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CHEN QuanHong LI WenHou GAO YongXiang GUO YanQin FENG JuanPing ZHANG DaoFeng CAO HongXia LIANG JiWei 《中国科学D辑(英文版)》2007,50(Z2):47-58
The deep-lake facies of the Yanchang Formation represents a large outflowing lake basin in the Ordos area. Its deposition can be divided into four stages lake genetic and expanding stage, peak stage, inversion stage and dying stage. All the stages are obviously consistent with the evolution of depositional environment and the paleoclimate in the region. The study indicates that the lake basin has evolution fluctuations from highstand to lowstand for four times in its evolution history, and the deposition center of the lake has not obviously moved, staying along the Huachi-Yijun belt. The deep lake sedimentary system mainly consists of deep water deltas and turbidite fans during the entire evolution course of the lake basin in the Late Triassic. The former mainly developed on the slope of steep shore of the delta in the early period of the deep-water expansion and gradually experienced a big shift from deep-water deltas to shallow-water platform delta. And the latter appeared almost in all the above stages and had two types of turbidite fans, slope-moving turbidite fans and slump turbidite fans. The slope-moving turbidite fans have relatively complete facies belts overlapping one another vertically and consist of the slope channel of inter fans, the turbidite channel, inter turbidite channel and turbidite channel front of middle fans and outer fans (or lakebottom plain). However, the slide-moving turbidity fans are formed in the deep lake with their microfacies difficult to be distinguished, and only the center microfacies and edge microfacies can be determined. The two types of the turbidity fans are similarly distributing in the near-root-slope and far-root-slope regions. The deep-lake deposition governs the distribution of the hydrocarbon and reservoir, while the slope-moving turbidite fans are excellent reservoirs for oil-gas exploration due to their great thickness, widespread distribution and accumulation properties. 相似文献
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传统的伪谱(PS)方法,采用傅里叶变换(FT)计算空间导数具有很高的精度,每个波长仅需要两个采样点,而时间导数采用有限差分(FD)近似因而精度较低.当采用大时间步长时,由于时空精度不平衡,PS法存在不稳定性问题.原始的k-space方法可以有效地克服这些问题但是却无法适用于非均匀介质.为了提高原始k-space方法模拟非均匀介质波动方程的精度,我们提出了一种新的k-space算子族.它是用非均匀介质的变速度代替原k-space算子中的常数补偿速度构造得到,引入低秩近似可以高效求解.我们将构造的新的k-space算子应用于耦合的二阶位移波动方程,而不是交错网格一阶速度应力波动方程,使模拟弹性波的计算存储量减少.我们从数学上证明了基于二阶波动方程的k-space方法与基于一阶波动方程的k-space方法是等价的.数值模拟实验表明,与传统的PS、交错网格PS和原始的k-space方法相比,我们的新方法可以在时间和空间步长较大的均匀和非均匀介质中,为弹性波的传播提供更精确的数值解.在保持稳定性和精度的同时,采用较大的时空采样间隔,可以大大降低数值模拟的计算成本. 相似文献
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Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside mesoscale eddies in the Gulf Stream region.The result indicates that average diapycnal diffusivity at 300–540 m depths in anticyclonic eddies reaches4.0×10-5 m2 s-1.This is significantly higher than the 1.6×10-5 m2 s-1 outside eddies and 0.8×10-5 m2 s-1 in cyclonic eddies.Probabilities of diapycnal diffusivity greater than 10-4 m2 s-1 within anticyclonic and cyclonic eddies and outside eddies are29%,5%and 12%,respectively.However,magnitudes of average diapycnal diffusivity at 540–900 m depths in these three cases are of the same order,10-5 m2 s-1.Twenty-four of a total 38 anticyclonic eddies had enhanced mixing in the ocean interior,and 22 were observed during or shortly after strong winds.The coincidence between enhanced mixing and strong wind stress indicates that more wind-induced,near-inertial wave energy propagates downward in anticyclonic eddies.The deeper part of 12 profiles(below 540 m)in anticyclonic eddies had vertical overturns with Thorpe scale exceeding 5 m,among which three profiles had overturns reaching 20 m.Enhanced mixing may have occurred in deep layers of some profiles,although it was not evident in average conditions. 相似文献
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Chen QuanHong Li WenHou Gao YongXiang Guo YanQin Feng JuanPing Zhang DaoFeng Cao HongXia Liang JiWei 《中国科学D辑(英文版)》2007,50(2):47-58
The deep-lake facies of the Yanchang Formation represents a large outflowing lake basin in the Ordos area. Its deposition can be divided into four stages: lake genetic and expanding stage, peak stage, inversion stage and dying stage. All the stages are obviously consistent with the evolution of depositional environment and the paleoclimate in the region. The study indicates that the lake basin has evolution fluctuations from highstand to lowstand for four times in its evolution history, and the deposition center of the lake has not obviously moved, staying along the Huachi-Yijun belt. The deep lake sedimentary system mainly consists of deep water deltas and turbidite fans during the entire evolution course of the lake basin in the Late Triassic. The former mainly developed on the slope of steep shore of the delta in the early period of the deep-water expansion and gradually experienced a big shift from deep-water deltas to shallow-water platform delta. And the latter appeared almost in all the above stages and had two types of turbidite fans, slope-moving turbidite fans and slump turbidite fans. The slope-moving turbidite fans have relatively complete facies belts overlapping one another vertically and consist of the slope channel of inter fans, the turbidite channel, inter turbidite channel and turbidite channel front of middle fans and outer fans (or lakebottom plain). However, the slide-moving turbidity fans are formed in the deep lake with their microfacies difficult to be distinguished, and only the center microfacies and edge microfacies can be determined. The two types of the turbidity fans are similarly distributing in the near-root-slope and far-root-slope regions. The deep-lake deposition governs the distribution of the hydrocarbon and reservoir, while the slope-moving turbidite fans are excellent reservoirs for oil-gas exploration due to their great thickness, widespread distribution and accumulation properties. 相似文献
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Chen QuanHong Li WenHou Gao YongXiang Guo YanQin Feng JuanPing Zhang DaoFeng Cao HongXia Liang JiWei 《中国科学:地球科学(英文版)》2007,50(2):47-58
The deep-lake facies of the Yanchang Formation represents a large outflowing lake basin in the Ordos area. Its deposition can be divided into four stages: lake genetic and expanding stage, peak stage, inversion stage and dying stage. All the stages are obviously consistent with the evolution of depositional environment and the paleoclimate in the region. The study indicates that the lake basin has evolution fluctuations from highstand to lowstand for four times in its evolution history, and the deposition center of the lake has not obviously moved, staying along the Huachi-Yijun belt. The deep lake sedimentary system mainly consists of deep water deltas and turbidite fans during the entire evolution course of the lake basin in the Late Triassic. The former mainly developed on the slope of steep shore of the delta in the early period of the deep-water expansion and gradually experienced a big shift from deep-water deltas to shallow-water platform delta. And the latter appeared almost in all the above stages and had two types of turbidite fans, slope-moving turbidite fans and slump turbidite fans. The slope-moving turbidite fans have relatively complete facies belts overlapping one another vertically and consist of the slope channel of inter fans, the turbidite channel, inter turbidite channel and turbidite channel front of middle fans and outer fans (or lakebottom plain). However, the slide-moving turbidity fans are formed in the deep lake with their microfacies difficult to be distinguished, and only the center microfacies and edge microfacies can be determined. The two types of the turbidity fans are similarly distributing in the near-root-slope and far-root-slope regions. The deep-lake deposition governs the distribution of the hydrocarbon and reservoir, while the slope-moving turbidite fans are excellent reservoirs for oil-gas exploration due to their great thickness, widespread distribution and accumulation properties.
相似文献7.
西藏日土岩基三宫岩石序列地球化学、年代学及构造意义 总被引：3，自引：2，他引：1
西藏日土岩基三宫岩石序列由花岗闪长岩、英云闪长岩、石英闪长岩组成,富含包体,包体由砂板岩捕掳体、角闪石析离体和镁铁质暗色深源包体组成。寄主岩的地球化学性质显示高硅、铝不饱和-弱饱和、钙碱性-高钾钙碱性、富集轻稀土、弱-中等的铕异常,寄主岩地球化学协和图指示岩浆来源为壳幔混源,花岗闪长岩锆石~(206)Pb/~(238)U年龄为115.5±0.4Ma,该混源花岗岩序列与狮泉河带闭合过程中岛弧与班戈地体的碰撞有关。 相似文献
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对太平洋CC区西部7根沉积物短柱样的常微量元素进行浓度测试,以了解沉积物元素时空分布特征及其来源和控制因素。与上地壳元素平均值（UCC）相比,研究区沉积物中MnO、P2O5、Co、Ni、Cu、Mo、Ba明显富集,Al2O3、K2O、Fe2O3、CaO、Sr等亏损。聚类和因子分析表明研究区沉积物元素有4种来源,其中Al2O3、Fe2O3、K2O、MgO、TiO2、V、Cr、Co、Rb、Zr、Nb、Cs、Hf、Ta、Pb、Th、U为陆源黏土成因;CaO和Sr为钙质生物成因;MnO、P2O5、B、Ni、Cu、Zn、Mo、Ba为海水自生成因;Na2O为火山—热液成因。10.2° N以北沉积物元素为陆源黏土、海水自生和钙质生物成因,而10.2° N以南沉积物元素为陆源黏土、海水自生和火山—热液成因。沉积物中陆源物质主要来自亚洲高空气流携带的风尘物质。沉积物中海水自生成因的金属元素富集,与富氧的南极底流有关。柱样中CaO、Sr含量的时空变化,与柱样所处水深、冰期生产力和碳酸钙补偿深度变化有关。柱样中Ba/Ti指示的火山—热液活动在地质时期呈减弱的趋势,其对沉积物的影响也向北减弱。 相似文献
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Zheng YouYe Xu RongKe Wang ChengYuan Ma GuoTao Lai XuLong Ye DeJin Cao Liang Liang JiWei 《中国科学D辑(英文版)》2007,50(12):1767-1772
Most geologists believe that there are no Early and Middle Triassic strata in the W. Gandisê stratigraphic subregion, but the present authors have found Early Triassic conodonts for the first time in the Shiquanhe area, including five conodonts genera (Form genera): Pachycladina, Neohindeodella, Cornudina, Hadrodontina and Hibbardella sp. etc. Then we affirm that Early Triassic deposits exist in the Gandisê stratigraphic subregion, and establish the Tangnale Formation. The conclusion is new important complementary basal data for Triassic stratigraphy division of Gangdisê, reconstructing palaogeography and studying Gangdisê from Paleozoic to Mesozoic island-arc evolution and transi-tion. 相似文献
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中-晚侏罗世随着劳亚大陆与冈瓦纳大陆的裂解、北大西洋的开启以及古特提斯洋的闭合,导致全球海平面的改变和气候波动。在中-晚侏罗世交界的卡洛期-牛津期,西特提斯域广大地区的气候从冷湿转变为干热,羌塘盆地位于特提斯喜马拉雅构造域东段,它是否也有类似的气候变化特征?文章对羌塘盆地雁石坪剖面中、上侏罗统夏里组沉积物中Ca CO3、赤铁矿和针铁矿环境代用指标进行了测定,并结合岩性和沉积相变化分析了该区古气候变化,研究结果表明:中-晚侏罗世交界时期,羌塘盆地雁石坪地区气候变化经历了早期(163.8~162 Ma)相对冷湿、中期(162~161.4 Ma)半干旱以及晚期(161.4~159.6 Ma)干旱3个演化阶段。显示羌塘盆地中-晚侏罗世交界时期(163.8~159.6 Ma)的气候变化与同一时期的西特提斯构造域气候变化趋势一致,为羌塘盆地侏罗纪可能的成盐潜力研究和评价提供了重要的古气候依据。 相似文献
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