Pub Date : 2018-01-01DOI: 10.1515/geochr-2015-0100
Kazumi Ito, T. Tamura, S. Tsukamoto
{"title":"Erratum: Post-IR IRSL dating of K-feldspar from last interglacial marine terrace deposits on the kamikita coastal plain, northeastern Japan","authors":"Kazumi Ito, T. Tamura, S. Tsukamoto","doi":"10.1515/geochr-2015-0100","DOIUrl":"https://doi.org/10.1515/geochr-2015-0100","url":null,"abstract":"","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66791482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-29DOI: 10.1515/geochr-2015-0081
K. Walshe
Abstract Koonalda Cave is located on the Nullarbor Plain of South Australia and is one of 17 deep karst caves in this region. In 2014, the cave was listed as a National Heritage Place in recognition of its significant archaeological and cultural heritage features. It In order to understand the antiquity of and complex human activity in this site a range of dating methods have been applied including typologic, radiometric and luminescence. Each has been challenged and the chronology of this highly significant site has relied on contextual data from other sites. This paper presents an overview of the archaeology recorded at Koonalda Cave, the issues in dating sites in deep karst systems and emphasises the urgent need to resolve these issues so that a reliable chronology can be presented for Koonalda Cave.
{"title":"Koonalda Cave, Nullarbor Plain, South Australia – issues in optical and radiometric dating of deep karst caves","authors":"K. Walshe","doi":"10.1515/geochr-2015-0081","DOIUrl":"https://doi.org/10.1515/geochr-2015-0081","url":null,"abstract":"Abstract Koonalda Cave is located on the Nullarbor Plain of South Australia and is one of 17 deep karst caves in this region. In 2014, the cave was listed as a National Heritage Place in recognition of its significant archaeological and cultural heritage features. It In order to understand the antiquity of and complex human activity in this site a range of dating methods have been applied including typologic, radiometric and luminescence. Each has been challenged and the chronology of this highly significant site has relied on contextual data from other sites. This paper presents an overview of the archaeology recorded at Koonalda Cave, the issues in dating sites in deep karst systems and emphasises the urgent need to resolve these issues so that a reliable chronology can be presented for Koonalda Cave.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45478233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-29DOI: 10.1515/geochr-2015-0076
T. Tamura, Kazumi Ito, Takahiko Inoue, T. Sakai
Abstract We applied infrared stimulated luminescence (IRSL50) and post-infrared (post-IR) IRSL150 dating to K-feldspar sand obtained from Holocene beach ridges on the Yumigahama Peninsula, Japan, to investigate the rate of progradation of the beach, which has been affected by 17–18th century iron mining in a local river catchment. All samples showed higher equivalent doses for the post-IR IRSL signal. Fading tests indicated that IRSL yielded relatively high g-values (11–13%/decade), while post-IR IRSL yielded negative g-values (–5 to –8%/decade). The corrected IRSL age of the oldest sample, 8.1 ± 1.3 ka, was slightly overestimated with respect to its expected age of 5–6.7 ka. The corrected age is highly dependent on the g-value, which if slightly inaccurate would have caused the overestimate. The uncorrected post-IR IRSL ages were underestimated, and we consider that the post-IR IRSL signal faded. However, given the negative g-values, application of an appropriate fading correction was not feasible. The corrected IRSL ages of the younger samples, coupled with an assumption of residual dose, roughly agreed with the historical shoreline changes, indicating that the rate of shoreline progradation increased markedly during the recent period of mining-related enhanced sediment discharge.
{"title":"Luminescence dating of Holocene beach-ridge sands on the Yumigahama Peninsula, western Japan","authors":"T. Tamura, Kazumi Ito, Takahiko Inoue, T. Sakai","doi":"10.1515/geochr-2015-0076","DOIUrl":"https://doi.org/10.1515/geochr-2015-0076","url":null,"abstract":"Abstract We applied infrared stimulated luminescence (IRSL50) and post-infrared (post-IR) IRSL150 dating to K-feldspar sand obtained from Holocene beach ridges on the Yumigahama Peninsula, Japan, to investigate the rate of progradation of the beach, which has been affected by 17–18th century iron mining in a local river catchment. All samples showed higher equivalent doses for the post-IR IRSL signal. Fading tests indicated that IRSL yielded relatively high g-values (11–13%/decade), while post-IR IRSL yielded negative g-values (–5 to –8%/decade). The corrected IRSL age of the oldest sample, 8.1 ± 1.3 ka, was slightly overestimated with respect to its expected age of 5–6.7 ka. The corrected age is highly dependent on the g-value, which if slightly inaccurate would have caused the overestimate. The uncorrected post-IR IRSL ages were underestimated, and we consider that the post-IR IRSL signal faded. However, given the negative g-values, application of an appropriate fading correction was not feasible. The corrected IRSL ages of the younger samples, coupled with an assumption of residual dose, roughly agreed with the historical shoreline changes, indicating that the rate of shoreline progradation increased markedly during the recent period of mining-related enhanced sediment discharge.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46901035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-29DOI: 10.1515/geochr-2015-0077
Kazumi Ito, T. Tamura, S. Tsukamoto
Abstract To establish a suitable luminescence dating protocol for marine terrace deposits in Japan, we tested the applicability of K-feldspar post-infrared (IR) infrared stimulated luminescence (IRSL) (pIRIR) dating using a marine isotope stage (MIS) 5e terrace deposit from the Kamikita coastal plain (NE Japan), where independent age control from a tephra is available. One of the most commonly used pIRIR signals, measured at 290°C with the first IR stimulation temperature at 50°C (pIRIR50/290), faded with a mean g2days value of 1.94 ± 0.19%/decade. In contrast, the pIRIR signal with a higher first IR stimulation temperature of 200°C (pIRIR200/290) had a much lower fading rate (g2days = 0.16 ± 0.49%/decade). The average fading-uncorrected and -corrected pIRIR200/290 ages of MIS 5e subtidal sediments obtained from two sampling sites were 126 ± 3 ka and 132 ± 2 ka, which is in good agreement with the independent age control. We conclude that is it is now possible to use pIRIR protocol to estimate the ages of not only marine terraces formed during MIS 5 substages (5a, 5c) but also of older marine terraces, for which age evidence is limited.
{"title":"Post-IR IRSL dating of K-feldspar from last interglacial marine terrace deposits on the Kamikita coastal plain, northeastern Japan","authors":"Kazumi Ito, T. Tamura, S. Tsukamoto","doi":"10.1515/geochr-2015-0077","DOIUrl":"https://doi.org/10.1515/geochr-2015-0077","url":null,"abstract":"Abstract To establish a suitable luminescence dating protocol for marine terrace deposits in Japan, we tested the applicability of K-feldspar post-infrared (IR) infrared stimulated luminescence (IRSL) (pIRIR) dating using a marine isotope stage (MIS) 5e terrace deposit from the Kamikita coastal plain (NE Japan), where independent age control from a tephra is available. One of the most commonly used pIRIR signals, measured at 290°C with the first IR stimulation temperature at 50°C (pIRIR50/290), faded with a mean g2days value of 1.94 ± 0.19%/decade. In contrast, the pIRIR signal with a higher first IR stimulation temperature of 200°C (pIRIR200/290) had a much lower fading rate (g2days = 0.16 ± 0.49%/decade). The average fading-uncorrected and -corrected pIRIR200/290 ages of MIS 5e subtidal sediments obtained from two sampling sites were 126 ± 3 ka and 132 ± 2 ka, which is in good agreement with the independent age control. We conclude that is it is now possible to use pIRIR protocol to estimate the ages of not only marine terraces formed during MIS 5 substages (5a, 5c) but also of older marine terraces, for which age evidence is limited.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0077","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48995982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-29DOI: 10.1515/geochr-2015-0072
L. Panzeri, M. Cantù, M. Martini, E. Sibilia
Abstract In this study, OSL dating was applied to earthen mortars, consisting in a quartz-rich aggregate dispersed in silty-clayey matrix. The samples were taken from two independently dated structures in Cremona, Northern Italy (Palazzo Raimondi, 1495–1499 AD and Palazzo Soldi, 1770–1790 AD). The evaluation of the equivalent dose (De) was attempted with both the multigrain and the single grain protocols using the 150–250 μm quartz fraction. The reliability and effectiveness of the various statistical methods in identifying the well-bleached samples were tested. The use of the multi-grain technique gave unreliable results, due to the high amount of poorly bleached grains. With the single-grain technique, more promising results were obtained: in particular, the un-log MAM3 and IEU models allowed an accurate evaluation of the mortar expected age in most cases, even if the precision is still relatively low.
{"title":"Application of different protocols and age-models in OSL dating of earthen mortars","authors":"L. Panzeri, M. Cantù, M. Martini, E. Sibilia","doi":"10.1515/geochr-2015-0072","DOIUrl":"https://doi.org/10.1515/geochr-2015-0072","url":null,"abstract":"Abstract In this study, OSL dating was applied to earthen mortars, consisting in a quartz-rich aggregate dispersed in silty-clayey matrix. The samples were taken from two independently dated structures in Cremona, Northern Italy (Palazzo Raimondi, 1495–1499 AD and Palazzo Soldi, 1770–1790 AD). The evaluation of the equivalent dose (De) was attempted with both the multigrain and the single grain protocols using the 150–250 μm quartz fraction. The reliability and effectiveness of the various statistical methods in identifying the well-bleached samples were tested. The use of the multi-grain technique gave unreliable results, due to the high amount of poorly bleached grains. With the single-grain technique, more promising results were obtained: in particular, the un-log MAM3 and IEU models allowed an accurate evaluation of the mortar expected age in most cases, even if the precision is still relatively low.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49235754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-29DOI: 10.1515/geochr-2015-0079
O. Tóth, G. Sipos, T. Kiss, Tamás Bartyik
Abstract Reliable OSL dating of fluvial sediments requires an assessment of incomplete bleaching and consequent residual dose in samples. A well-established way of this is determining the equivalent dose of modern samples from similar sedimentary environments as in the case of palaeo-samples. Meanwhile, relatively low, or close to zero doses are also greatly affected by the thermal transfer phenomenon, which can also lead to a palaeodose overestimation. The present study attempts to quantify both factors in coarse and fine grain modern sediments along the Hungarian section of the Danube River, with the aim of determining their significance when dating both young and palaeo-sediments. Investigations were performed at 30 sites along a 417 km long river section with varying morphological and erosive character. The studied samples were deposited during the record flood of 2013, mobilising and relocating a vast amount of sediment in the system. Tests have shown that thermal transfer can be minimized successfully by choosing preheat temperatures below 200°C, however it remains a significant factor when dating young or modern sediments. Based on equivalent dose measurements, coarse grain samples proved to be relatively well bleached, and residual doses showed only a minor spatial variation. Although in terms of fine grain samples residual doses were obviously much higher, results can enhance the reliability of dates retrieved later from fine grain palaeo-samples. In the meantime, the higher spatial variability of fine grain residual doses may also allow the assessment of the erosive character of different river reaches.
{"title":"Variation of OSL residual doses in terms of coarse and fine grain modern sediments along the Hungarian section of the Danube","authors":"O. Tóth, G. Sipos, T. Kiss, Tamás Bartyik","doi":"10.1515/geochr-2015-0079","DOIUrl":"https://doi.org/10.1515/geochr-2015-0079","url":null,"abstract":"Abstract Reliable OSL dating of fluvial sediments requires an assessment of incomplete bleaching and consequent residual dose in samples. A well-established way of this is determining the equivalent dose of modern samples from similar sedimentary environments as in the case of palaeo-samples. Meanwhile, relatively low, or close to zero doses are also greatly affected by the thermal transfer phenomenon, which can also lead to a palaeodose overestimation. The present study attempts to quantify both factors in coarse and fine grain modern sediments along the Hungarian section of the Danube River, with the aim of determining their significance when dating both young and palaeo-sediments. Investigations were performed at 30 sites along a 417 km long river section with varying morphological and erosive character. The studied samples were deposited during the record flood of 2013, mobilising and relocating a vast amount of sediment in the system. Tests have shown that thermal transfer can be minimized successfully by choosing preheat temperatures below 200°C, however it remains a significant factor when dating young or modern sediments. Based on equivalent dose measurements, coarse grain samples proved to be relatively well bleached, and residual doses showed only a minor spatial variation. Although in terms of fine grain samples residual doses were obviously much higher, results can enhance the reliability of dates retrieved later from fine grain palaeo-samples. In the meantime, the higher spatial variability of fine grain residual doses may also allow the assessment of the erosive character of different river reaches.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48068837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-30DOI: 10.1515/geochr-2015-0074
P. Moska, G. Adamiec, Z. Jary, A. Bluszcz
Abstract The presented work concerns a loess profile located in Tyszowce, in the eastern part of Poland on the Volyn Upland, close to the Ukrainian border. The investigated loess formation is well preserved and is characterised by clear stratigraphic units providing an opportunity to refine the loess chronostratigraphy in Poland. In the paper, we present luminescence ages of loess from the last glacial cycle in SE Poland (up to about 100 ka) together with seven radiocarbon ages. Twenty-one samples were collected and dated using infrared (post-IR IRSL) and blue light stimulated luminescence dating. Two fractions were used, namely polymineral fine grains (4–11 μm) and medium sized quartz grains (45–63 μm). The obtained luminescence ages show very good agreement of both methods in relation to loess deposits, however for the fossil soil units the post-IR IRSL method yields older ages. Radiocarbon dates also confirm luminescence chronostratigraphy for younger units. Moreover, the luminescence results are supported by detailed analyses of grain size distribution, carbonate content and magnetic susceptibility variations allowing to create a comprehensive picture of chronological evolution of this site.
{"title":"OSL chronostratigraphy for loess deposits from Tyszowce – Poland","authors":"P. Moska, G. Adamiec, Z. Jary, A. Bluszcz","doi":"10.1515/geochr-2015-0074","DOIUrl":"https://doi.org/10.1515/geochr-2015-0074","url":null,"abstract":"Abstract The presented work concerns a loess profile located in Tyszowce, in the eastern part of Poland on the Volyn Upland, close to the Ukrainian border. The investigated loess formation is well preserved and is characterised by clear stratigraphic units providing an opportunity to refine the loess chronostratigraphy in Poland. In the paper, we present luminescence ages of loess from the last glacial cycle in SE Poland (up to about 100 ka) together with seven radiocarbon ages. Twenty-one samples were collected and dated using infrared (post-IR IRSL) and blue light stimulated luminescence dating. Two fractions were used, namely polymineral fine grains (4–11 μm) and medium sized quartz grains (45–63 μm). The obtained luminescence ages show very good agreement of both methods in relation to loess deposits, however for the fossil soil units the post-IR IRSL method yields older ages. Radiocarbon dates also confirm luminescence chronostratigraphy for younger units. Moreover, the luminescence results are supported by detailed analyses of grain size distribution, carbonate content and magnetic susceptibility variations allowing to create a comprehensive picture of chronological evolution of this site.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42949592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-23DOI: 10.1515/geochr-2015-0078
D. Koul, A. Soni, D. Datta
Abstract In this study, some novel features of the post 500°C blue stimulated optically stimulated luminescence (OSL) of fired geological quartz are reported. Different observations (i) pulse annealing and (ii) impact of bleaching on high temperature TL glow peak suggested 510°C (heating rate of 2°C/s) TL peak trap to be responsible for the observed emission. The dosimetric properties of this emission were seen to make its applicability for dose assessment till kGy range. The signal was seen to be easily bleachable, reaching background value within 100 s with blue light at 125°C. The signal qualified all the tests (i) reproducibility, (ii) negligible recuperation and (iii) accuracy of dose recovery needed for reliable assessment of the radiation dose with modified Single aliquot regenerative (SAR) protocol. Considering the bleachability and high dynamic dose range of this signal, it has the potential to stretch the upper dose limit of dating by one order of magnitude than possible with conventional OSL, corresponding to 325°C TL trap. So, combining all the results, the signal reported here could be very useful for dosimetric applications involving measurement of high radiation dose, like dating.
{"title":"Some novel features of post-500°C heating blue stimulated OSL emission of fired natural quartz","authors":"D. Koul, A. Soni, D. Datta","doi":"10.1515/geochr-2015-0078","DOIUrl":"https://doi.org/10.1515/geochr-2015-0078","url":null,"abstract":"Abstract In this study, some novel features of the post 500°C blue stimulated optically stimulated luminescence (OSL) of fired geological quartz are reported. Different observations (i) pulse annealing and (ii) impact of bleaching on high temperature TL glow peak suggested 510°C (heating rate of 2°C/s) TL peak trap to be responsible for the observed emission. The dosimetric properties of this emission were seen to make its applicability for dose assessment till kGy range. The signal was seen to be easily bleachable, reaching background value within 100 s with blue light at 125°C. The signal qualified all the tests (i) reproducibility, (ii) negligible recuperation and (iii) accuracy of dose recovery needed for reliable assessment of the radiation dose with modified Single aliquot regenerative (SAR) protocol. Considering the bleachability and high dynamic dose range of this signal, it has the potential to stretch the upper dose limit of dating by one order of magnitude than possible with conventional OSL, corresponding to 325°C TL trap. So, combining all the results, the signal reported here could be very useful for dosimetric applications involving measurement of high radiation dose, like dating.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0078","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43881896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-23DOI: 10.1515/geochr-2015-0075
Huili Yang, Jie Chen, N. Porat, Tao Li, Wenqiao Li, Weipeng Xiao
Abstract Optical dating of earthquake related sediments were investigated including one modern sample and three samples from a trench excavated across the 1985 Ms7.4 Wuqia Earthquake surface rupture. The results indicated that equivalent dose (De) values vary with grain size and the method used for De determination. The residual dose of the modern sample is 0.1 ka ( 0.2−0.1+0.2 $begin{array}{} 0.2_{-0.1}^{+0.2} end{array} $ Gy) for the quartz single grain measurements. Only 1.5–3.6% of the grains have a detectable OSL signal. Single grain quartz ages are similar to the expected ages. Fine grain quartz results overestimate the De values and are much older than single grain quartz and coarse grain quartz small aliquot standardized growth curve (SA-SGC) ages. Single grain quartz OSL dating may be optimal for dating earthquake related deposits, but SA-SGC can save measurement time and has potential for dating some poorly bleaching samples.
{"title":"Coarse versus fine-grain quartz optical dating of the sediments related to the 1985 Ms7.1 Wuqia earthquake, northeastern margin of the Pamir salient, China","authors":"Huili Yang, Jie Chen, N. Porat, Tao Li, Wenqiao Li, Weipeng Xiao","doi":"10.1515/geochr-2015-0075","DOIUrl":"https://doi.org/10.1515/geochr-2015-0075","url":null,"abstract":"Abstract Optical dating of earthquake related sediments were investigated including one modern sample and three samples from a trench excavated across the 1985 Ms7.4 Wuqia Earthquake surface rupture. The results indicated that equivalent dose (De) values vary with grain size and the method used for De determination. The residual dose of the modern sample is 0.1 ka ( 0.2−0.1+0.2 $begin{array}{} 0.2_{-0.1}^{+0.2} end{array} $ Gy) for the quartz single grain measurements. Only 1.5–3.6% of the grains have a detectable OSL signal. Single grain quartz ages are similar to the expected ages. Fine grain quartz results overestimate the De values and are much older than single grain quartz and coarse grain quartz small aliquot standardized growth curve (SA-SGC) ages. Single grain quartz OSL dating may be optimal for dating earthquake related deposits, but SA-SGC can save measurement time and has potential for dating some poorly bleaching samples.","PeriodicalId":50421,"journal":{"name":"Geochronometria","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2017-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/geochr-2015-0075","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49505871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-16DOI: 10.1515/geochr-2015-0061
A. E. Harsini, S. A. Mazaheri, S. Saadat, J. Santos
Abstract This paper addresses U-Pb geochronology, Sr-Nd geochemistry, petrogenesis and tectonic setting in the Gandab volcanic rocks. The Gandab volcanic rocks belong to the Sabzevar zone magmatic arc (northeastern Iran). Petrographically, all the studied volcanic rocks indicate porphyritic textures with phenocrysts of plagioclase, K-feldespar, hornblende, pyroxene, and magnetite which are embedded in a fine to medium grained groundmass. As well, amygdaloidal, and poikilitic textures are seen in some rocks. The standard chemical classifications show that the studied rocks are basaltic trachy andesite, trachy andesite, trachyte, and trachy dacite. Major elements reveal that the studied samples are metaluminous and their alumina saturation index varies from 0.71 to 1.02. The chondrite-normalized rare earth element and mantle-normalized trace element patterns show enrichment in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and in large ion lithophile elements (LILE) relative to high field strength elements (HFSE). As well they show a slightly negative Eu anomaly (Eu/Eu* = 0.72 – 0.97). The whole-rock geochemistry of the studied rocks suggests that they are related to each other by fractional crystallization. LA-MC-ICP-MS U-Pb analyses in zircon grains from two volcanic rock samples (GCH-119 and GCH-171) gave ages ranging of 5.47 ± 0.22 Ma to 2.44 ± 0.79 Ma, which corresponds to the Pliocene period. In four samples analysed for Sr and Nd isotopes 87Sr/86Sr ratios range from 0.704082 to 0.705931 and εNd values vary between +3.34 and +5. These values could be regarded to as representing mantle derived magmas. Taking into account the comparing rare earth element (REE) patterns, an origin of the parental magmas in enriched lithospheric mantle is suggested. Finally, it is concluded that Pliocene Gandab volcanic rocks are related to the post-collision environment that followed the Neo-Tethys subduction.
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