基于地层孔隙结构的饱和度评价方法

油气勘探开发中阿尔奇公式是评价油气含量的经典模型,该模型适用于粒间孔隙的纯砂岩地层.然而实际油气评价中更多时候是以复杂孔隙结构地层为对象,复杂孔隙结构地层岩电关系却呈现出非阿尔奇特性,这意味着利用阿尔奇公式求取这类储层饱和度的可靠性大大降低.针对以上问题,采用变m、n指数和根据孔隙结构分类建立饱和度模型的方法一定程度上满足了此类地层饱和度评价的要求.但以上方法具有很强的区域性和经验性,没有从根本上解决复杂孔隙结构地层饱和度的准确评价问题.等效岩石组分模型将岩石等效为规则的圆柱体,由串联孔隙体积、并联孔隙体积和骨架体积构成,由许多这样大小不一的孔隙分量并联/串联构成整个岩石的导电体系,并引入孔隙结构系数表示不同孔隙的体积比,精确地描述了由复杂孔隙结构引起的非阿尔奇特性.其应用瓶颈是孔隙结构系数、饱和度因子等关键参数的确定方法.本文以等效岩石组分模型为基础。利用核磁测井资料和球管模型确定孔隙结构系数,根据孔隙结构寻优路径对地层进行分类,以岩电实验数据为基础利用阻尼最小二乘法分类确定模型参数,用等效岩石组分模型迭代计算地层饱和度,从而配套形成基于孔隙结构的饱和度评价方法.岩心实验数据分析和实际应用效果表明基于孔隙结构的饱和度模型与阿尔奇公式相比在复杂孔隙结构地层饱和度评价中具有优越性,在复杂孔隙结构地层含油气饱和度评价中具有良好的应用前景.     

Crustal velocity structure of the Shaowu-Nanping-Pingtan transect through Fujian from deep seismic sounding-tectonic implications

The Shaowu-Nanping-Pingtan deep seismic sounding profile is located in northern Fujian Province. High-quality seismic sounding data were acquired by five large explosive blasts received by 133 digital seismic instruments along the profile. Based on seismic facies analysis and travel-time picking on shot record sections, a model of the velocity structure of upper crust was developed by finite-difference tomography of the first breaks; the 2-D P-wave velocity structure and tectonic characteristics of the crust were interpreted further by fitting of waveforms and seismic travel times. The results show that the top of the crystalline basement is buried at depths of 2.0–4.0 km, with the deepest buried up to 4.0 km within the Fuzhou Basin. The Moho interface was found to be deeper in the west and shallower in the east(i.e., 30.0 km near the coast, increasing to 33.0 km northwestward). The lower crust on the east side of the Zhenghe-Haifeng Fault Zone has a smoothly varying gradient structure, whereas on the west side it has two distinct layers with a boundary between those layers at a depth of 23 km. Seismic velocities on the west side are generally lower than on the east side; a low velocity layer is observed with a lowest speed of 6.25 km/s at a depth of 22 km on the west side, which may consist of partially molten material. The Zhenghe-Haifeng Fault is a deep crustal fault, and should be a channel for deep material upwelling; it has a direct relationship with multiple stages of continental tectonic movements in Southern China and with multiple magmatic events that started in the Proterozoic and ended in the of late Tertiary in Fujian.     

地理国情信息支撑下的空间开发适宜性评价

作为主体功能区划的重要基础性工作,空间开发适宜性评价在协调解决城镇化进程中产生的空间开发失控和区域无序竞争等问题方面具有重要意义。本文利用地理国情成果数据、大比例尺基础测绘成果数据和行业专题资料及统计资料,结合GIS分析技术和层次分析方法,在构建适宜榆林市实际的空间开发适宜性评价体系的基础上,详细分析了榆林市空间开发的适宜性。结果表明,榆林市最适宜开发和较适宜开发的区域主要分布在榆林市的西北部地区,占榆林市总面积的18.4%;最不适宜开发和不适宜开发的地区主要分布在榆林市东南部地区,分别占榆林市总面积的39.86%和41.75%。究其原因,可能由于榆林市东南部多为山区、地势复杂,属于地质灾害频发地区,同时该地区人口数量大,导致人均可利用水资源较为匮乏,开发难度较大。     

世界砂岩型铀矿探明资源的分布及特征

最新核电发展规划显示未来我国对铀资源的需求很大。长久来看在继续加大国内勘探力度的同时,需尽快了解国外已探明铀资源尤其是砂岩型铀资源的分布,以更好地从全球视角完善我国的铀资源供应链。我国北方砂岩型铀矿大规模勘探始于本世纪初,起点较晚,在实际勘探和研究中也遇到较多难题及困惑。因此与全球同类型矿床的对比研究亟需展开,亦要求首先了解世界各国砂岩型铀矿的分布和基本特征。本文通过大量文献和最新勘探形势的调研整理,对比分析了近年来全球主要产铀国砂岩型铀矿资源量的变化,系统全面地编制了全新的全球和各国(或各大洲)已发现砂岩型铀矿床及其容矿层位分布图,总体可较精细地反映迄今全球各国已探明砂岩型铀矿分布面貌的现状,同时提炼了重点矿床的主要地质特征。最后总结出全球已发现砂岩型铀矿时空分布具有五大特征:(1)全球分布广泛但不均衡,跨欧亚存在东西向巨型铀矿带;(2)规模因地而异、(超)大型矿床较多;(3)平面分布与气候环境耦合明显;(4)容矿层时代跨度长、成矿时间相对较晚;(5)主要赋存于含油气或聚煤能源盆地中。本文提供了一份可以快速了解和全面把握全球砂岩型铀资源分布及其重要地质特征的材料,为科研人员提供可对比研究的国外矿床实例,同时也为我国企业"走出去"和"走向哪里"提供科学依据。     

Detrital apatite fission track analyses of the Subei basin: implications for basin-range structure of the northern Tibetan Plateau

The northern Tibetan Plateau has evolved a unique basin-range structure characterized by alternating elongated mountain ranges and basins over a history of multiple tectonic and fault activities. The Subei basin recorded evolution of this basin-range structure. In this study, detailed detrital apatite fission track (AFT) thermochronological studies in conjunction with previously documented data reveal provenance of the Subei basin, important information about the Indo-Eurasia collision, and two Miocene uplift and exhumation events of the northern Tibetan Plateau. Detrital AFT analyses combined with sedimentary evidences demonstrate that the Danghenanshan Mountains is the major provenance of the Subei basin. In addition, very old age peaks indicate that part sediments in the Subei basin are recycling sediments. Age peak populations of 70–44 Ma and 61–45 Ma from the lower and upper Baiyanghe formations record the tectono-thermal response to the Indo-Eurasia collision. Combined detrital AFT thermochronology, magnetostratigraphy and petrography results demonstrate the middle Miocene uplift and exhumation event initiated 14–12 Ma in the Subei basin, which may resulted from the Miocene east-west extension of the Tibetan Plateau. Another stronger uplift and exhumation event occurred in the late Miocene resulted from strengthened tectonic movement and climate. A much younger AFT grain age, breccia of diluvial facies and boulders of root fan subfacies record the late Miocene unroofing in the Danghenanshan Mountains.     

U–Pb dating of zircon and cassiterite from the Early Cretaceous Jiaojiguan iron-tin polymetallic deposit,implications for magmatism and metallogeny of the Tengchong area,western Yunnan,China

The newly discovered Jiaojiguan deposit, a medium-scale skarn iron-tin polymetallic deposit on the Sino-Burma boundary of Yunnan Province (SW China), is spatially associated with the biotite monzonitic granite. Here, we report new in situ zircon LA-MC-ICP-MS U–Pb ages, trace element and Hf isotope data from the granite, and U–Pb dating ages of cassiterite from the ore bodies. In this study, we obtain a weighted mean ²⁰⁶Pb/²³⁸U age of 124.1 ± 1.4 Ma for the zircon and a ²⁰⁷Pb/²⁰⁶Pb-²³⁸U/²⁰⁶Pb intercept age of 123.8 ± 2.2 Ma for the cassiterite. The granite crystallized during the Early Cretaceous, with zircons exhibiting εHf(t) values from ?5.8 to ?0.6 and two-stage Hf model ages (T_DM2) of 1.21–1.54 Ga. The close temporal and spatial links between pluton emplacement and ore-forming events suggest that magmatic-hydrothermal events were the key factors that triggered the genesis of the iron-tin polymetallic deposits in the area. Regional geochronological data show that tin mineralization took place three times during the Cretaceous–Palaeogene in the Tengchong block due to re-melting of the underlying supposed Proterozoic (1.5 ± 0.5 Ga) Sn-rich strata/materials. Compared with those in the Bangong–Nujiang metallogenic belt (BNMB), we propose that the Cretaceous iron-tin polymetallic mineralization events in Tengchong–Baoshan closely resemble those of the Bangong–Nujiang belt in northern Tibet, both of which have experienced similar tectono-magmatic-metallogenic histories since the Mesozoic.     

Petrogenesis of I-type granites from Yuqikapa granite pluton of the western Kunlun orogen: Deformation-driven filter-pressing differentiation

<正>1 Introduction The western Kunlun orogen,located in the northwest Tibet Plateau,and is a conjunction between the Pan-Asian and the Tethys tectonic domains.From north to south,the Western Kunlun orogen includes four     

A New Species of Cupressinocladus from the Lower Cretaceous of Guyang Basin, Inner Mongolia, China and Cluster Analysis

Cupressinocladus Seward is a fossil genus of conifers and conifer fossils with reproductive organs are very rare. In general, it is difficult to understand the natural affinities with other conifers. In this paper, a new species, Cupressinocladus guyangensis P.H. Jin et B.N. Sun sp. nov., is reported based on branches with immature female cones from the Lower Cretaceous Guyang Formation of the Guyang Basin in Inner Mongolia, northern China. The foliage shoots are decussate. Leaves are decussate, imbricate, scale-like, weakly dimorphic, and bear longitudinal glands on the abaxial view. Stomata complexes are haplocheilic, monocyclic, irregularly arranged, and spread along the leaf margin. Immature female cones are subglobose with 6–8 cone scales, and three subglobose ovules arranged in a row at the base of the cone scales. Moreover, we performed cluster analysis using a statistics and machine learning toolbox for 23 fossils and extant species based on 16 morphological characters. The result implies that the new species bears a close resemblance to the extant Cupressus funebris Endl. and might have nearest systematic affinities to it.     

新疆东天山多头山铁-铜矿区花岗岩类的年代学、地球化学、岩石成因及意义

多头山矿床是东天山阿奇山?雅满苏成矿带铁铜矿床的典型代表,矿床成因与区内岩浆岩有紧密联系。矿区出露的侵入岩主要有花岗斑岩、二长花岗岩、钾长花岗岩及英安玢岩。LA-ICP-MS锆石U-Pb年代学研究获得花岗斑岩、二长花岗岩及英安玢岩的年龄分别为316.3±8.1 Ma、318.3±3.0 Ma和197.2±3.5 Ma。花岗斑岩A/CNK介于0.82~1.01之间,显示偏铝质特征,为Ⅰ型花岗岩;同时样品富集大离子亲石元素Th、U、Pb,亏损高场强元素Nb、Ta、Ti,显示弧岩浆特征。钠质蚀变导致了花岗斑岩显示出富Na、贫K、Rb、Ca、Sr的特征。钠化花岗斑岩Nb/Ta为12.4~16.0,具有较高的ε_(Nd)(t)(5.76~6.24)值和较低的I_(Sr)值(0.70353~0.70532),与安第斯中生代岩基地球化学特征相似,结合样品中出现古老锆石的捕掳晶,表明其源区为新生的下地壳,混合有少量幔源物质,并伴随有地壳混染。二长花岗岩与钠化花岗斑岩具有相近的形成年龄和相似的地球化学特征,如Nb/Ta比值(14.2),亏损高场强元素、富集大离子亲石元素,同为准铝质(A/CNK=0.97)弧岩浆,暗示它们可能具有相似的源区。而早侏罗世的英安玢岩具有高Sr(552×10~(-6))含量和较高的Sr/Y(73.6)比值,显示出钙碱性埃达克岩的特征,同时样品具有较高的K_2O(3.27%)含量、Mg~#指数(55),表明其来源于拆沉下地壳的熔融并混有少量幔源岩浆。综合区域研究资料、年代学、地球化学及同位素特征,我们认为多头山所在的阿奇山?雅满苏成矿带可能是晚古生代洋壳向南俯冲至中天山地块之下形成的大陆边缘弧。     

对北京市矿山地质环境监测的几点认识

北京作为我国政治、文化、对外交流和科技创新中心,面临人口、资源巨大压力,地质环境承载力有限。因此,在京津冀协同发展的大背景下,应贯彻"五大发展理念",充分考虑北京世界城市建设对地质环境的需求,在加强基础性工作的基础上,正确应用相关技术标准。开展"区域+重要风险源(点)"相结合的监测网建设,有针对性开展监测。按城市地质工作的"两快、三高"要求,加强监测工作综合研究。发挥"首善之区"的示范作用,为"北京矿山生态环境监测"奠定基础。