The deep-lake deposit in the Upper Triassic Yanchang Formation in Ordos Basin, China and its significance for oil-gas accumulation

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.     

The microtine distribution and its environmental significance since the Middle Pleistocene in Zhangping Caves of the Qinling Mountains

Three microtine species are recovered from the Zhangping Caves of the Qingling Mountains, namely Microtus oeconomus, Caryomys inez and Caryomys eva. They are climate-sensitive ones with different ecological habits, therefore their distribution well corresponds to environmental variations. Statistical comparison of the distribution of fossil microtines and their counterparts nowadays displays that the climate variation of the studied area and its contiguity since the middle Pleistocene are: warm and humid at 493 ka ago, cool and humid at 259 ka ago―cold and humid at 205 ka ago―cool and humid at 28 ka ago, and warm and dry at present.     

基于卷积神经网络的地震震级测定研究

地震预警震级测定是地震预警系统最重要也是最困难的部分之一.本文提出了基于卷积神经网络的地震预警震级测定方法,将震级测定问题转化为震级分类问题,即将ML＞2.0的震级分成20个不同等级类别处理.收集了福建台网2012-2019年期间记录到福建、台湾海峡及台湾共1928个地震作为研究资料,经过台站记录截取、大震样本增强、标签制作、质量筛选等预处理共得到14644条三分向地震样本记录;构建了3 s波形输入的卷积神经网络震级预测模型,并用2012-2018年震例对模型进行训练,用2019年震例对模型进行测试.结果 表明,单台震级偏差有85.6％可控制在±0.3以内,前三台平均的震级偏差有91.8％可控制在±0.3以内,其中震级较大偏差的事件多为缺乏历史样本.相较于传统方法,该模型测定的震级值更加稳定可靠,可为解决地震预警震级测定这一挑战性难题提供新的技术手段.     

The deep-lake deposit in the Upper Triassic Yanchang Formation in Ordos Basin,China and its significance for oil-gas accumulation

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.     

The deep-lake deposit in the Upper Triassic Yanchang Formation in Ordos Basin,China and its significance for oil-gas accumulation

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.

     

甘肃省文县阳山金矿床地质地球化学研究

对阳山金矿床进行的地质学、地球化学研究表明,矿石中金主要以微细粒金(2～3 μm)包裹于毒砂、黄铁矿等矿物之中;矿石中As、Sb及有机碳含量较高,且Au与Ag、As、Hg、Sb等低温热液元素相关性明显.流体包裹体均一温度为150～250 ℃、盐度w(NaCleq)为1.6%～6.5%,流体包裹体成分以H2O和CO2为主,含少量CO、CH4、H2.黄铁矿、辉锑矿δ34S值为-3.47‰～+13.23‰;石英δ18O值为-3.09‰～+0.41‰,δD值为-92.4‰～-62.9‰;全岩δ13C值为-2.19‰～-9.14‰,δ18O值为-13.54‰～-9.06‰.反映了成矿流体为低温、低盐度热液,其组成以大气降水为主,并有岩浆热液参与,成矿物质来自泥盆系地层及燕山期岩浆岩体,矿床为受构造直接控制的、与沉积作用及燕山早期岩浆活动有成因联系的叠加改造型微细浸染型金矿床.     

基于气枪信号偏振特征的震相自动判别研究

气枪震相拾取是地下结构探测的一项基础性工作,震相拾取的精度和波组类型的可靠度是速度结构反演的关键.本文提出了基于偏振特征的气枪震相自动识别方法,通过将水平分量旋转为径向和切向分量,由垂向分量和径向分量构成的偏振特征量初步判别P波组和S波组,根据质点运动轨迹确定出偏振角和偏振线性度参数,针对偏振角大小判别出具体波组类型 ...     

Nanpoping fauna of the Lanzhou Basin and its environmental significance

The Asian monsoon-arid environment system began to develop during the Oligocene, but the exact position of the arid zone boundary is uncertain in the Oligocene. Fossil mammal assemblages can be used to assess the environment of an area. There were two sizes of mammals in the Nanpoping fauna from the Oligocene strata of the Lanzhou Basin: the small ones were grassland rodents such as Ctenodactylidae; the large ones were forest dwellers such as Paraceratherium and Paraentelodon. Of the 23 species of mammals identified in the Nanpoping fauna, ~40% were forest dwellers and the rest (~60%) were grassland taxa. The Nanpoping fauna was compared with the contemporaneous Dingdanggou fauna in the Danghe area to the north and Jiaozigou fauna in the Linxia area to the south. The Nanpoping fauna contains elements of both other faunas and thus represents a transitional assemblage between forest and grassland. So, it can be inferred that the southern boundary of the arid zone in China during the Oligocene was probably near the Lanzhou Basin.     

高铁地震面波相速度频散曲线提取

为了充分利用高铁地震信号中的面波信息,本文将双台法和旋转法等面波相速度提取方法应用于高铁地震模拟记录,尝试提取基阶瑞利波与勒夫波相速度频散曲线.通过分析以高铁高架桥的桥墩为源的高铁波场干涉特征,给出了适用于高铁地震波场的面波相速度校正方法;通过数值实验,证明了方法的有效性.