 | Pulsed OSL | 102 ± 6 | 40 ± 3 | ||
19083 | 3 | Standard SAR | 143 ± 27 | 2.7 ± 0.1 | 53 ± 10 |
19084 | 6 | Standard SAR | 160 ± 41 | 2.1 ± 0.1 | 77 ± 20 |
19085 | 3 | Standard SAR | 103 ± 21 | 2.4 ± 0.1 | 42 ± 9 |
19090 | 3 | Standard SAR | 96 ± 11 | 2.6 ± 0.1 | 38 ± 5 |
19091 | 3 | Standard SAR | 186 ± 55 | 3.2 ± 0.1 | 58 ± 17 |
19092 | 3 | Standard SAR | 114 ± 40 | 3.3 ± 0.2 | 35 ± 12 |
19102 | 12 | Pulsed OSL | 30 ± 6 | 2.3 ± 0.2 | 13 ± 3 |
Note that due to the low number of aliquots and the unsuitable characteristics of the quartz, the final ages are considered unreliable.
The obtained environmental dose rate for feldspar ranges from 4.39 ± 0.26 Gy/ka to 1.78 ± 0.14 Gy/ka, with similar dose rate averages in the Biely Váh valley (3.34 ± 0.17 Gy/ka) and the Velická dolina valley (3.38 ± 0.22 Gy/ka) (
Concentration of radioactive elements in the sampled sediments (from gamma spectrometry) and the dose rate from cosmic radiation to each sample (as calculated in DRAC v1.2 (Durcan et al., 2015)).
19082 | 1.49 ± 0.58 | 5.87 ± 0.15 | 2.52 ± 0.04 | 0.14 ± 0.01 | 3.33 ± 0.17 | 27 |
19083 | 0.96 ± 0.45 | 6.55 ± 0.13 | 2.42 ± 0.05 | 0.10 ± 0.01 | 3.21 ± 0.16 | 24 |
19084 | 0.48 ± 0.17 | 4.98 ± 0.08 | 1.91 ± 0.03 | 0.07 ± 0.01 | 2.70 ± 0.15 | 19 |
19085 | 0.92 ± 0.54 | 5.11 ± 0.14 | 2.23 ± 0.04 | 0.10 ± 0.01 | 2.99 ± 0.16 | 23 |
19086 | 2.43 ± 1.24 | 8.48 ± 0.33 | 2.86 ± 0.10 | 0.09 ± 0.01 | 3.87 ± 0.23 | 26 |
19087 | 1.22 ± 0.42 | 6.96 ± 0.12 | 1.99 ± 0.04 | 0.16 ± 0.02 | 2.93 ± 0.15 | 29 |
19088 | 4.23 ± 0.84 | 9.35 ± 0.23 | 2.46 ± 0.05 | 0.17 ± 0.02 | 4.03 ± 0.20 | 26 |
19089 | 1.04 ± 0.21 | 5.60 ± 0.08 | 2.52 ± 0.03 | 0.17 ± 0.02 | 3.41 ± 0.16 | 20 |
19090 | 0.74 ± 0.71 | 5.97 ± 0.18 | 2.32 ± 0.05 | 0.21 ± 0.02 | 3.07 ± 0.17 | 29 |
19091 | 2.08 ± 0.39 | 8.79 ± 0.11 | 2.59 ± 0.03 | 0.21 ± 0.02 | 3.70 ± 0.17 | 27 |
19092 | 2.20 ± 0.79 | 7.27 ± 0.21 | 2.74 ± 0.05 | 0.20 ± 0.02 | 3.53 ± 0.18 | 36 |
19093 | 3.28 ± 0.34 | 12.0 ± 0.17 | 2.56 ± 0.04 | 0.20 ± 0.02 | 4.24 ± 0.23 | 21 |
19094 | 2.85 ± 0.64 | 12.3 ± 0.19 | 2.48 ± 0.05 | 0.19 ± 0.02 | 4.39 ± 0.26 | 13 |
19095 | 2.38 ± 0.45 | 10.6 ± 0.13 | 2.29 ± 0.03 | 0.19 ± 0.02 | 3.78 ± 0.21 | 21 |
19096 | 3.60 ± 0.44 | 11.6 ± 0.12 | 2.47 ± 0.04 | 0.06 ± 0.01 | 3.80 ± 0.20 | 31 |
19097 | 1.61 ± 0.86 | 13.5 ± 0.24 | 2.21 ± 0.05 | 0.11 ± 0.01 | 3.41 ± 0.21 | 31 |
19098 | 1.15 ± 0.49 | 6.80 ± 0.14 | 2.18 ± 0.05 | 0.27 ± 0.03 | 3.48 ± 0.23 | 23 |
19100 | 2.94 ± 0.58 | 12.1 ± 0.17 | 2.09 ± 0.05 | 0.17 ± 0.02 | 3.75 ± 0.21 | 23 |
19101 | 2.39 ± 0.60 | 11.8 ± 0.17 | 2.32 ± 0.05 | 0.18 ± 0.02 | 3.48 ± 0.23 | 30 |
19102 | 1.39 ± 0.72 | 8.57 ± 0.19 | 2.31 ± 0.05 | 0.17 ± 0.02 | 3.29 ± 0.20 | 29 |
19104 | 1.50 ± 0.25 | 6.53 ± 0.07 | 1.81 ± 0.03 | 0.29 ± 0.03 | 2.43 ± 0.20 | - |
19105 | 1.06 ± 0.30 | 6.68 ± 0.15 | 1.89 ± 0.04 | 0 (surface) | 1.78 ± 0.14 | - |
19106 | 1.06 ± 0.30 | 6.68 ± 0.15 | 1.89 ± 0.04 | 0.31 ± 0.03 | 2.80 ± 0.20 | 49 |
20028 | 1.18 ± 0.27 | 10.16 ± 0.15 | 2.44 ± 0.04 | 0.15 ± 0.02 | 3.72 ± 0.17 | 15 |
The total dose rate includes the contribution from 12.5% internal K in feldspar. WCe corresponds to the chosen water content, and we use a 5% uncertainty.
Note that the dose rate has not been determined for sample 19026.
The measured K-feldspar IRSL signal was significantly brighter than quartz signal; moreover, the IRSL signal of pIRIR225 measurements was brighter than the IR50 signals. Fading measurements of the IR50 signal yielded g-values ranging from 1.6%/decade to 11.5%/decade, while for the pIRIR225, the g-values were lower, varying 0.1–3.3%/decade (
Results of the IR50 and pIRIR225 measurements: g-values, feldspar dose estimates, the number aliquots with De < 2D0 compared to the total number of accepted aliquots and the uncorrected and corrected ages.
19082 | Unit 3 | 6.71 ± 0.1 | 2.23 ± 0.3 | 414 ± 15 | 868 ± 86 | 12(12)/12 | 12(1)/12 | 125 ± 7.8 | 261 ± 29 | 278 ± 18 | 326 ± 38 |
19083 | Unit 1B | 4.82 ± 0.7 | 1.56 ± 0.1 | 351 ± 14 | 844 ± 116 | 12(12)/12 | 12(1)/12 | 109 ± 7.2 | 263 ± 39 | 185 ± 28 | 308 ± 51 |
19084 | Unit 3 | 9.83 ± 0.2 | 2.84 ± 0.2 | 348 ± 14 | 741 ± 80 | 12(12)/12 | 12(2)/12 | 129 ± 8.7 | 275 ± 33 | 624 ± 82 | 368 ± 46 |
19085 | Unit 3 | 6.52 ± 0.1 | 1.66 ± 0.6 | 317 ± 11 | 760 ± 76 | 12(12)/12 | 12(1)/12 | 106 ± 6.8 | 254 ± 29 | 230 ± 16 | 300 ± 39 |
19086 | Unit 3 | 1.66 ± 0.2 | 0.09 ± 0.1 | 387 ± 16 | 812 ± 105 | 12(12)/12 | 12(0)/12 | 100 ± 7.3 | 210 ± 30 | 117 ± 8.7 | 212 ± 29 |
19087 | Unit 12 | 5.06 ± 0.3 | 1.48 ± 0.1 | 351 ± 13 | 788 ± 73 | 12(12)/12 | 12(2)/12 | 120 ± 7.6 | 269 ± 29 | 208 ± 16 | 311 ± 31 |
19088 | Unit 12 | 5.85 ± 0.2 | 0.81 ± 0.6 | 326 ± 11 | 776 ± 74 | 12(12)/12 | 12(1)/12 | 81 ± 4.9 | 193 ± 21 | 156 ± 12 | 208 ± 27 |
19089 | Unit 12 | 5.05 ± 0.02 | 1.99 ± 0.02 | 372 ± 14 | 850 ± 91 | 12(12)/12 | 12(2)/12 | 109 ± 6.6 | 249 ± 29 | 188 ± 11 | 304 ± 36 |
19090 | Unit 9 | 5.71 ± 0.4 | 2.16 ± 0.1 | 354 ± 13 | 763 ± 73 | 12(12)/12 | 12(1)/12 | 115 ± 7.8 | 248 ± 28 | 219 ± 22 | 308 ± 31 |
19091 | Unit 9 | 8.69 ± 1.1 | 0.37 ± 0.4 | 360 ± 13 | 710 ± 58 | 30(30)/30 | 30(8)/30 | 97.3 ± 5.7 | 192 ± 18 | 318 ± 185 | 199 ± 19 |
19092 | Unit 5 | 5.26 ± 0.3 | 0.70 ± 0.4 | 465 ± 20 | 949 ± 123 | 12(12)/12 | 12(2)/12 | 132 ± 8.6 | 269 ± 38 | 236 ± 19 | 287 ± 39 |
19093 | Site 1 | 8.01 ± 0.6 | 1.05 ± 0.3 | 338 ± 15 | 636 ± 64 | 12(12)/12 | 12(5)/12 | 79.5 ± 5.5 | 150 ± 17 | 219 ± 50 | 165 ± 19 |
19094 | Site 1 | 9.43 ± 0.5 | 3.04 ± 0.1 | 304 ± 14 | 611 ± 49 | 12(11)/15 | 12(7)/13 | 69.9 ± 5.2 | 139 ± 14 | 266 ± 105 | 188 ± 21 |
19095 | Site 1 | 4.83 ± 0.3 | 2.06 ± 0.2 | 325 ± 13 | 709 ± 85 | 12(12)/12 | 12(5)/13 | 86.1 ± 5.9 | 188 ± 25 | 145 ± 12 | 231 ± 29 |
19096 | Site 2 | 7.20 ± 0.6 | 1.52 ± 0.2 | 346 ± 14 | 770 ± 72 | 29(29)/30 | 29(9)/30 | 90.9 ± 6.1 | 202 ± 22 | 204.5 ± 34 | 234 ± 24 |
19097 | Site 2 | 7.25 ± 1.1 | −0.41 ± 0.1 | 330 ± 12 | 798 ± 88 | 12(12)/15 | 12(3)/18 | 96.7 ± 6.9 | 234 ± 30 | 234 ± 83 | * |
19098 | Site 3 | 8.61 ± 0.8 | 3.31 ± 0.2 | 134 ± 4.2 | 361 ± 22 | 12(12)/12 | 12(10)/12 | 38.5 ± 2.9 | 103 ± 9.5 | 116 ± 35 | 145 ± 14 |
19100 | Site 4 | 4.56 ± 0.6 | 1.43 ± 0.2 | 306 ± 15 | 839 ± 122 | 12(12)/12 | 12(2)/12 | 81.7 ± 6.1 | 224 ± 35 | 130 ± 14 | 257 ± 41 |
19101 | Site 5 | 11.49 ± 0.3 | 1.65 ± 0.2 | 131 ± 4.1 | 506 ± 37 | 12(12)/14 | 12(7)/12 | 37.7 ± 2.8 | 146 ± 14 | 307 ± 118 | 172 ± 17 |
19102 | Site 5 | 7.49 ± 0.9 | 2.60 ± 0.2 | 96.0 ± 3.1 | 387 ± 32 | 33(33)/33 | 33(22)/35 | 29.1 ± 2.0 | 117 ± 12 | 69 ± 15 | 152 ± 15 |
19105 | Site 6 | 10.77 ± 1.0 | 2.98 ± 0.3 | 31.5 ± 1.5 | 109 ± 7.0 | 12(12)/15 | 12(9)/18 | 17.7 ± 1.6 | 61.6 ± 6.3 | 79 ± 37 | 82 ± 10 |
19106 | Site 6 | 6.74 ± 0.04 | 1.64 ± 0.1 | 56.2 ± 1.9 | 183 ± 5.8 | 12(12)/15 | 12(9)/18 | 20.1 ± 1.6 | 65.4 ± 5.2 | 42 ± 3.5 | 77 ± 5.7 |
20026 | Site 2 | 5.42 ± 0.41 | 0.66 ± 0.25 | 453 ± 10 | 737 ± 47 | 5(5)/5 | 5(5)/5 | n/a | n/a | n/a | n/a |
20028 | Site 8 | 4.89 ± 0.83 | 0.88 ± 0.41 | 18.4 ± 3.9 | 55.6 ± 5.6 | 12(12)/12 | 12(12)/12 | 5.0 ± 1.1 | 15.0 ± 1.7 | 7.6 ± 2.0 | 16.1 ± 1.9 |
Corrected age is not calculated due to a negative g-value. For dose rates, see
The results of the dose recovery test showed that the best ratios (close to 1) are obtained from the pIRIR225 signal (
The doses for the non-modern samples range from 96.0 ± 3.1 Gy to 465 ± 20 Gy for IR50 and from 387 ± 32 to 949 ± 123 Gy for pIRIR225 (
The uncorrected ages from the Biely Váh valley range from 81 ± 4.9 ka to 132 ± 8.6 ka for IR50 and from 192 ± 18 ka to 275 ± 33 ka for the pIRIR225 signal. The overall lower uncorrected ages at the Velická dolina valley range from 17.7 ± 1.6 ka to 96.7 ± 6.9 ka for IR50 and from 61.6 ± 6.3 ka to 234 ± 30 ka for pIRIR225. The corrected ages for both valleys are between 1 and 1.7 times higher for pIRIR225 than the uncorrected ages, while for the IR50 ages, these values are between 1.2 and 8.1 times higher.
The results of the bleaching test of sample 19087 show that the IR50 signal bleaches at a significantly faster rate than the pIRIR225 signal (
Samples 19105 and 19106 are modern analogues, taken to evaluate bleaching and residual doses in the present-day fluvial environment. Sample 19105 was taken at the surface and 19106 was taken 3 cm below. Most aliquots from both samples do show signals and thus not a zero dose. Instead, the
Even though several variations of dose estimate measurements were performed on the quartz samples, post-IR blue OSL (Roberts and Wintle, 2001), pulsed OSL (Ankjærgaard
The decay curve shape (
The obtained quartz ages ranged from 40–60 ka (
In this study, it was observed that feldspar is more favourable for luminescence dating than quartz in terms of signal characteristics. However, there are some features of the feldspar that need to be considered when assessing the results, such as bleaching, fading and saturation.
A prerequisite for accurate luminescence dating is that the analysed sediment was effectively bleached at the time of deposition (Murray
The modern analogues (sample 19105 and 19106) are presumed to have been deposited when the water level of the Velický potok river was at least ∼25 cm higher than at the time of sampling. Given the proximity to the present riverbed and the appearance of the site, this high-flow event is believed to be recent, perhaps during spring snowmelt or a heavy rain within the last (few) years (Kotarba, 2007). The sediment is therefore presumed to be young and should theoretically contain a dose close to zero. However, the modern analogue samples 19105 and 19106 reveal relatively high natural IR50 and pIRIR225
Results of the SOL2 bleaching experiment for sample 19087.
0 (Natural) | 232.8 ± 2.8 | 6.49 ± 0.08 | 587.8 ± 19.4 | 8.88 ± 0.39 |
1 | 45.4 ± 8.7 | 1.55 ± 0.27 | 311.7 ± 31.7 | 7.38 ± 0.52 |
5 | 6.8 ± 0.3 | 0.24 ± 0.01 | 92.7 ± 4.4 | 3.04 ± 0.12 |
20 | 3.3 ± 0.2 | 0.12 ± 0.01 | 29.5 ± 0.7 | 1.06 ± 0.02 |
60 | 2.2 ± 0.1 | 0.08 ± 0.00 | 16.3 ± 0.7 | 0.60 ± 0.03 |
20160 | 0.5 ± 0.0 | 0.02 ± 0.00 | 4.8 ± 0.3 | 0.17 ± 0.01 |
Shown are the calculated
One of the most used methods to determine whether the pIRIR signal is likely to have been fully reset is the comparison with quartz signals or other IR signals that have different sensitivities to daylight. It is known that the IR50 signal bleaches more rapidly in sunlight than IR signals stimulated at elevated temperatures (Thomsen
Subtracting the residual dose could potentially correct for any dose (age) overestimation produced by an unbleachable dose. However, when the residual values (
The recent transportation of sediment from the Tatra Mountains by a river provides better bleaching conditions than the sediment transportation in a glacial environment characterised by mass movements and hypercontracted flows. One could argue, therefore, that the modern analogues would be a better measure than the bleaching experiment residual for the effect of incomplete bleaching for the old sediments and that subtracting a dose of that magnitude from each determined
It is in this context interesting to note that the sampled moraine (Site 8, sample 20026) seems to consist of effectively bleached material. At least its age (15.0 ± 1.1 ka, uncorrected pIRIR225) agrees with cosmogenic exposure ages from a similarly situated moraine in a nearby valley (20.0 ± 1.0–16.7 ± 0.7 ka; Makos
To evaluate potential incomplete bleaching for the older (higher dose) sediments, we can also observe dose distributions and compare the ages within units. The dose distributions of samples 19091, 19096 and 190102 (
The number of samples from the Bee Pit and the GYW also allowed us to compare ages from the same units, which should depict a similar age. Though the numerical uncertainty of each age is relatively large (12% on average), there is a scatter of ages within units, and not all sample ages from one and the same unit overlap within 2σ (
In terms of bleaching, we conclude that most of our samples do suffer from incomplete signal resetting and thus overestimate the true age. Therefore, the calculated ages should, in this case, be considered as maximum ages. The degree of age overestimation varies, though, and the youngest age in a specific unit may be considered the age closest to the true age of that unit.
Anomalous fading could be responsible for underestimating the equivalent doses and making the ages seem younger than they truly are, hampering their accuracy (Banerjee
The g-values of both the IR50 and the pIRIR225 signals are higher than those of some other studies, where the IR50 g-value generally ranges from 1 to 4%/decade, while for the pIRIR225 signal, the g-value varies from 0 to 1.5%/decade (e.g. Thomsen
The overall high g-values of the IR50 and some high outliers of pIRIR225 g-values also resulted in ages with higher errors as the large fading correction made the age more uncertain. Ideally, the corrected IR50 and the uncorrected pIRIR225 ages should yield similar results, given that the pIRIR225 minimises the fading effect (
Another important characteristic of these feldspar samples is saturation. Wintle and Murray (2006) stated that if the samples have doses >2*D0 and lie in the dose region where the laboratory growth curve starts to flatten out, the ages could potentially be older than is displayed and the
The process of estimating and evaluating the ages needs to consider all the features that have been discussed earlier, such as insufficient bleaching, saturation and number of aliquots, as well as the environmental dose rates, all of which have a clear impact on the final result. Several of the samples are not ideal in this context as they suffer from incomplete bleaching and/or have high doses close to saturation. Here, we will use the postulations outlined in Section 6.2 to evaluate the ages and conclude which ones were found the most reliable.
Based on the relatively low fading rates and the increased uncertainty that would be created when correcting for fading, we conclude that the uncorrected pIRIR225 signals would present the most reliable ones for age calculation of the different luminescence techniques applied.
The environmental dose rates are fairly consistent in the two study areas, and the largest uncertainties related to that are estimation of average water content since the time of deposition and, for some samples, heterogeneous sediments, for example, proximity to clasts. To evaluate the effect of changing water content, we calculated ages for three of the samples with different water content: completely dry (wc = 0%) and oversaturated (wc = 50%), see
Considering the larger stratigraphic context, a trend of age decrease from lower to upper units at the two main sites was expected: the Bee Pit and the GYW (Sites 1 and 2). Based on the arguments previously discussed, we can identify the Bee Pit samples that are likely to be most reliable and compare those stratigraphically. Sample 19091 (192 ± 18 ka) from unit B9 would, in this case, present the most reliable one, being the youngest age of its unit and having most aliquots and the least
At the GYW, the pIRIR225 ages from the upper units (139–188 ka; samples 19093–19095 from unit Y3 at Site 1) are younger than those of the samples from the lower unit at Site 2 (202–234 ka; samples 19096 and 19097), though the large errors lead to a partial overlap (
Most of the measured aliquots for sample 19098 displayed
The Quaternary deposits on the southern Tatra foreland have been studied since the beginning of the nineteenth century (e.g. Zejszner, 1856); however, their chronostratigraphy is poorly established due to the lack of numerical dating. Although the chronology of the Tatra Mountains was significantly improved in the last two decades (e.g. Makos
It is noteworthy that the ages from the Bee Pit (210 ± 30 ka) seem to largely agree with the age from Site 2, sample 19096 at the Velická dolina valley (202 ± 22 ka) where both are interpreted as hyperconcentrated flows. Other ages that overlap within 2 sigma are the ages from sample Site 1 (150 ± 17 ka and 139 ± 14 ka) and 5 (117 ± 12 ka), both from the GYW where Site 1 represents the top section and Site 5 is deposited and pasted on the lower layer(s). Assuming these sites truly formed during the same period, this could suggest a fast incision rate of the Velická dolina valley, where Site 1 is likely deposited before the incision and Site 5 after.
The preferred ages from the Bee Pit, which range between 193 ± 21 ka and 210 ± 30 ka (MIS 6–7), were compared with the established glaciations in the Tatras, which in the published literature have been correlated and named according to the Alpine system (i.e. Mindel, Riss, Würm). The Bee Pit ages coincide primarily with deposits dated between 228 ± 44 ka and 263 ± 36 ka on the Polish side of the Tatras and correlated to the Riss glaciation according to Lindner
At the GYW in the Velická dolina valley, the oldest reliable (Section 6.2.3) age of 202 ± 22 ka is sampled in unit YN1 (sample 19096) and the youngest age of 139 ± 14 ka is sampled in unit YS3 (sample 19094). Sample 19096 was recovered from the hyperconcentrated flow deposit that suggests a high energy depositional environment most likely during the Riss I glaciation (MIS 6–7). On the one hand, the amount of suspended sediment in the meltwater increases in a colder climate due to the erosion caused by the glacier, supporting the interpretation of the deposition during a glacial period. On the other hand, such settings can also occur in transition phases from cold to warm periods that are typical of increased meltwater river discharge (e.g. Olszak
The moraine in the upper part of the Velická dolina valley (Site 8) was deposited during the last deglaciation, ∼15 ka ago, similar to that in other valleys in the Tatra Mountains (Engel
An abandoned gravel pit in the Biely Váh valley and several sites in the Velická dolina valley in the southern foothills of the High Tatra Mountains were dated by luminescence dating. The interpretations and discussion of the data allowed to draw the following conclusions.
The luminescence dating analysis for the 27 samples of the study area presented certain challenges. The OSL quartz analysis did not yield reliable results, even though several measurement alternatives were applied (standard SAR protocol, pulsed stimulation, differential OSL and LM-OSL). The conclusion was that quartz was contaminated with feldspar and thermally instable, and had a dim signal, a weak fast signal component and/or unstable signal component. Pulse annealing supports the assumption that quartz from the Tatra Mountains is unstable and that the OSL signal is influenced by thermal fading.
The signal of the feldspar displayed in general a brighter signal and presented a better option to determine the ages of our samples. Four ages were calculated for each sample using both IR50 and pIRIR225 signals, with and without correction for anomalous fading. The g-values for the pIRIR225 were relatively low (<1–3.3%/decade), and the uncorrected pIRIR225 ages were selected as the ages that estimate the most reliable time of deposition. These ages indicate that the sediments in the Biely váh and Velická dolina valleys were deposited during the later part of the Middle Pleistocene and the early Late Pleistocene. An exception is a moraine in the upper Velická dolina valley, which was dated to the last deglaciation (∼15 ka). However, for most of the samples, incomplete bleaching and high doses close to saturation lead to large uncertainties for the ages.
Given the nature of the sediments and complex transport history, it is recommended to attempt to sample the sediments further downstream in the Biely váh and Velická dolina valleys. A longer distance from the source could possibly provide a longer bleaching time for the sediments. Likewise, for further studies in the area, it is suggested to test other dating methods that would be less affected by the unfavourable luminescence characteristic of these sediments due to their depositional environment.