WP和NAO对中国东南部冬季温度的协同影响   总被引：1，自引：0，他引：1       下载免费PDF全文

施春华  孙伟佳  郭栋 《大气科学学报》2021,44(3):394-404

利用NCEP/NCAR和ERA-Interim再分析资料,通过多元线性回归等分析方法,研究了西太平洋遥相关型(Western Pacific teleconnection, WP)和北大西洋涛动(North Atlantic Oscillation, NAO)的不同配置对中国东南部冬季气温的影响。结果表明:WP正位相年,中低纬太平洋被异常暖性高压控制,其局地作用使得中国东南部温度偏高;NAO正位相年,其遥相关作用通过南、北两支波列,分别调控南、北支槽系统,协同作用使得中国东南部30°N附近温度偏低。考虑这两种遥相关型的共同作用,当WP和NAO同位相时,两者作用部分抵消,中国东南部温度变化不显著;当WP正位相、NAO负位相时,两者同步的加热效应使得中国东南部显著暖异常;当WP负位相、NAO正位相时,两者同步的冷却效应使得中国东南部显著冷异常。  相似文献   

辽西基性岩床年代学、地球化学特征及地质意义     

陈井胜  李斌  刘淼  赵辰  汪岩 《地质论评》2023,69(Z1):134-136

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浅水三角洲物源、砂体构型与储层特征研究——以准噶尔盆地永进—莫西庄地区侏罗系三工河组二段为例     

冯怀伟  许淑梅  王金铎  张关龙  曾治平  任新成  修金磊  王千军 《地质论评》2023,69(4):2023040028-2023040028

针对准噶尔盆地腹部侏罗系三工河组物源、砂体构型及储层物性认识存在争议的问题,笔者等基于岩芯、录井、钻井等方面的资料,结合前人在准噶尔盆地周缘磷灰石及锆石年龄数据,运用沉积学、层序地层学、沉积盆地分析及储层沉积学的基本原理和方法对三工河组二段物源方向、远近和类型、沉积体系展布、砂体构型及储层物性之间的关系进行了系统的研究。研究表明,在敞流盆地快速抬升/缓慢沉降的构造背景下形成辫状河三角洲退积式沉积序列,在五级层序地层格架中,河道强冲刷叠置砂体见于第1、2砂组,三角洲退积,分支河道强烈冲刷,导致河道砂体叠置,微相类型单一,单砂体厚度向上变薄,砂体全区稳定分布,储集性较好。河道弱冲刷叠置砂体见于第3、5砂组,三角洲退积,分支河道冲刷不明显,形成河道“二元结构”,单砂体厚度向上变薄,粒度变细,储集性好;河口坝组合砂体见于第4砂组,在三角洲退积过程中,水下分流河道末端形成河口坝,总体岩性向上变细,砂体不连续,储集性好,远砂坝席状砂组合砂体见于第6、7砂组,砂体零星分布,储集性很差。在浅水、低可容纳空间、快速抬升/缓慢幕式沉降构造背景之下,浅水三角洲的物源的方向、远近及类型是影响沉积微相展布的关键因素,也是影响砂体构型及其储层物性的物质基础。  相似文献   

滇西丽江地区新生代富碱斑岩年代学、地球化学特征及其地质意义   总被引：2，自引：0，他引：2  

黄永高  罗改  张彤  熊昌利  贾小川  杨学俊 《现代地质》2018,32(1):28

滇西丽江地区新生代富碱斑岩位于滇西“三江”褶皱造山带与扬子板块西南缘结合部位,岩石类型多样,可分为碱性岩和碱性花岗岩,前者主要有正长斑岩、正长岩及粗面斑岩;后者主要包括花岗斑岩、二长花岗斑岩及石英二长斑岩。锆石LA ICP MS U Pb定年研究确定区内斑岩结晶年龄为346～371 Ma,侵位于始新世晚期。碱性岩石的SiO2含量为5454%～6770%,K2O＞Na2O,具有钾玄岩的特征;碱性花岗岩的SiO2含量为6716%～7066%,K2O＜Na2O,具有高钾钙碱性的特征。两类岩石都具有富碱(Na2O+K2O=703%～1170%)和准铝质—弱过铝质(A/CNK=064～115)的特征。富集轻稀土元素和大离子亲石元素(Sr、Ba、K、Pb等),相对亏损重稀土元素和高场强元素(Nb、Ta、Ti等),且具有高Sr、Sr/Y和La/Yb比值及低Y、Yb和镁值(Mg#＜05),表明区内斑岩兼具钾玄质岩石和埃达克质岩石的特征。综合研究认为,区内斑岩形成于印度－亚洲大陆碰撞造山的后碰撞阶段,其形成与减压熔融及幔源岩浆底侵促使增厚下地壳底部岩石发生部分熔融有关,是青藏高原东南缘构造转换带对主碰撞带造山作用过程的岩浆事件响应,进而分析确认本区具有斑岩-热液型金多金属矿床的找矿潜力,为深入认识丽江地区构造-岩浆-成矿作用提供了重要约束。  相似文献   

川西坳陷东坡沙溪庙组气藏成藏演化模式   总被引：1，自引：0，他引：1  

徐敏  刘建  林小云  熊山  牛斌莉 《现代地质》2018,32(5):953

川西坳陷东坡气藏主力产层为沙溪庙组,其圈闭类型以构造-岩性圈闭为主,多为致密砂岩储层,但断层发育,有效改善了储层物性,断砂匹配样式与构造演化对油气成藏过程有重要影响。基于前人已有的认识,通过沙溪庙组气藏成藏动力演化、气水分布特征及生烃期次分析,结合构造演化、成藏幕次等研究,认为沙溪庙组天然气成藏受构造古隆起、断砂配置、储层物性、构造演化影响,形成了“构造控向、断砂控运、储层控藏、演化控调”的成藏演化模式,同中存异,高庙子地区古构造的控制作用更为明显,而中江地区岩性控制作用占主导。沙溪庙组气藏间歇性充注具“燕山期三幕成藏,喜山期调整改造”的成藏特征,多期构造演化和较强的储层非均质性影响了含气饱和度,导致沙溪庙组气藏分布、气藏产能差异大。  相似文献   

湘西-黔东下寒武统清虚洞组藻灰岩沉积特征及其找矿意义          下载免费PDF全文

付胜云  张丰  曾健康  龙国华  邓蕾  程怡宁  李大江 《中国地质调查》2018,5(3):56-65

铅锌矿是湘西-黔东地区的优势矿种,资源丰富,开发历史悠久,找矿潜力巨大。综合分析前人有关湘西-黔东生物礁的资料,介绍了藻灰岩的沉积特征,并结合大量实际地质资料,对藻灰岩控矿进行了论述。结果表明: 成矿物质主要来源于藻类及碳酸盐泥对Pb²⁺、Zn²⁺离子的吸取,矿床成因属于沉积成岩矿床类型,兼有成岩期后矿床性质; 藻礁灰岩与不同岩性的接合部位及其附近等微地球化学障区,往往就是铅锌富矿体产出部位; 藻礁灰岩与礁间通道的薄层泥质白云质灰岩呈指状交叉接触处,也常有铅锌富矿体产出; 铅锌富矿体基本上产于清虚洞组灰岩段中,且明显受该段藻礁灰岩控制。为满足国内外对铅锌矿日益增长的消费需要,深入研究区内铅锌矿的地层岩相岩石控矿因素及其富集规律,指导该地区藻灰岩中铅锌矿找矿工作,具有重要的现实意义。  相似文献   

西秦岭温泉—中川一带金属矿床的成矿规律及找矿预测   总被引：1，自引：1，他引：0       下载免费PDF全文

刘彦良  高雅  罗维斌  季文中 《中国地质调查》2018,5(4):40-49

西秦岭温泉—中川一带实施的1:5万矿产地质调查项目,共圈定1:5万局部高磁异常33处,1:5万地球化学综合异常11处,发现矿点2处,矿化点5处,矿种有金、钼、铁、铜、铷等。通过分析研究区成矿地质条件、1:5万地球物理和地球化学综合异常特征、矿(化)点特征及分布规律等,阐明了该区成矿时空分布规律和矿产共生组合规律,划分成矿远景区9处,提交找矿靶区6处。对其中2处找矿靶区进行槽探验证的结果为: 关子镇幅玉杨观找矿靶区圈定了4条含铷矿化伟晶岩脉和多处铁矿化破碎蚀变带,具有形成伟晶岩型铷矿的潜力; 礼县幅李坝金矿床南侧百叶沟—河西沟找矿靶区圈定了14条蚀变破碎带,在矿化蚀变带内圈定了11条金矿(化)体,具有形成构造蚀变岩(微细粒浸染状)型金矿床的潜力。  相似文献   

The strain‐dependent spatial evolution of garnet in a high‐P ductile shear zone from the Western Gneiss Region (Norway): a synchrotron X‐ray microtomography study          下载免费PDF全文

A. Macente  F. Fusseis  L. Menegon  X. Xiao  T. John 《Journal of Metamorphic Geology》2017,35(5):565-583

Reaction and deformation microfabrics provide key information to understand the thermodynamic and kinetic controls of tectono‐metamorphic processes, however, they are usually analysed in two dimensions, omitting important information regarding the third spatial dimension. We applied synchrotron‐based X‐ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite–garnet eclogite in four dimensions, where the 4^th dimension is represented by the degree of strain. In the investigated samples, which cover a strain gradient into a shear zone from the Western Gneiss Region (Norway), we focused on the spatial transformation of garnet coronas into elongated garnet clusters with increasing strain. The microtomographic data allowed quantification of garnet volume, shape and spatial arrangement evolution with increasing strain. The microtomographic observations were combined with light microscope and backscatter electron images as well as electron microprobe (EMPA) and electron backscatter diffraction (EBSD) analysis to correlate mineral composition and orientation data with the X‐ray absorption signal of the same mineral grains. With increasing deformation, the garnet volume almost triples. In the low‐strain domain, garnet grains form a well interconnected large garnet aggregate that develops throughout the entire sample. We also observed that garnet coronas in the gabbros never completely encapsulate olivine grains. In the most highly deformed eclogites, the oblate shapes of garnet clusters reflect a deformational origin of the microfabrics. We interpret the aligned garnet aggregates to direct synkinematic fluid flow, and consequently influence the transport of dissolved chemical components. EBSD analyses reveal that garnet shows a near‐random crystal preferred orientation that testifies no evidence for crystal plasticity. There is, however evidence for minor fracturing, neo‐nucleation and overgrowth. Microprobe chemical analysis revealed that garnet compositions progressively equilibrate to eclogite facies, becoming more almandine‐rich. We interpret these observations as pointing to a mechanical disintegration of the garnet coronas during strain localization, and their rearrangement into individual garnet clusters through a combination of garnet coalescence and overgrowth while the rock was deforming.  相似文献   

Origin of sandplains in Western Australia: A review of the debate and some recent findings     

D. Newsome 《Australian Journal of Earth Sciences》2013,60(4):695-706

Views on the origin of sandplains in Western Australia remain controversial with debate focusing around three different models of formation. These are in situ, aeolian and in situ formation with local remobilisation by wind or colluvial transport. The only recent work on the subject to date espouses a dominantly aeolian origin. New work from a detailed study on the Victoria Plateau is described and demonstrates the applicability of utilising a range of evidence in understanding the origin of sandplains in Western Australia. Field investigations show a strong association of sandplain with sandstone and an absence of sand on non‐arenaceous geology in similar and adjacent topographic settings. Grainsize, mineral magnetic analysis and heavy‐mineral spectra show the Victoria Plateau to be a heterogeneous body of sand. These findings coupled with a lack of internal sedimentary structures are not consistent with an aeolian origin for the sandplain. Furthermore, scanning electron microscopy, grainsize and heavy minerals also demonstrate a clear link between bedrock and overlying sandplain. These data support the hypothesis that Western Australian sandplains are mostly the product of in situ weathering. Such findings question whether the origin of sandplains can be satisfactorily deduced without such a range of data.  相似文献   

Coral assemblages and reef growth in the Commonwealth of the Northern Mariana Islands (Western Pacific Ocean)     

Peter Houk  Robert Van Woesik 《Marine Ecology》2010,31(2):318-329

Reef development varies considerably around the high, raised‐limestone islands of the Commonwealth of the Northern Mariana Islands (CNMI). Here we examine the modern assemblages at 30 sites for coral composition, colony density, colony size, and fidelity. We defined four reef types and hypothesize the presence of environmentally driven ecological stasis, whereby the environment continuously selects for coral species membership, defines colony sizes, and over time creates the noted reef types. Our results show that constructional spur‐and‐groove reefs supported significantly larger coral‐colony sizes and higher coral species richness compared with high‐relief interstitial framework, low‐relief incipient, and non‐constructional coral assemblages. Non‐constructional reefs supported much smaller coral colony sizes, despite similar population densities, and were consistently found in association with high wave exposure. The distinct coral assemblages found on interstitial framework and low‐relief incipient reefs were not affiliated with any wave exposure regime, but were located adjacent to large watersheds and on islands with unique geological history. These assemblages were nested within the spur‐and‐groove species pool. Overall, modern coral cover was well predicted by bathymetric slope and watershed size, while species richness was additively influenced by two proxies of pollution, suggesting the latter is better suited for establishing management targets. In contrast with previous studies that suggested modern assemblages were biologically controlled in the CNMI, we show reef assemblages and reef development are highly influenced by long‐term environmental forcing.  相似文献