欧亚大陆中部盆地群大剖面的编制及其构造意义

盆地结构记录了盆地演化特征,盆地群结构和构造特征由其所处的构造背景和板块边界决定。随着油气勘探的不断深入,积累了大量地震剖面,为盆地群剖面特征对比,提供了大量的基础资料。本文从大地构造背景着手,通过筛选地震与地质剖面,大致沿北纬39°绘制了欧亚大陆东西向剖面(在东部北黄海盆地有向南的偏转):西起黑海盆地,东至琉球海沟,剖面长约12000km,横穿18个盆地,涵盖克拉通盆地(塔里木原型盆地等)、裂谷盆地(太原盆地、渤海湾盆地等)、前陆盆地(黑海盆地、南里海盆地等)和弧后盆地(东海盆地)等多种盆地类型。其中,陆壳上的盆地发育在前寒武基底上,演化历史悠久;褶皱基底、洋壳基底和洋陆过渡壳基底上发育的盆地主要发育在中新生代。通过详细对比剖面各段结构和构造演化特征,发现中新生代构造活动决定了欧亚大陆中部盆地群最终格架,盆地多具有多期叠合改造的特征。剖面西段盆地群普遍具有中生代伸展断陷,叠加后期挤压坳陷的特征;剖面东段盆地群具有中生代断陷,叠加后期坳陷的特征。现今构造格架由西到东表现为前陆坳陷到弧后坳陷,鄂尔多斯盆地和沁水盆地是本剖面线结构特征分段的枢纽。

四川盆地超深地震大剖面勘探及深部地质结构研究

为了研究四川盆地中部地震诱发因素,了解沉积盖层到莫霍界面的地震反射信息,近年来部署了2018GJ和2009HN两条超深地震大剖面勘探测线,获得了沉积盖层、岩石圈及莫霍界面的深部地震信息,全景式地再现了四川盆地中部岩石圈结构具明显的3大界面(基地、康拉德界面、莫霍面),4大层系(沉积盖层、上地壳和下地壳、上地幔),对四川盆地深部地质结构,特别是康纳德界面及莫霍界面地质特征有了新的初步认识,为研究四川盆地中部地壳结构和地震诱发因素提供了可靠的基础资料。

松潘—邵阳大地电磁剖面深、浅部典型构造的解释

通过对松潘—邵阳大剖面大地电磁原始资料的采集、分析、MT二维反演成图,进而对大剖面MT反演图进行综合地质解释,解释成果客观的反映了剖面区带深,浅部构造的展布规律并取得了如下几个方面的认识:(1)确定了龙门山推覆构造主滑脱面为埋深为20km的壳内低阻层;(2)查清了华蓥山构造带深,浅部断裂展布特征;(3)系统揭示了剖面区带隐伏断裂的发育情况;(4)对剖面区带的断裂活动性进行了分级;(5)揭示了川东—鄂西—湘中地区深、浅部褶皱构造的展布。

大数据体压缩和存储算法在地震剖面中的应用

为了提高抽取地震剖面的速度,首先采用字节压缩,把任意的浮点数(IEEE和IBM格式)转换一字节的整数的方法对数据体进行压缩;然后,采用八叉树算法对数据体分块,在八叉树中递归查找需要显示数据文件,完成数据体的抽取显示。

盐穴平面图中3个关键要素绘制的研究

盐穴平面图是进行盐穴适用性、安全性和稳定性评价和分析的基础。目前,我国对盐穴平面制图中应该表达何种要素以及如何表达这些要素尚在研讨当中。文中结合国内外各种盐穴平面图件,参考德国盐穴平面制图标准,研究盐穴制图体系中盐穴水平投影轮廓线和水平投影最大剖面以及相邻盐穴空间最短距离3个问题,采用基于ObjectARX的AutoCAD二次开发技术加以实现。经过盐穴实测数据验证,文中方法能稳定、快速、准确地解决以上问题。

下扬子地区中—新生代构造变形单元及构造变形样式

下扬子地区地处扬子板块东部,其构造变形特征研究具有重要意义。综合利用区域地质、地震、钻井和地球物理等多方面资料,对下扬子地区断裂、地层发育特征精细解释,建立了贯穿研究区的两条区域地质剖面,即宿迁—绍兴大剖面和连云港—苏州大剖面。研究表明:下扬子地区可划分为6个一级构造变形单元,依次为苏北—胶南造山带、苏北冲断区、南北对冲带、苏南冲断区、浙北冲断区和江南造山带,并可进一步细分为14个二级构造变形单元,这些明确表现出本区中、新生代对冲构造变形特征;两条区域大剖面表现出了挤压、伸展、反转等3类典型构造变形样式,具体可分为5亚类、10小类。

塔里木盆地深层地质结构特征与资源潜力

为查明塔里木盆地深层地质结构特征,预测深层油气资源潜力,中国地质调查局油气资源调查中心联合中石油、中石化及相关科研院所开展了盆地骨干地震大剖面拼接处理工作,形成覆盖全盆地34条高品质骨干地震大剖面,长约1.72×10^(4)km。分析塔里木盆地深层地质结构特征,评价深层资源潜力,结果如下:(1)将柯坪断隆划分为塔里木盆地一级构造单元。提出盆地“五隆五坳”构造单元划分方案。柯坪断隆与巴楚隆起古生界地震反射特征及电性特点基本一致,具相同基底性质。地层序列与巴楚隆起-西南坳陷相近,古生界构造演化与属性与塔里木盆地相似,后期隆升特征明显,构造单元界线清晰;(2)评价深层震旦系和寒武系油气远景资源量为242×10^(8)t油当量。首次评价震旦系远景资源量为60×10^(8)t油当量,优选出柯坪断隆、古城台缘带、阿满过渡带和塔中隆起4个深层有利领域和柯坪、塔中、轮深、和田河、古城、吐木秀克-乔来买提、玉东、巴东8个深层有利区带,为开展深层油气资源勘查提供了资源基础和目标方向;(3)构建塔里木盆地大数据平台,解决了大数据整合和智能化综合应用问题。建立物探、钻井、地调、勘探成果等数据库、图形库,建立了三维盆地地质模型。集成开发相应的计算机软件模块库,实现地质建模、盆地模拟、资源评价、目标优选、钻前预测的流程化、智能化。研究成果实现了盆地基础资料共享与融合,为盆地整体研究和深层资源评价提供了扎实资料,提升深层油气成藏理论认识水平,以实现石油企业深层油气勘查突破。

“多元法”建立南海区域地层格架及其研究意义

受勘探资料品质及分布范围所限,南海南、北地层一直未能统一。本文以覆盖南海的区域地震大剖面为基础,采用"多元法"综合多种地球物理资料开展地震地质层位标定和对比、解释,即根据高勘探程度区(珠江口、琼东南、曾母、礼乐等盆地)引层、其他探区(北康、南薇西等盆地)层位辅助标定、ODP(大洋钻探)资料标定及磁异常条带定年,建立南海区域地层格架,在新生界共识别出六套地震反射层,总结了界面地震反射特征。研究结果表明:南海新生代受新南海扩张控制,共发育前扩张期、扩张期以及后扩张期三套地层,地层展布具有老地层分散、新地层广泛分布的特点,对南海南、北地层统一、南海盆地新方案划分及南海深部莫霍面研究等具有参考意义。

Tectonic Evolution of the North Depression of the South Yellow Sea Basin Since Late Cretaceous

Abstract On the basis of subsidence history analysis and balanced cross-section analysis, the vertical uplift/subsidence history and horizontal extension/compression history of the north depression of the south Yellow Sea basin are quantitatively studied. The results show that the tectonic evolution of the north depression of the south Yellow Sea basin since late Cretaceous can be divided into a rifting phase （late Cretaceous to Paleogene） and a post-rifting phase （Neogene to Quaternary）. The rifting phase can be further subdivided into an initial rifting stage （late Cretaceous）, an intensive rifting stage （Paleocene）, a rifting termination stage （Eocene）, and an inversion-uplifting stage （Oligocene）. Together, this division shows the characteristics of an episodic-evolved intracontinental rift-depression basin. The deformation of the north depression of the south Yellow Sea basin since late Cretaceous was mainly fault-related. The horizontal extension and tectonic subsidence were controlled by the activity of faults. The differential evolution of faults also caused variations in local uplift/subsidence movements and the regional heterogeneity in extension. The late Cretaceous initial rifting of the north depression of the south Yellow Sea basin is related to the Pacific-Eurasia convergence. From the Paleocene intensive rifting stage to present, the Pacific-Eurasia convergence and India-Eurasia convergence have played important roles in the evolution of this region.

Supercooled water in austral summer in Prydz Bay,Antarctica

Supercooled water with temperatures below freezing point, was identified from hydrographic data obtained by Chinese and Australian expeditions to Prydz Bay, Antarctica, during the austral summer. The study shows that most supercooled waters occurred at depths of 63-271 m in the region north of the Amery Ice Shelf （AIS） front. The maximum supercooling was 0.16℃ below the in-situ freezing point. In temperature and salinity ranges of-2.14 - -1.96℃ and 34.39-34.46, respectively, the water was colder and fresher than peripheral shelf water. The supercooled water had less variability in the vertical profiles compared to shelf water. Based on analysis of their thermohaline features and spatial distribution, as well as the circulation pattern in Prydz Bay, we conclude that these supercooled waters originated from a cavity beneath the AIS and resulted from upwelling just outside of the AIS front. Water emerging from the ice shelf cools to an extremely low temperature （about -2.0℃） by additional cooling from the ice shelf, and becomes buoyant with the addition of melt water from the ice shelf base. When this water flows out of the ice shelf front, its upper boundary is removed, and thus it rises abruptly. Once the temperature of this water reaches below the freezing point, supercooling takes place. In summer, the seasonal pycnocline at -100 m water depth acts as a barrier to upwelling and supercooling. The upwelling of ice shelf outflow water illuminates a unique mid-depth convection of the polar ocean.

Temporal variations in internal tide multimodal structure on the continental shelf, South China Sea

Temporal variations in multimodal structures of diurnal( D_1) and semidiurnal( D_2) internal tides were investigated on the continental slope of the Dongsha Plateau, based on 2-month moored acoustic Doppler current profiler observations. Harmonic analysis indicated that the D_1 components( K_1 and O_1) dominated the internal tide field. The vertical structure of the K_1 constituent presented a first-mode structure while the M_2 constituent seemed to exhibit a high-mode structure. Amplitude spectra analysis of the current data revealed differences in baroclinic current amplitudes between different water depths. Temporal variations in modal structures ware analyzed, based on the D_1 and D_2 baroclinic tides extracted from the baroclinic velocity field with band-pass filters. Analysis showed that the magnitude of the D_1 internal tide current was much larger than the D_2 current, and temporal variations in the modal structure of the D_1 internal tide occurred on an approximately fortnightly cycle. The EOF analyses revealed temporal transformation of multimodal structures for D_1 and D_2 internal tides. The enhancement of the D_1 internal tide was mainly due to the superposition of K_1 and O_1, according to the temporal variation of coherent kinetic energy.

Observed water current and transport through Qiongzhou Strait during August 2010

The velocity structure of the residual current across an entire section of the Qiongzhou Strait(QS) in summer is presented for the fi rst time. Shipboard Acoustic Doppler Current Profi le measurements, from the mid-region of the QS(110.18°E), were collected on 1–4 August 2010. The diurnal tidal currents had their maximum amplitudes between 4.24 and 20.24 m. Their amplitude along the major axis ranged from approximately 0.55 m/s in the middle part of the strait(20.15°N) to 0.84 m/s in the north part of the strait(20.20°N). Both anticlockwise and clockwise tidal current rotations exist in the QS. During the observation period(neap tide), a signifi cant westward residual current occupied almost the entire study section. Two velocity cores of westward current were observed at the northern part and near the deepest trough, although an eastward current appeared in the middle part of the transect. The deepest core was located near 62 m at 20.13°N, with a maximum velocity of-0.34 m/s. The shallower core was located at approximately 16 m at 20.20°N, with a maximum velocity of-0.33 m/s. The estimated total volume of water transported through the QS was-0.16 Sv. This value is an important boundary condition, applicable to numerical models studying coastal ocean circulation in the northwestern South China Sea.

Bridge Pressure Flow Scour at Clear Water Threshold Condition

Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally.The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional;all the measured scour profiles can be described by two similarity equations,where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth;the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge;the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge;and the maximum scour depth decreases with increas-ing sediment size,but increases with deck inundation.The theoretical analysis shows that:bridge scour can be divided into three cases,i.e.downstream unsubmerged,partially submerged,and totally submerged.For downstream unsubmerged flows,the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied;for partially and totally submerged flows,the equilibrium maximum scour depth can be described by a scour and an inundation similarity number,which has been confirmed by experiments with two decks and two sediment sizes.For application,a design and field evaluation procedure with examples is presented,including the maximum scour depth and scour profile.

VERTICAL PROFILES OF CHL-A AND PRIMARY PRODUCTIVITY IN THE MIDDLE CONTINENTAL SHELF AREA AND EDDY AREA OF THE EAST CHINA SEA

Vertical profiles of chl-a and primary productivity in the middle continental shelf area and eddy area of the East China Sea were studied using data from a cruise in the East China Sea in February to March, 1997 and a cruise in July, 1998. The results showed that chl-a vertical distribution closely related to in situ hydrological and nutrient conditions. Chla-a concentration ranged from 0.22 to 0.35 mg/m 3 and 0.93-1.09 mg/m 3 in the eddy area and in the middle continental shelf area, respectively. In both areas, chl-a concentrations in deep layers were slightly higher than those in shallow layers, but was of the same order of magnitude. In summer, when a thermocline existed in the water column, highest chl-a concentrations appeared at the base of the thermocline layers in both areas. In the eddy area, chl-a concentration maximized at 3l.743 mg/m 3, and averaged l.143 mg/m 3 below 30 m depth. In the middle continental shelf area, the highest chl-a concentration was 2.120 mg/m 3, the average was 1.168 mg/m 3. The primary productivity reached 1418.76 mgC/(m 2·d) in summer and 1360.69 mgC/(m 2·d) in winter. In the eddy area, the primary productivity was 787.50 mgC/(m 2·d) in summer and 159.04 mgC/(m 2·d) in winter. Vertical carbon sinking rate from the deep layer to the bottom in both areas is also discussed in this paper.

A potential stratotype for the regional lowermost stage of the continental Paleocene in China

Phanerozoic chronostratigraphic units can only be defined through their lower boundary stratotypes.The lowermost stage of the Paleocene of China,which mainly consists of terrestrial deposits,can only be defined through its lower boundary stratotype,i.e.the continental Cretaceous/Paleogene boundary stratotype.There is no section yet found which contains continuous terrestrial deposits and biostratigraphic records of the Cretaceous-Paleogene transition in Nanxiong,Guangdong and Jiayin,Heilongjiang,there is no evidence for establishing the continental stratotype of the Cretaceous/Paleogene boundary in either area.Therefore,both the"Shanghuan stage"and"Furaoan stage"are not good candidates for the lowermost stage of the Paleocene of China.From the viewpoint of charophytes,the outcrop section of the Dangyang,Hubei Province(Central China)contains the most continuous,abundant and diverse terrestrial biostratigraphic records of the Cretaceous-Paleogene transition,in particular the early Paleocene,known so far in the world.The biostratigraphic records of ostracods in the transition are also continuous,rich,and diverse.The Dangyang outcrop section is the only section known so far in China that is a possible candidate for a continental stratotype of the Cretaceous/Paleogene boundary in China and the section is the only potential section identified to date for establishing the regional lowermost stage of the Paleocene,Paleogene and Cenozoic in China or stratotype section for the stage.

AN ALGORITHM FOR MAXIMUM LIKELIHOOD ESTIMATES TO SEMI-PARAMETRIC REGRESSION MODEL WITH INTERVAL CENSORED DATA

In this paper we study the practical procedure for getting the maximumlikelihood estimates in a semi-parametric regression model with interval censored data.On the basis of the on previous theoretical results, we give the detailed algorithms when there are one or two covariates in the model.