The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change   总被引：3，自引：0，他引：3  

WenXia Han  LuPeng Yu  ZhongPing Lai  David Madsen  Shengli Yang 《Quaternary Research》2014

The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0–7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0–7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.  相似文献   

Experimental and theoretical investigations on high-pressure phase transition of Sr2Fe2O5     

Feng Zhu  Ye Wu  Xiaojing Lai  Shan Qin  Ke Yang  Jing Liu  Xiang Wu 《Physics and Chemistry of Minerals》2014,41(6):449-459

Sr₂Fe₂O₅ is a typical oxygen-deficient perovskite and adopts brownmillerite phase (Ibm2, Z = 4) at ambient conditions. Its high-pressure structural behavior has been investigated by both synchrotron radiation X-ray diffraction with diamond anvil cell technique and first principles calculations. Experimental results clearly show that the brownmillerite Sr₂Fe₂O₅ transforms into a tetragonal perovskite-type phase at 12.0 GPa and room temperature, and then into a Sr₂Mn₂O₅-type phase (Pbam, Z = 2) at 23.3 GPa after high-temperature annealing. The Sr₂Mn₂O₅-type phase is stable up to at least 60 GPa and it further undergoes a reversible transition to a lower symmetry phase at 79.1 GPa and ~2,000 K. The results from theoretical calculation not only confirm that the tetragonal phase of Sr₂Fe₂O₅ is isostructural with the high-temperature structure of Ba₂In₂O₅ (I4/mcm, Z = 4), but also predict a series of phase transitions from brownmillerite phase to Ba₂In₂O₅-type phase at 6.9 GPa, and then to Sr₂Mn₂O₅-type phase at 19.7 GPa, which coincides with present experiment results. Isothermal pressure–volume relationship of the Sr₂Mn₂O₅-type phase can be well described by the Birch–Murnaghan Equation of State with V ₀ = 111.6(10) ų, B ₀ = 122(9) GPa, B ₀ ^′  = 4(fixed) experimentally and V ₀ = 115.8(3) ų, B ₀ = 92(4) GPa, B ₀ ^′  = 4(fixed) theoretically. The transition mechanism from brownmillerite to Ba₂In₂O₅-type phase is the displacement of four-coordinated Fe³⁺ ions to higher coordinated positions upon compression. In addition, a semiconductor-to-metal crossover is predicted from brownmillerite to Ba₂In₂O₅-type or Sr₂Mn₂O₅-type phase.  相似文献   

山东济宁三号煤矿上组煤水文地质条件分析     

宋友凯  ;来永伟  ;刘艳  ;孔庆虎  ;李本军  ;齐荣贵 《中国煤炭地质》2014,(7):45-51

济宁三号煤矿目前开采的煤层为上组煤的3煤(3上、3下煤),自投产以来,发生多次涌水,如13下01综放面侏罗系底部含水层最大涌水量达533.84m3/h,63下01综放3煤顶板砂岩最大涌水量527m3/h,曾一度出现工作面局部被淹而导致停产,对矿井的安全高效生产构成了极大的威胁。在综合分析研究上组煤顶板各含水层的水文地质特征和充水条件的基础上,认为上组煤(3上、3下煤)开采时的直接充水水源为3煤顶板砂岩含水层;间接充水水源是侏罗系含水层水以及局部地区对侏罗系含水层起补给作用的第四系含水层;部分地区侏罗系含水层被采动裂隙导通而成为直接充水水源,大部分地段第四系底部均为粘土,有效的阻隔了第四系与下伏侏罗系含水层的水力联系,对下伏含水层补给微弱;充水通道主要有断层、采动裂隙、封闭不良钻孔和破坏的井筒。为指导下一步煤矿生产预防水害事故提供了依据。  相似文献   

Numerical analysis for cooling effect of open boundary ripped-rock embankment on Qinghai-Tibetan railway   总被引：6，自引：0，他引：6  

Lai?Yuanming?Email author  Zhang?Mingyi  Liu?Zhiqiang  Yu?Wenbing 《中国科学D辑(英文版)》2006,49(7):764-772

At present, the Qinghai-Tibetan railway is being built, and it will pass across more than 550-km perma-frost regions. Therefore, the key to the stability of therailway embankment lies in solving the permafrost problem. Because global warming and existence of railway tend to degrade the permafrost in these re-gions[1], more difficulties and problems are induced in the construction and maintenance of railway. In the area where the mean annual air temperature is higher than a certain value, the …  相似文献   

高频基准面旋回控制下浅水三角洲及其砂体发育模式:以松辽盆地扶余油田白垩系泉头组为例^*          下载免费PDF全文

赖洪飞  秦智  王洪君  郑锡  林艳波  鲍志东  李美俊  张云龙  张莉  吴煜潇  宋健  何陵沅 《古地理学报》2017,19(4):609-622

浅水三角洲储集层在陆相湖盆油气勘探中具有重要的意义,但基于密井网资料的精细研究仍十分缺乏。以高分辨率层序地层学和沉积学理论为指导,以松辽盆地扶余油田DT91区块白垩系泉头组四段第Ⅲ砂组14余口取心井的岩心资料和700余口密井网测井资料为对象,分析了高频基准面旋回下浅水三角洲及其砂体的发育规律。研究结果表明: (1)浅水三角洲储集层主要发育在河道、漫溢砂、分流砂坝、天然堤、决口扇和席状砂等6种成因砂体,以河道砂体和分流砂坝砂体为主。(2)在岩心和测井曲线上可识别出河道底部冲刷面、进积—退积作用面、退积—进积作用面和湖泛面等4种基准面旋回物理界面;并识别出3大类、7亚类超短期基准面旋回类型。(3)高频基准面旋回演化过程中,湖泊浅水三角洲沉积区可容空间变化不大,沉积物供给通量在可容空间增长速率(accommodation increasing rate,A)和沉积物供给通量(sediment supply rate,S)的比值A/S变化中起着主导作用,进而控制着成因砂体的数量和空间接触关系。当A/S值由小变大时,浅水三角洲的规模快速变小,成因砂体的数量也相应减少;同时,成因砂体垂向接触方式由下切叠加式→加积叠加式→孤立式变化,砂体平面分布的复合连片程度也发生由高到低的变化。  相似文献   

Experimental investigation of fine sediment deposition using particle image velocimetry     

Masoumeh MoayeriKashani  Lai Sai Hin  S. Ibrahim 《Environmental Earth Sciences》2017,76(19):655

In order to create natural and healthy water ecosystems, the impact of hydrological processes in ponds must be identified. Pond structure may affect water quality in many ways. The present study provides a novel insight into some of the hydrological processes as well as how to employ retentions to enhance storm water detention and manage discharge. In this research, particle image velocimetry is utilized to study the two-dimensional collecting efficiency of fine sediments by retention structures with a range of hydraulic features. To examine the hydrodynamic behavior of water mixed with fine particles, a sediment basin was designed. Fluorescent polymer particles (1–50 μm) were subsequently added to this fluid mix. This study demonstrates that gravitational force increases fine particle settlement by over 50% at greater depths. The optimum collecting efficiency of sediments at the water surface was found to be around 80%. It was also determined that flow rate and particle size are directly correlated and that inlets and outlets at higher levels impede fine particle dispersion in the water column. For these reasons, it seems that adjusting the hydraulic parameters may diminish siltation.  相似文献   

Characteristics of seismic disasters and aseismic measures of tunnels in Wenchuan earthquake     

Jinxing Lai  Siyue He  Junling Qiu  Jianxun Chen  Lixin Wang  Ke Wang  Junbao Wang 《Environmental Earth Sciences》2017,76(2):94

Over the past few years, accompanied by big and frequent earthquakes, more attention was paid to the tunnel earthquake resistance. To reduce tunnel seismic damage and explore the reasonable aseismic measures, the tunnel earthquake disaster investigation was employed to analyze and summarize the tunnel seismic damage on the basis of Wenchuan earthquake. Fifty-two tunnels near the epicenter of Sichuan Province were investigated: Only 7 tunnels did not show structure damage, 6 tunnels suffered the most serious damage, and the rest appeared damage to various extents. It indicates that most serious seismic damage happens to fault fracture zone, followed by entrance and common section of the tunnel. Additionally, the results display that the typical seismic damage of tunnels is lining cracking, collapsing, dislocation, construction joints cracking, and uplifting of invert, and usually lining cracking and collapsing account for a larger proportion. Therefore, the tunnel aseismic design should emphasize the fault fracture zone and tunnel entrance. Tunnel design should adopt the composite lining structure with shock absorber and whole chain alternative grouting to prevent the lining cracking and collapsing in the seismic fortification zone.  相似文献   

Discrete element simulation of mine tailings stabilized with biopolymer     

Rui Chen  Xiaobin Ding  Lianyang Zhang  Yongli Xie  Hongpeng Lai 《Environmental Earth Sciences》2017,76(22):772

This paper presents a series of numerical simulations using discrete element method (DEM) to study the behavior of biopolymer-stabilized mine tailings (MT). Validation is conducted by comparing the DEM results with the experimental data. The macro-behavior comparison shows that the DEM simulations are in good agreement with experimental results. Analysis of the micro-parameters indicates more biopolymer induces larger tensile and shear strengths, confirming the experimental results which show that the strength of MT increases with higher biopolymer concentration. Analysis of the bond breakage pattern suggests that at the same strain level MT stabilized with higher biopolymer concentration show less bond breakage percentage. MT specimen under greater confining pressure develops larger shear band than that under lower confining pressure. Higher biopolymer concentration induces the increase in larger inter-particle bonding strength and thus larger cracking resistance and greater macro-strength.  相似文献   

Exploring Earth’s boundaries with Donald V. Helmberger          下载免费PDF全文

Voon Hui Lai 《地震科学（英文版）》2022,35(1):63-66

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Machine-learning-enabled discrete element method: Contact detection and resolution of irregular-shaped particles     

Zhengshou Lai  Qiushi Chen  Linchong Huang 《国际地质力学数值与分析法杂志》2022,46(1):113-140

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