一、国内外全新世研究概略全新世是地质历史最新的一页,与人类活动的关系极为密切,因此人们对其研究更为重视。有关全新世地层的划分,普遍采用所谓布列特-色尔南德尔方案,把全新世划分为五个气候期,自老至新为: 亚北极期(或称前北方期)...一、国内外全新世研究概略全新世是地质历史最新的一页,与人类活动的关系极为密切,因此人们对其研究更为重视。有关全新世地层的划分,普遍采用所谓布列特-色尔南德尔方案,把全新世划分为五个气候期,自老至新为: 亚北极期(或称前北方期):寒冷;北方期:干而温;大西洋期:湿而暖;亚北方期:干而温;亚大西洋期:湿而凉。波斯特(L. V. Post,1944)研究南波罗的海泥炭沼泽的孢粉.展开更多
Based on the stratigraphic sequence formed since the last glaciation and revealed by 3000 km long high-resolution shallow seismic profiles and the core QDZ03 acquired recently off the southern Shandong Peninsula, we a...Based on the stratigraphic sequence formed since the last glaciation and revealed by 3000 km long high-resolution shallow seismic profiles and the core QDZ03 acquired recently off the southern Shandong Peninsula, we addressed the sedimentary characteristics of a Holocene subaqueous clinoform in this paper. Integrated analyses were made on the core QDZ03, including sedimentary facies, sediment grain sizes, clay minerals, geochemistry, micro paleontology, and AMS 14 C dating. The result indicates that there exists a Holocene subaqueous clinoform, whose bottom boundary generally lies at 15–40 m below the present sea level with its depth contours roughly parallel to the coast and getting deeper seawards. The maximum thickness of the clinoform is up to 22.5 m on the coast side, and the thickness contours generally spread in a banded way along the coastline and becomes thinner towards the sea. At the mouths of some bays along the coast, the clinoform stretches in the shape of a fan and its thickness is evidently larger than that of the surrounding sediments. This clinoform came into being in the early Holocene(about 11.2 cal kyr BP) and can be divided into the lower and upper depositional units(DU 2 and DU 1, respectively). The unit DU 2, being usually less than 3 m in thickness and formed under a low sedimentation rate, is located between the bottom boundary and the Holocene maximum flooding surface(MFS), and represents the sediment of a post-glacial transgressive systems tract; whereas the unit DU 1, the main body of the clinoform, sits on the MFS, belonging to the sediment of a highstand systems tract from middle Holocene(about 7–6 cal kyr BP) to the present. The provenance of the clinoform differs from that of the typical sediments of the Yellow River and can be considered as the results of the joint contribution from both the Yellow River and the proximal coastal sediments of the Shandong Peninsula, as evidenced by the sediment geochemistry of the core. As is controlled mainly by coactions of multiple factors such as the Holocene sea-level changes, sediment supplies and coastal dynamic conditions, the development of the clinoform is genetically related with the synchronous clinoform or subaqueous deltas around the northeastern Shandong Peninsula and in the northern South Yellow Sea in the spatial distribution and sediment provenance, as previously reported, with all of them being formed from the initial stage of the Holocene up to the present.展开更多
Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial ...Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial Period. The results cover the late Last Deglacial Period and the Holocene. The climate was very unstable and rather arid during the late Last Deglacial Period. The Holocene can be divided into three periods： the early Holocene （11360-8240 cal aB. P. ）, which was dry but unstable and featured rising temperatures, the mid-Holocene （8240-3200 cal aB. P. ）, which was warm and wet and the late Holocene （ since 3200 cal aBP）, which was cold and dry. Results also show a warm-wet event around 1500 cal aB. P.展开更多
The Longling-Ruili fault is an important active fault in Southwestern China, striking generally northeast. The fault controls the development of the sedimentary series and magmatic action on its two sides, as well as ...The Longling-Ruili fault is an important active fault in Southwestern China, striking generally northeast. The fault controls the development of the sedimentary series and magmatic action on its two sides, as well as the development of the Longling basin, Mangshi basin and the Zhefang basin along it. Due to limited Quaternary sediments and harsh natural conditions, the study of late Quaternary fault activity on the northern segment of the Longling-Ruili fault is lacking and the time of the newest faulting and the Quaternary slip rate are not clear at present. Based on the interpretation of remote images, quantitative geomorphologic deformation measurements and dating of young terrace deposits and alluvial fans, this paper obtains some new results as follows. The northern segment of the Longling-Ruili fault is a Holocene dextral strike-slip fault with some component of a normal slip. The terrace T1 composing mainly of alluvial deposits formed during 4ka B. P. was offset by the northern segment of the Longling-Ruili fault and its left-lateral and its vertical displacements are 8m - 12m and 2m, respectively. The late Pleistocene alluvial fan was displaced with a left-lateral and vertical displacement of 70m and lgm, respectively. The strike-slip rate of the Longling-Ruili fault is 2.2mm/a 2.5mm/a and the vertical slip rate is 0.6mm/a since the late Pleistocene epoch. The strike-slip rate of the Longling-Ruili fault is 1.8mm/a - 3.0mm/a and vertical slip rate is 0.5mm/a during the Holocene epoch. The proportion of horizontal to vertical displacement is about 4： 1, which means that the vertical slip rate on the northern segment of the Longling-Ruili fault is about 25 % of the horizontal slip rate. The left-lateral slip rate in the late Holocene is consistent with the GPS measurement. The strike slip rate is of great consistency in different time scales since the late Pleistocene epoch, indicating that the activity of the Longling-Ruili fault is of great stability.展开更多
文摘一、国内外全新世研究概略全新世是地质历史最新的一页,与人类活动的关系极为密切,因此人们对其研究更为重视。有关全新世地层的划分,普遍采用所谓布列特-色尔南德尔方案,把全新世划分为五个气候期,自老至新为: 亚北极期(或称前北方期):寒冷;北方期:干而温;大西洋期:湿而暖;亚北方期:干而温;亚大西洋期:湿而凉。波斯特(L. V. Post,1944)研究南波罗的海泥炭沼泽的孢粉.
基金financially supported by the National Natural Science Foundation of China (Nos. 41306063 and 41330964)by the China Geological Survey (Nos. GZH200900501 and GZH201100203)
文摘Based on the stratigraphic sequence formed since the last glaciation and revealed by 3000 km long high-resolution shallow seismic profiles and the core QDZ03 acquired recently off the southern Shandong Peninsula, we addressed the sedimentary characteristics of a Holocene subaqueous clinoform in this paper. Integrated analyses were made on the core QDZ03, including sedimentary facies, sediment grain sizes, clay minerals, geochemistry, micro paleontology, and AMS 14 C dating. The result indicates that there exists a Holocene subaqueous clinoform, whose bottom boundary generally lies at 15–40 m below the present sea level with its depth contours roughly parallel to the coast and getting deeper seawards. The maximum thickness of the clinoform is up to 22.5 m on the coast side, and the thickness contours generally spread in a banded way along the coastline and becomes thinner towards the sea. At the mouths of some bays along the coast, the clinoform stretches in the shape of a fan and its thickness is evidently larger than that of the surrounding sediments. This clinoform came into being in the early Holocene(about 11.2 cal kyr BP) and can be divided into the lower and upper depositional units(DU 2 and DU 1, respectively). The unit DU 2, being usually less than 3 m in thickness and formed under a low sedimentation rate, is located between the bottom boundary and the Holocene maximum flooding surface(MFS), and represents the sediment of a post-glacial transgressive systems tract; whereas the unit DU 1, the main body of the clinoform, sits on the MFS, belonging to the sediment of a highstand systems tract from middle Holocene(about 7–6 cal kyr BP) to the present. The provenance of the clinoform differs from that of the typical sediments of the Yellow River and can be considered as the results of the joint contribution from both the Yellow River and the proximal coastal sediments of the Shandong Peninsula, as evidenced by the sediment geochemistry of the core. As is controlled mainly by coactions of multiple factors such as the Holocene sea-level changes, sediment supplies and coastal dynamic conditions, the development of the clinoform is genetically related with the synchronous clinoform or subaqueous deltas around the northeastern Shandong Peninsula and in the northern South Yellow Sea in the spatial distribution and sediment provenance, as previously reported, with all of them being formed from the initial stage of the Holocene up to the present.
文摘Based on the analyses of Loss-on-Ignition （LOI）, carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai lake area since the late Last Deglacial Period. The results cover the late Last Deglacial Period and the Holocene. The climate was very unstable and rather arid during the late Last Deglacial Period. The Holocene can be divided into three periods： the early Holocene （11360-8240 cal aB. P. ）, which was dry but unstable and featured rising temperatures, the mid-Holocene （8240-3200 cal aB. P. ）, which was warm and wet and the late Holocene （ since 3200 cal aBP）, which was cold and dry. Results also show a warm-wet event around 1500 cal aB. P.
基金sponsored by the Science and Technology Development Program of the Ministry of Railways(2008G027B),the People's Republic of Chinathe National Key Technology R&D Program(2006BAC13B)103),China
文摘The Longling-Ruili fault is an important active fault in Southwestern China, striking generally northeast. The fault controls the development of the sedimentary series and magmatic action on its two sides, as well as the development of the Longling basin, Mangshi basin and the Zhefang basin along it. Due to limited Quaternary sediments and harsh natural conditions, the study of late Quaternary fault activity on the northern segment of the Longling-Ruili fault is lacking and the time of the newest faulting and the Quaternary slip rate are not clear at present. Based on the interpretation of remote images, quantitative geomorphologic deformation measurements and dating of young terrace deposits and alluvial fans, this paper obtains some new results as follows. The northern segment of the Longling-Ruili fault is a Holocene dextral strike-slip fault with some component of a normal slip. The terrace T1 composing mainly of alluvial deposits formed during 4ka B. P. was offset by the northern segment of the Longling-Ruili fault and its left-lateral and its vertical displacements are 8m - 12m and 2m, respectively. The late Pleistocene alluvial fan was displaced with a left-lateral and vertical displacement of 70m and lgm, respectively. The strike-slip rate of the Longling-Ruili fault is 2.2mm/a 2.5mm/a and the vertical slip rate is 0.6mm/a since the late Pleistocene epoch. The strike-slip rate of the Longling-Ruili fault is 1.8mm/a - 3.0mm/a and vertical slip rate is 0.5mm/a during the Holocene epoch. The proportion of horizontal to vertical displacement is about 4： 1, which means that the vertical slip rate on the northern segment of the Longling-Ruili fault is about 25 % of the horizontal slip rate. The left-lateral slip rate in the late Holocene is consistent with the GPS measurement. The strike slip rate is of great consistency in different time scales since the late Pleistocene epoch, indicating that the activity of the Longling-Ruili fault is of great stability.
