The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive character...The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.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 Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed rive...The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.展开更多
通过对黄河源区玛曲段河谷开展野外考察,在太吾若(TWR)发现典型的古洪水滞流沉积剖面。根据野外沉积学宏观特征判别,并结合粒度分布、磁化率、地球化学元素和石英颗粒微形态特征等室内实验分析测定结果,准确鉴别出TWR剖面所夹一组多层...通过对黄河源区玛曲段河谷开展野外考察,在太吾若(TWR)发现典型的古洪水滞流沉积剖面。根据野外沉积学宏观特征判别,并结合粒度分布、磁化率、地球化学元素和石英颗粒微形态特征等室内实验分析测定结果,准确鉴别出TWR剖面所夹一组多层洪水滞流沉积物(SWD),属典型的河流洪水在高水位滞流环境下沉积的悬移质泥沙。结果表明,TWR剖面古洪水SWD和现代洪水SWD沉积学分类为沙质粉沙,现代土壤为黏土质粉沙,现代风成沙为中沙。古洪水SWD粒度自然分布频率曲线为正偏,呈单峰,主峰高且峰值集中,分选性良好。古洪水SWD和现代洪水SWD磁化率较低,介于现代土壤和现代风成沙之间,化学元素明显区别于现代土壤和现代风成沙,表明它们尚未受到风化成壤作用影响,为古洪水悬移质快速沉积形成的滞流沉积物。石英颗粒微形态特征的分析表明,古洪水SWD和现代洪水SWD石英颗粒表面分布明显的三角痕、V形坑、撞击坑和凹面等水成沉积物的典型特征,属于河流沙类型。采用单片再生剂量法(SAR)光释光技术测年,证明在13.6~13.0 ka BP,黄河源地区经历了一期多次的大洪水事件,发生时段对应末次冰消期向全新世转折的时期,与欧洲和格陵兰冰芯记录末次冰消期中的Bolling/Aellrod暖期相对应,此时青藏高原地区冰川大规模消融,这期古洪水事件正是流域内冰融水大量下泄汇入黄河而形成的大洪水。展开更多
基金funded by the National Natural Science Foundation of China (Grants Nos. 41301012, 41771020 and U1405231)Natural Science Foundation of Fujian (Grant No. 2018R1034-5)Innovation Research Team Fund of Fujian Normal University (Grant No. IRTL1705)
文摘The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.
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。
基金supported by the National Natural Science Foundation of China(41977258)the China Geological Survey(DD20190310,DD20221761)the National Key R&D Program of China(2018YFC1504704).
文摘The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.
文摘通过对黄河源区玛曲段河谷开展野外考察,在太吾若(TWR)发现典型的古洪水滞流沉积剖面。根据野外沉积学宏观特征判别,并结合粒度分布、磁化率、地球化学元素和石英颗粒微形态特征等室内实验分析测定结果,准确鉴别出TWR剖面所夹一组多层洪水滞流沉积物(SWD),属典型的河流洪水在高水位滞流环境下沉积的悬移质泥沙。结果表明,TWR剖面古洪水SWD和现代洪水SWD沉积学分类为沙质粉沙,现代土壤为黏土质粉沙,现代风成沙为中沙。古洪水SWD粒度自然分布频率曲线为正偏,呈单峰,主峰高且峰值集中,分选性良好。古洪水SWD和现代洪水SWD磁化率较低,介于现代土壤和现代风成沙之间,化学元素明显区别于现代土壤和现代风成沙,表明它们尚未受到风化成壤作用影响,为古洪水悬移质快速沉积形成的滞流沉积物。石英颗粒微形态特征的分析表明,古洪水SWD和现代洪水SWD石英颗粒表面分布明显的三角痕、V形坑、撞击坑和凹面等水成沉积物的典型特征,属于河流沙类型。采用单片再生剂量法(SAR)光释光技术测年,证明在13.6~13.0 ka BP,黄河源地区经历了一期多次的大洪水事件,发生时段对应末次冰消期向全新世转折的时期,与欧洲和格陵兰冰芯记录末次冰消期中的Bolling/Aellrod暖期相对应,此时青藏高原地区冰川大规模消融,这期古洪水事件正是流域内冰融水大量下泄汇入黄河而形成的大洪水。
