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1.
A well‐constrained plate deformation model may lead to an improved understanding of sedimentary basin formation and the connection between subduction history and over‐riding plate deformation. Building quantitative models of basin kinematics and deformation remains challenging often due to the lack of comprehensive constraints. The Bohai Bay Basin (BBB) is an important manifestation of the destruction of the North China Craton, and records the plate kinematic history of East Asia during the Cenozoic. Although a number of interpretations of the formation of the BBB have been proposed, few quantitative basin reconstruction models have been built to test and refine previous ideas. Here, we developed a quantitative deformation reconstruction of the BBB constrained with balanced cross‐sections and structural, stratigraphic and depositional age data. Our reconstruction suggests that the basin formation process was composed of three main stages: Paleocene‐early Eocene (65–42 Ma) extension initiation, middle Eocene‐early Oligocene (42–32.8 Ma) extension climax and post‐Oligocene (32.8–0 Ma) post‐extensional subsidence. The deformation of the BBB is spatially heterogeneous, and its velocity directions rotated clockwise during the basin formation process. The reconstruction supports the interpretation that the BBB formed via strike‐slip faulting and orthogonal extension and that the basin is classified as a composite extensional‐transtensional basin. We argue that the clockwise rotation of the basin velocity field was driven by the counter‐clockwise rotation in the direction of Pacific Plate subduction. The kinematics of the BBB imply that the Pacific Plate may have been sufficiently coupled to the over‐riding East Asian Plate during the critical period of Pacific Plate reorganization. The new reconstruction provides a quantitative basis for studies of deformation processes not only in the vicinity of the BBB, but also more broadly throughout East Asia.  相似文献   
2.
The Bear Brook Watershed in Maine (BBWM) is a long-term research site established to study the response of forest ecosystem function to environmental disturbances of chronic acidic deposition and ecosystem nitrogen enrichment. Starting in 1989, the West Bear (treated) watershed received bimonthly applications of ammonium sulfate [(NH4)2SO4] fertilizer from above the canopy, whereas East Bear (reference) received ambient deposition. The treatments were stopped in 2016, marking the beginning of the recovery phase. Research at the site has focused on soils, streams, and vegetation. Here, we describe data collected over three decades at the BBWM—input and stream output nutrient fluxes, quantitative soil pits and soil chemistry, and soil temperature and moisture.  相似文献   
3.
陈进  毛先成  邓浩 《地球学报》2020,41(2):179-191
大尹格庄金矿是胶西北招平断裂带中段的大型金矿床,但随着逐渐的开采其保有资源量不断下降,急需在矿床的深边部区域开展接续资源找矿工作。本文以大尹格庄金矿为研究对象,以区域成矿理论和找矿勘查模型为指导,利用三维地质建模技术构建了相关地质体的三维模型,在此基础上,采用定量化的方法提取地质体与成矿相关的控矿因素指标和矿化指标,并建立了三维定量成矿预测模型,并应用该模型圈定了3个找矿靶区。研究表明,该方法能够适用于大中型矿山的深边部找矿工作,其三维及定量化的预测结果能够为后续的勘探及开采工作提供重要参考。  相似文献   
4.
利用2017年3月8日到4月8日鸭梨花芽发育观测照片对照同期气象资料,分析鸭梨花芽萌发后气象要素对鸭梨花芽发育物候期的影响。结果表明:气温和地温自始至终主导鸭梨花芽发育进度,开绽、露蕾、露冠和始花关键物候期需要满足较好的天气条件和适宜积温,物候期转变时都有10℃以上的温暖天气相对应;风速、日照、降雨等气象要素对鸭梨花芽发育影响程度,在花芽萌发到开绽、开绽到始花和花期三个阶段,其影响程度、利弊各不相同。本文试图通过对鸭梨花芽发育过程各生育期气象影响因子初步分析,为探讨符合鸭梨物候发育规律的花期预报方法,提供新的研究思路。  相似文献   
5.
断陷湖盆缓坡河流成因砂体是重要的油气储集单元。根据岩心观察、钻井岩/电特征并结合地震沉积学方法,分析断陷湖盆缓坡河流沉积体系和砂体时空分布特征,能为油气精细勘探提供可靠的依据。研究表明,霸县凹陷文安斜坡中部东营组三段周期性地发育4条呈NE-SW辫-曲复合型河流沉积,由河道沉积、砂坝沉积和泛滥平原沉积3种亚相以及辫状河道、曲流河道、砂质河道砂坝、泥质河道砂坝、决口扇和泛滥平原泥6种微相构成。河流展布方向与正北夹角(α)为40°~65°,河道视宽度(l)为1.47~2.64 km,主河道的视宽度(w)为0.03~0.58 km,河道带测量厚度(H)为16.0~52.0 m,主河道测量厚度(D)为8.0~23.0 m,主河道钻井解释厚度(d)为1~16.5 m,平均厚度6.5 m。断陷盆地断-坳转换期缓坡河流相沉积受控于盆地构造、气候、物源、沉积物压实及流速等多因素。边界断层差异性活动导致的盆地不均衡沉降是缓坡带河流相类型及砂体空间分布的主控因素。气候周期性变化通过流量控制了河型,调整和改造早期河道沉积物,决定了微相和砂体组合。斜坡中外带是粗粒沉积物主要卸载区,河道及河道砂坝等优势储集砂体呈条带状连片分布,斜坡内带形成的厚层泥岩限制油气垂向运移和侧向充注。斜坡中外带被油源断层切割,在油气运移路径上受晚期断层切割的厚层河道及河道砂坝是岩性-构造油气藏勘探的潜力区域。  相似文献   
6.
This article borrows a statistical method from physical geography—topographical prominence—to suggest a new technique for measuring the relative significance or rank of population centers. Unlike raw population measures, prominence gives consideration to both the spatial intensity of concentrated population areas as well as the spatial dependence or independence of neighboring settlement clusters in relation to one another. We explain how to apply the topographic prominence calculation method to gridded population data and examine its practical utility through case studies of several U.S. states. We then discuss some ways in which parametric choices about point-to-surface transformations can result in considerably different outcomes and offer further suggestions for conceptualizing and measuring population center significance.  相似文献   
7.
以Q型系统聚类分析(以组内连接为聚类方法,相关性为计算模型)和判别分析交替使用的方法,对甘肃省西秦岭地区花岗岩样本中的11个氧化物测试数据进行定量处理,构建起"甘肃省西秦岭地区花岗岩(氧化物)定量分类系列模型",将西秦岭地区花岗岩分为3大类共8小类。分类结果偏重于找矿分类,依据其与西秦岭地区铜矿、铅锌矿、金矿等依据空间关系(距离岩体3 km以内),寻找"成矿相关岩体",确定找矿靶区。  相似文献   
8.
An effective strategy of seismic retrofitting consists of installing nonlinear viscous dampers between the existing building, with insufficient lateral resistance, and some auxiliary towers, specially designed and erected as reaction structures. This allows improving the seismic performance of the existing building without any major alteration to its structural and nonstructural elements, which makes this approach particularly appealing for buildings with heritage value. In this paper, the nonlinear governing equations of the coupled lateral‐torsional seismic motion are derived from first principles for the general case of a multistory building connected at various locations in plan and in elevation to an arbitrary number of multistory towers. This formulation is then used to assess the performance of the proposed retrofitting strategy for a real case study, namely, a 5‐story student hall of residence in the city of Messina, Italy. The results of extensive time‐history analyses highlight the key design considerations associated with the stiffness of the reaction towers and the mechanical parameters of the nonlinear viscous dampers, confirming the validity of this approach.  相似文献   
9.
As a part of the north-south seismic zone in China, a lot of M6.0-7.2 earthquakes have occurred in the margin faults of the Minshan block in history. This work attempted to characterize the geometry and activity of the north section of the Minjiang fault in this region based on high-resolution satellite images, geologic and geomorphic investigations, micro-geomorphic surveys, and trench excavation. The results show left-lateral-slip and Holocene activity of this structure. Along it, the offset landform has a continuous linearity on Ⅱ terraces near the Chuanpan village. The vertical height of the fault scarp measures 3.1 meters, which is almost the same as the accumulative horizontal displacement of the gully. The accumulative horizontal shortening due to faulting is 3.0 meters. Calculation using the model of displacement-dependent characteristic earthquakes shows both the vertical and horizontal co-seismic displacements and the horizontal shortening amount are about 1.0 meter. While strata dating suggests that the vertical and horizontal slip rates are all about 0.7-0.9mm/a, and the horizontal shortening rate is approximately 1.0-1.1mm/a. The excavated trench, perpendicular to the fault trace, reveals low-angle thrust dipping in 260åt 29°. From the relationship of the fault, colluvial wedge and stratigraphy ages, three palaeoseismic events are identified from youngest to oldest at 0-295a BP, 1 405-1 565a BP, and 2 750-2 875a BP, respectively, with recurrence intervals 1 110-1 565 years and elapsed time about 0-295 years。According to the relationship between magnitude and active parameters, it is considered that the northern segment of the Minjiang fault is capable of generating M7 or greater earthquakes. Now it is in the process of stress accumulation, having a certain seismic risk.  相似文献   
10.
Topographic effect study is a very important research topic in seismology, seismic engineering,earthquake engineering, engineering earthquake construction and engineering seismology. This paper focuses on its present development status. Post-earthquake investigation has found that the existence of topography caused more serious earthquake damage. The actual seismographs also recorded the topographic amplification effect of 6 to 7 times and even more than 10 times. Numerical simulation is an important technique to study topographic effect, which complements the lack of observed records. However researches on 3-D topographic effect are not enough and need to be studied deeper. To find the main influence factors and the quantitative relationship between topography and ground motion are required very urgently. Obviously the achievements not only can be applied in the earthquake resistant design, but also can provide the quantitative pre-earthquake disaster prediction and quantitative post-earthquake disaster evaluation.  相似文献   
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