The timing of Palaeolithic human activities in South China is still controversial because of the lack of a reliable chronology of archaeological sites.The Longdengshan Palaeolithic site(LPS),located close to the Wuyi ...The timing of Palaeolithic human activities in South China is still controversial because of the lack of a reliable chronology of archaeological sites.The Longdengshan Palaeolithic site(LPS),located close to the Wuyi Mountain of South China,represents the first discovered and scientifically excavated Middle Palaeolithic site in the Fujian Province.This site is of considerable significance for studying the diffusion and cultural connotation of early Homo sapiens in southern China.In this study,we present optically stimulated luminescence(OSL)ages obtained from medium-grained quartz collected at the LPS.The single-aliquot regenerative-dose measurements of red soil deposits collected at the same site yielded internally and stratigraphically consistent ages and similar errors,indicating a potential ability of the technique,and also reflecting the influence of various sedimentary facies on the test results.Our results indicate that the 38–63µm quartz grains were generally partially-bleached and had large values of over-dispersion in the palaeo-reticulated laterites of west Fujian.Some samples yielded unsatisfactory results,suggesting that the degree of bleaching of diluvial and alluvial deposits should be properly assessed before dating.We did not detect any enrichment/depletion of U,Th and radioactive disequilibrium.The effect of chemical weathering on the dose rate estimation was negligible.Therefore,we used a central age model and the maximum age model to calculate the age of two samples,respectively,and the minimum age model to calculate the ages of the rest of the samples.The OSL ages of the samples ranged from 27.09±2.30 ka to 54.65±7.39 ka for the 38–63µm quartz size fraction,and roughly corresponded to the Marine Isotope Stage 3.In addition,three ages out of five are based on the calculation of minimum ages in this research,which needs to be further verified by other dating methods.展开更多
Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the cli...Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the climate ameliorated and the Monsoon rains reappeared,ice-wedges developed.Further warming permitted thawing of the ice infillings accompanied by replacement of the ice by sediments partly from the host ground as well as from the surface by wind or sheet wash.In cases of extreme surface water flow on slopes after 10 ka B.P.,small baydjarakhs typically c.50 cm high developed,only to have the resulting hollows infilled by sediments carried by wind and/or sheet wash.These shallow structures form a network on top of many of the cryogenic wedges.This complex history makes dating the ages of the wedges difficult using OSL methodology.Unfortunately,past field work ignored the problem of the angle of the cut face to the direction of the wedge infilling when sampling the contents of the narrow wedges,resulting in potential contamination of the samples with the host sediment.Sampling of the larger deposits should be alright,but the likelihood of contamination makes the interpretation of the resulting OSL dates from the narrow wedges questionable.Primary wedges consisting of primary mineral infillings should still have similar OSL dates with depth for a given wedge,but the distinction between ice-wedge infillings and soil wedges is difficult since both can exhibit older dates of the infillings with depth.The available data suggests that ice-wedges were significantly more common than sediment-filled primary wedges.A protocol to avoid having to obtain large numbers of OSL dates by more careful field sampling and the use of grain size determinations is provided in the Appendix.展开更多
河流阶地是研究河流演化、构造运动的良好载体,虽然北京地区第四纪地质研究程度较高,但北京东部地区对河流阶地的相关研究资料较少。笔者等以北京平谷燕山山前发育的泃河、黄松峪石河、将军关石河为研究对象,通过野外地质调查、光释光...河流阶地是研究河流演化、构造运动的良好载体,虽然北京地区第四纪地质研究程度较高,但北京东部地区对河流阶地的相关研究资料较少。笔者等以北京平谷燕山山前发育的泃河、黄松峪石河、将军关石河为研究对象,通过野外地质调查、光释光测年技术(OSL)详细划分了上述河流阶地的发育序列,在此基础上讨论了部分河流阶地的形成时代、阶地成因及河流阶地对燕山隆升的响应等地质问题,认为泃河南岸发育有3级阶地,北岸发育2级阶地;黄松峪石河最多发育有6级阶地;将军关石河发育有5级阶地。将军关石河至晚形成于中更新世晚期(161.7±7.7 ka BP),黄松峪石河至晚形成于晚更新世早期(121.2±5.4~100.3±4.1 ka BP),泃河至晚形成于晚更新世中期(79.4±3.3~70.8±3.4 ka BP)。泃河、黄松峪石河、将军关石河各级阶地的形成受到了古气候变化和燕山隆升的双重影响,平谷地区燕山在中更新世晚期以来,一直处于隆升的状态,晚更新世早期时隆升速率达到最大,可达0.24~0.34 mm/a,晚更新世中期时隆升速率降低,0.18~0.24 mm/a。以上成果对研究北京东部河流阶地发育特征、形成时代具有重要参考价值,也为中更新世晚期以来燕山的隆升提供了新的证据。展开更多
The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and...The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and the GemişFault Zone(GFZ)to the southeast that have triggered significant earthquakes,causing considerable damage.This study focuses on the Bozkurt segment of the MF,which caused a damaging earthquake(Mw 6.0)in 2019 and another significant earthquake in 1886 during historical times.A paleoseismological trench survey along the Bozkurt segment revealed at least two faulting events,with the last event producing a vertical displacement of 0.25 m.The Optical Stimulated Luminescence(OSL)dating indicates that the last earthquake occurred 3.13±0.33 ka BP,while the penultimate earthquake occurred 4.0±0.72 ka BP.These dates correspond to a long-term slip rate of approximately 0.36±0.11 mm/a and a mean recurrence interval of 2.08 ka,short-term slip rate 0.78±0.16 mm/a and recurrence interval of 0.96 ka,and compatible with the mean sedimentation rate of 0.26 mm/a,calculated from drill logs in Acıgöl basin-fill.Considering the 6 km length of the Bozkurt segment and its vertical displacement of 0.25 m in the last event,this segment has the potential to generate earthquakes ranging from 5.6 to 5.9 Mw.Long-term slip rates derived from geomorphological data are 0.56 mm/year to the north and 0.64 mm/a to the south of the graben,indicating higher subsidence on the southern margin.These rates are in accordance with the slip rates calculated from the paleoseismological trench survey and sedimentation rate from the drill-log.These indications show that the Bozkurt segment is an active Holocene fault with relatively long recurrence intervals and low-slip rate.Consequently,the paleoseismological studies in combination with geomorphological data are important tool to assess seismic hazards and to define the characteristics of individual fault segments.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.41301012,42077407 and 41771020),Natural Science Foundation of Fujian Province,China(Grant No.2020J01185),and the Innovation Research Team Fund of Fujian Normal University(Grant No.IRTL1705).
文摘The timing of Palaeolithic human activities in South China is still controversial because of the lack of a reliable chronology of archaeological sites.The Longdengshan Palaeolithic site(LPS),located close to the Wuyi Mountain of South China,represents the first discovered and scientifically excavated Middle Palaeolithic site in the Fujian Province.This site is of considerable significance for studying the diffusion and cultural connotation of early Homo sapiens in southern China.In this study,we present optically stimulated luminescence(OSL)ages obtained from medium-grained quartz collected at the LPS.The single-aliquot regenerative-dose measurements of red soil deposits collected at the same site yielded internally and stratigraphically consistent ages and similar errors,indicating a potential ability of the technique,and also reflecting the influence of various sedimentary facies on the test results.Our results indicate that the 38–63µm quartz grains were generally partially-bleached and had large values of over-dispersion in the palaeo-reticulated laterites of west Fujian.Some samples yielded unsatisfactory results,suggesting that the degree of bleaching of diluvial and alluvial deposits should be properly assessed before dating.We did not detect any enrichment/depletion of U,Th and radioactive disequilibrium.The effect of chemical weathering on the dose rate estimation was negligible.Therefore,we used a central age model and the maximum age model to calculate the age of two samples,respectively,and the minimum age model to calculate the ages of the rest of the samples.The OSL ages of the samples ranged from 27.09±2.30 ka to 54.65±7.39 ka for the 38–63µm quartz size fraction,and roughly corresponded to the Marine Isotope Stage 3.In addition,three ages out of five are based on the calculation of minimum ages in this research,which needs to be further verified by other dating methods.
文摘Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the climate ameliorated and the Monsoon rains reappeared,ice-wedges developed.Further warming permitted thawing of the ice infillings accompanied by replacement of the ice by sediments partly from the host ground as well as from the surface by wind or sheet wash.In cases of extreme surface water flow on slopes after 10 ka B.P.,small baydjarakhs typically c.50 cm high developed,only to have the resulting hollows infilled by sediments carried by wind and/or sheet wash.These shallow structures form a network on top of many of the cryogenic wedges.This complex history makes dating the ages of the wedges difficult using OSL methodology.Unfortunately,past field work ignored the problem of the angle of the cut face to the direction of the wedge infilling when sampling the contents of the narrow wedges,resulting in potential contamination of the samples with the host sediment.Sampling of the larger deposits should be alright,but the likelihood of contamination makes the interpretation of the resulting OSL dates from the narrow wedges questionable.Primary wedges consisting of primary mineral infillings should still have similar OSL dates with depth for a given wedge,but the distinction between ice-wedge infillings and soil wedges is difficult since both can exhibit older dates of the infillings with depth.The available data suggests that ice-wedges were significantly more common than sediment-filled primary wedges.A protocol to avoid having to obtain large numbers of OSL dates by more careful field sampling and the use of grain size determinations is provided in the Appendix.
文摘河流阶地是研究河流演化、构造运动的良好载体,虽然北京地区第四纪地质研究程度较高,但北京东部地区对河流阶地的相关研究资料较少。笔者等以北京平谷燕山山前发育的泃河、黄松峪石河、将军关石河为研究对象,通过野外地质调查、光释光测年技术(OSL)详细划分了上述河流阶地的发育序列,在此基础上讨论了部分河流阶地的形成时代、阶地成因及河流阶地对燕山隆升的响应等地质问题,认为泃河南岸发育有3级阶地,北岸发育2级阶地;黄松峪石河最多发育有6级阶地;将军关石河发育有5级阶地。将军关石河至晚形成于中更新世晚期(161.7±7.7 ka BP),黄松峪石河至晚形成于晚更新世早期(121.2±5.4~100.3±4.1 ka BP),泃河至晚形成于晚更新世中期(79.4±3.3~70.8±3.4 ka BP)。泃河、黄松峪石河、将军关石河各级阶地的形成受到了古气候变化和燕山隆升的双重影响,平谷地区燕山在中更新世晚期以来,一直处于隆升的状态,晚更新世早期时隆升速率达到最大,可达0.24~0.34 mm/a,晚更新世中期时隆升速率降低,0.18~0.24 mm/a。以上成果对研究北京东部河流阶地发育特征、形成时代具有重要参考价值,也为中更新世晚期以来燕山的隆升提供了新的证据。
文摘The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and the GemişFault Zone(GFZ)to the southeast that have triggered significant earthquakes,causing considerable damage.This study focuses on the Bozkurt segment of the MF,which caused a damaging earthquake(Mw 6.0)in 2019 and another significant earthquake in 1886 during historical times.A paleoseismological trench survey along the Bozkurt segment revealed at least two faulting events,with the last event producing a vertical displacement of 0.25 m.The Optical Stimulated Luminescence(OSL)dating indicates that the last earthquake occurred 3.13±0.33 ka BP,while the penultimate earthquake occurred 4.0±0.72 ka BP.These dates correspond to a long-term slip rate of approximately 0.36±0.11 mm/a and a mean recurrence interval of 2.08 ka,short-term slip rate 0.78±0.16 mm/a and recurrence interval of 0.96 ka,and compatible with the mean sedimentation rate of 0.26 mm/a,calculated from drill logs in Acıgöl basin-fill.Considering the 6 km length of the Bozkurt segment and its vertical displacement of 0.25 m in the last event,this segment has the potential to generate earthquakes ranging from 5.6 to 5.9 Mw.Long-term slip rates derived from geomorphological data are 0.56 mm/year to the north and 0.64 mm/a to the south of the graben,indicating higher subsidence on the southern margin.These rates are in accordance with the slip rates calculated from the paleoseismological trench survey and sedimentation rate from the drill-log.These indications show that the Bozkurt segment is an active Holocene fault with relatively long recurrence intervals and low-slip rate.Consequently,the paleoseismological studies in combination with geomorphological data are important tool to assess seismic hazards and to define the characteristics of individual fault segments.
