A grain-size record from Beijing region in Northern China: Late Quaternary paleoclimate oscillation in response to global change

Numerous samples taken from one core at the Beijing plain were utilized to characterize the paleoclimatic configuration of the study area and its possible relation to global control since the last interglaciation. We presented here a detailed grain-size record for the full length of Late Pleistocene, along with the optical simulated luminescence (OSL) dating. Our findings revealed that Late Pleistocene of the study area started approximately at 110 ka B.P. represented by the thick sediments of 31 m in Changping depression. Four sedimentary cycles were outlined in the core during Late Pleistocene, corresponding to marine isotope stage (MIS) 5 to 2. Controlled by regional geology and global climatic setting, eight paleoclimatic periods were identified simultaneously in the study area on the time scale of 10⁴ year, with the warm and moist climate being found at 110 — 96, 92 — 76, 67 — 56, and 28 — 18 ka B.P.. The climatic instabilities on a millennial scale in Late Pleistocene were characterized largely by the occurrence of 6 strong Heinrich events shown by comparatively coarse groups. These variations correlate well with those documented in the GRIP Greenland and in the Northern Atlantic Ocean, though more complex features may exist on the long time scale.     

Holocene environmental change inferred from the loess–palaeosol sequences adjacent to the floodplain of the Yellow River, China

Chinese loess deposits are generally considered to be the product of dust storms and dust falls from the central Asia arid zones that were transported across China by the northwesterly continental monsoon. In contrast, the Zhengzhou Loess found southeast of the Loess Plateau, adjacent to the floodplain of the Yellow River, records a different eolian regime and dust source. The Zhengzhou Loess was investigated by field observations, measurements of magnetic susceptibility, particle-size distribution, loss-on-ignition, CaCO₃ and chemical contents. Both field observations and the laboratory results indicate that, during the last glacial, the Zhengzhou Loess was supplied by two different eolian regimes and dust sources, one was from the fresh flood deposits of the Yellow River driven by the northeast winds from the low-lying floodplain, and the other was from the dust storms and dust falls that traveled across the Loess Plateau driven by the northwesterly continental monsoon from the central Asian arid lands. The early Holocene, 11,500–8500 a BP, was a transition during the change in eolian regime and dust source because of the weakened northwesterly monsoon along with the global climatic amelioration. Following the retreat of the northwesterly monsoon from the onset of the mid-Holocene Climatic Optimum at 8500 a BP, dust supply from the drifting sand zone on the Yellow River floodplain became dominant because of the intensified strength of the northeast winds from the Bohai Sea. From 3100 a BP onwards, climatic aridity and extensive human disturbance have resulted in intensive eolian processes causing the incursion of the drifting sand into the Zhengzhou Loess zone. These results show that loess accumulation is more complex than traditionally assumed. The origin of loess deposits elsewhere outside the Loess Plateau may be related to dust sources derived from alluvial sediments of major river systems.     

东亚地区YoungerDryas气候突变的数值模拟研究

YoungerDryas(YD)气候突变事件是近两万年中一次全球性的气候急剧变冷事件。文章试图在东亚地区YD事件的若干证据基础上,从海洋、冰盖和大气的热力学以及动力学角度出发,利用气候模拟方法就东亚地区YD气候突变的机制和一些成因假说进行敏感性试验。模拟结果表明,因淡水通量异常引起的海洋表面温度降低是YD形成的直接原因。海洋大气耦合作用对于YD传播强度及时间不同步具有重要作用。除北大西洋淡水通量异常的作用外,南半球海洋的淡水通量异常可能对东亚地区的YD事件有着更重要的贡献。海洋耦合大气环流模式模拟表明,东亚与欧洲降温具有不同步性,最大变化速率欧洲达到-0.122℃/a,东亚地区为-0.067℃/a。模拟结果与东亚地区YD时期的气候记录在特征上能够进行对比,反映了模拟试验的边界和强迫条件的设计接近东亚古气候状况,因而模拟结果对分析海洋、冰盖和大气的热力学以及动力学探讨揭示YD气候事件的物理机制和动力原因具有可靠的依据。     

A Preliminary Review of Metallogenic Regularity of Silver Deposits in China

China has widely distributed silver deposits,and is rich in silver resources.Although silver deposits are mainly associated with Pb-Zn deposits,a number of independent silver deposits have also been discovered in recent years.Silver deposits include different types,such as submarine volcanism and continental volcanism related type,intrusion related type,and sedimentary related type.This study summarized the metallogenic regularity of China’s silver deposits systematically based mainly on the data from 490 silver deposits.It is shown that submarine volcanic sedimentary type,continental volcanic or sub-volcanic type,skarn type,hydrothermal type(including vein type and stratabound type),sedimentary metamorphic type,sedimentary type and regolith type should be regarded as the most important prediction types of silver deposit.A total of 32 silver mineralization belts and 111 silver concentration areas have been delineated.The map of "Spatial distribution of silver mineralization belts in China" and other series of maps finished in this study may provide a theoretical basis for the evaluation and prognosis of silver resources potential in China.     

Parallelized combined finite-discrete element (FDEM) procedure using multi-GPU with CUDA

This paper focuses on the efficiency of finite discrete element method (FDEM) algorithmic procedures in massive computers and analyzes the time-consuming part of contact detection and interaction computations in the numerical solution. A detailed operable GPU parallel procedure was designed for the element node force calculation, contact detection, and contact interaction with thread allocation and data access based on the CUDA computing. The emphasis is on the parallel optimization of time-consuming contact detection based on load balance and GPU architecture. A CUDA FDEM parallel program was developed with the overall speedup ratio over 53 times after the fracture from the efficiency and fidelity performance test of models of in situ stress, UCS, and BD simulations in Intel i7-7700K CPU and the NVIDIA TITAN Z GPU. The CUDA FDEM parallel computing improves the computational efficiency significantly compared with the CPU-based ones with the same reliability, providing conditions for achieving larger-scale simulations of fracture.     

Risk evaluation of dam-break environmental impacts based on the set pair analysis and cloud model

Natural Hazards - Many dams have been constructed around the world. Compared with the potential losses of life and economy, the environmental impacts caused by dam breach were less analyzed. As a...     

柴达木盆地3万年左右Ilyocyprisinermis灭绝事件及其古环境意义

柴达木盆地东南部的达参 1井 4 6 m处 ,介形类 Ilyocyprisinermis突然大量灭绝 ,使得介形类总体丰度大大减少 ,介形类生态组合也发生了明显的变化。该事件称为 Ilyocypris inermis灭绝事件 ,其年限约为 3万 a左右 ,具有十分重要的古环境意义。它是更新世晚期全球气候急剧恶化在柴达木盆地的反映 ,证明了柴达木盆地气候演化和全球气候具有同步性 ;另一方面 ,也为 3万 a左右青藏高原的隆升提供了微古生物方面的证据     

中扬子地区显生宙构造演化及其对油气系统的影响

中扬子地区作为南方海相油气勘探的重点战略区块 ,自基底形成至今 ,陆块南北经历了多期造山活动。其中 ,古生代以来的后四期造山作用控制与发育了区内海陆相四套含油气系统 ,加里东及印支早期造山作用利于原生海盆含油气系统的发育与形成 ;印支晚期—喜山期造山作用对其具有改造和破坏作用 ,但利于陆相含油气系统的形成。研究区海盆发育期形成的古隆起及其周缘斜坡带是海相残留盆地油气运聚与保存的有利场所     

白云鄂博矿床白云岩的Sm—Nd、Rb—Sr同位素体系

白云鄂博矿床的年龄和成因长期争论.本文报道了白云鄂博矿床白云岩及其组成矿物的Sm-Nd、Rb-Sr同位素分析结果.采自该矿床主、东矿等地的15个白云岩样品的Sm-Nd同位素分析结果呈现一条等时线,等时年龄1273±100(2σ)Ma,INd=0.510919士36(2d),MSWD1.01.全岩Rb-Sr同位素分析结果分散,不构成等时线.87Rb/86Sr0～2.092×100-2,87Sr/86Sr0.70341～0.70541.白云岩矿物的Sm-Nd同位素分析结果给予了与全岩类似的Sm-Nd等时年龄,t=1250士210(2σ)Ma,1Nd=0.510914±77(2σ),MSWD 0.56.白云鄂博矿床可能是中元古代末期大离子亲石微量元素略为富集地幔源区部分熔融岩浆活动产物.