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1.
中高山区土壤成土母质理化特征及主控因素初探——以西昌市为例 总被引：1，自引：1，他引：0
为探讨中高山区土壤及成土母质理化特征及其控制因素,本文以四川省西昌市为例,系统性总结了该地区的地质建造背景,并在基于地质建造背景划分的成土母质类型基础上,讨论了成土母质、土壤的物理化学性质、土壤含水率、pH值、高程等之间的关系,通过对不同成土母质发育的同种土壤的数据分析及营养元素含量评价,我们认为地质建造背景直接制约了成土母质及土壤的物理化学性质,营养元素在成土母质—土壤之间的迁移存在继承性。本文研究成果为中高山区土壤类型和成土母质之间的关系以及成土母质单元划分方案提供理论依据。 相似文献
2.
根据生态环境地质调查结果表明 ,各类型土壤的形成及分布特征与地形地貌地质构造条件密切相关 ;在侵蚀度相同时 ,成土母质决定土壤植物营养元素的富集程度 ;母质与微地形地貌共同影响土壤营养元素组合的地域分布 ;新构造运动影响土壤植物营养元素的流失强度和土壤退化特征 ;不同的地质环境和农业生态特征决定低产田的障碍因素和治理对策 相似文献
3.
基于地统计学及GIS的西昌地区中生代红层区紫色土营养元素空间变异性及影响因素研究 总被引：1，自引：0，他引：1
基于大凉山生态地质调查获取的48个岩石—土壤剖面数据,通过地质建造单元调查、土壤类型划分及元素地球化学测试,采用地统计学方法和GIS技术对西昌地区中生代泥质岩类地质建造区紫色土中4种微量营养元素Cu、Zn、Mo和B的空间变异及分布特征展开研究,并讨论了不同影响因素下4种营养元素的含量特征。结果表明：(1)4种营养元素整体属于中等强度变异,高斯模型和指数模型可以很好地反映研究区4种营养元素的空间变异特征;(2)4种营养元素整体处于丰富等级,Cu、Zn和B营养元素含量高值区主要集中分布在西昌地区东北—西南带状区域内,Mo元素含量在全区范围内含量较高;(3)不同地质条件（海拔高度、地层、岩性、地质时代）和不同植被覆盖类型共同制约着Cu、Zn、Mo和B植物生长所需的营养元素含量及空间分布特征。此外,紫色土剖面土壤层4种营养元素的含量特征还受到一定的人类活动影响。研究结果可以对当地农林业发展及土地资源的合理利用提供一定参考。 相似文献
4.
为适应生态地质调查和评价工作对成土母质研究的要求,以四川大凉山区为例,提出基于地质建造的成土母质分类方案,即以地质构造演化和地质建造环境为依据,结合残坡积物的成因类型对成土母质进行分类。大凉山区的成土母质可划分为第四纪冲洪积物、新近纪—第四纪砂泥岩类残坡积物、侏罗纪—白垩纪泥质岩类残坡积物、三叠纪砂泥岩类残坡积物、中生代中酸性岩类残坡积物、二叠纪基性—超基性岩类残坡积物、震旦纪—三叠纪砂泥岩类残坡积物、震旦纪—三叠纪碳酸盐岩类残坡积物、元古宙中酸性岩类残坡积物、元古宙火山碎屑岩类残坡积物、元古宙基性—超基性岩类残坡积物、元古宙变质岩类残坡积物等12类。研究表明,大凉山区成土母质和土壤存在差异性,但同一成土母质上的不同土壤类型具有一定相似的地球化学特征,不同成土母质形成的同一种土壤类型存在较大的地球化学差异。因此,基于地质建造的成土母质分类方案既能有效反映不同构造背景和成岩环境下的成土母质差异,又能有效表征成土母质与其上土壤的内在联系。 相似文献
5.
基于地质建造的土壤地质调查及应用前景分析——以大凉山区西昌市为例 总被引：1，自引：1，他引：0
为探索适合中—高山区的土壤地质调查方法,选择兼具高寒山区、干热峡谷和中山宽谷盆地等不同地貌单元,以及沉积建造、岩浆建造和变质建造等不同地质建造类型的大凉山区西昌市进行试点研究。本次工作基于地质建造,将西昌市成土母质划分为7大类14个类,土壤地质单元分为31个类,并探讨了他们的互馈机制。研究认为,地质建造是土壤的物质基础,大体控制了土壤的平面分带,而海拔等地理因素则控制土壤的垂向分带。本项研究可为地方政府的规划布局提供数据支持和科学依据,也为高山区的土壤地质调查和生态地质调查提供了思路与范例。 相似文献
6.
生态地质调查以区域地质调查成果为基础，查明调查区生态地质现状和主要生态地质问题，研究生态环境与地质条件之间的联系，并开展生态地质综合评价。笔者利用在大凉山区和三峡库区生态地质调查的探索经验，总结了西南山区生态地质调查与评价思路和技术方法，主要取得以下认识：(1)地质条件是生态系统的物质基础和孕育环境，地质条件通过制约土壤、水文、地形地貌、动力作用、地质灾害等生态地质条件，而制约生态系统质量和生态环境发展差异。(2)西南山区成土母质主要是下伏基岩原地风化或风化后近距离迁移形成的，存在明显的岩石-土壤-植被物质传导链条，地质条件是制约该地区生态环境质量的重要因素。(3)对地质建造和地质构造等地质条件的分析和研究，是在该地区进行生态地质调查的基础。(4)提出了西南山区生态地质调查的目的任务、工作思路、工作内容、技术路线和主要技术方法。该成果可为西南山区开展生态地质调查提供借鉴案例，同时对生态地质学科的建设和全国生态地质调查方法体系的建立也具有一定支撑作用。 相似文献
7.
土壤中有益微量元素的含量受多种因素影响。根据不同地质背景特征,安徽省潜山县划分为7类成土母质。该文对不同成土母质、不同土壤类型进行了土地质量地球化学调查, 8 116件土壤样统计分析结果显示:潮土的Cu和Zn平均含量明显高于其他土壤类型,棕壤的Mo和Se平均含量也明显高于其他土壤类型;在相同土壤类型,不同成土母质之间微量有益元素含量的差异性较大;在不同土壤类型,相同成土母质体内有益微量元素的含量趋于一致。原位风化情况下,成土母质来源于地质背景区基岩风化,土壤中有益微量元素的丰缺取决于基岩类型;非原位风化情况下,成土母质如河流冲积物类母质,形成的各种类型土壤元素含量变化较大。部分土壤类型如潮土和棕壤中微量元素含量特征由土壤类型决定。以地质背景为基础的成土母质与土壤类型综合影响潜山县土壤有益微量元素的含量特征。 相似文献
8.
为研究祁连山地区地球关键带过程与生态自然修复的关系,对该地区进行了生态单元划分和土壤全剖面测量。通过野外路线调查、剖面测量,结合遥感影像,从构造环境、成土母岩、地貌、土壤、植被、主要生态问题及生态功能等,将研究区划分出4个三级生态地质单元,其中Ⅶ3-e生态地质单元进一步划分出2个四级生态地质单元。通过对全剖面土壤连续采集的39件土壤样品的主、微量元素分析,发现研究区关键带成土过程中不同元素淋失程度不同:Ⅶ3-e-2生态地质单元的砾岩风化成土过程Ⅶ3-e-2生态地质单元的砂岩风化成土过程Ⅶ3-e-1生态地质单元的闪长岩风化成土过程Ⅴ3-i生态地质单元内的砂岩风化成土过程;土壤中有益元素的迁移和富集与气候、植被类型关系密切,有益元素含量普遍高于背景值。研究表明,随着近年来研究区气候暖湿化趋势持续增强,降雨量增加,加之祁连山矿山环境治理工作和祁连山国家级自然保护区生态移民搬迁工作的强力推进,祁连山地区生态问题可以实现自然修复。 相似文献
9.
基于安徽省江淮流域多目标区域地球化学调查数据资料,统计获得了表层和深层土壤地球化学基准值、背景值及相应的地球化学参数,为研究区生态环境评价及相关学科研究提供了基础。研究表明,成土母质类型对土壤元素地球化学基准值影响显著,表层土壤化学组成表现出既对深层土壤具有一定的继承性,又在表生作用下发生某些变化:表层土壤中迁移活动性强的元素和人为扰动污染的元素明显不同于深层土壤;随着地理空间位置的变化,同类成土母质形成环境、成因来源的差异导致其化学组成的空间变异,造成不同地区同类成土母质地球化学基准值有所不同。因此,土壤地球化学基准值研究应更多地考虑地质背景、物质来源等因素的影响。 相似文献
10.
土壤地质单位是地学工作者根据地质资料、结合成土特征提出的一种新型土壤分类方法,其实质就是在充分考虑气候、生物、地形、时间等成土因素的同时,抓住母岩-母质-土壤三者之间的成生联系,找出成土母岩岩性、矿物成分、结构构造、地球化学特征对土壤结构、质地、厚度、微量营养元素的制约关系,为农业区划和农业种植结构调整提供科学的依据.笔者据浙江省农业地质背景调查项目实践,在从地学角度对浙江省成土母质进行分类的基础上,结合土壤亚类建立了土壤地质单位,并提出研究内容和研究方法. 相似文献
11.
白露山岩体是苏北地区重要的金刚石含矿岩体。通过研究该岩体中的铬铁矿化学成分,探讨其成因及金刚石的含矿性,进一步分析金刚石的成矿潜力。白露山岩体中的铬铁矿具有高Cr、低Al、高Mg的特征,属于镁铬铁矿,是深部地幔橄榄岩结晶而成的,不是岩体本身的结晶产物,可能来源于岩体中的深源捕虏体。铬铁矿的结晶温度为1 253~1 354 ℃,与金刚石的形成温度(1 150~1 400 ℃)相近,二者关系密切。铬铁矿化学成分与山东、辽宁含矿金伯利岩中铬铁矿的化学成分较相似,多数属于S4组和S6组铬铁矿,少数属于S1组和S2组铬铁矿,其中S1组和S2组铬铁矿是含矿岩体的标型矿物。白露山岩体具有良好的金刚石成矿潜力和找矿前景。 相似文献
12.
草山花岗岩为八里沟金矿成矿岩体。笔者利用电子探针对草山花岗岩体中黑云母化学成分进行研究,以此来探讨岩浆成因及成矿潜力。研究表明草山花岗岩中的黑云母为岩浆成因的镁质黑云母,具有富Al、K、Mg、Ti,低Na、Ca的特征。以22个氧原子为基础计算了黑云母的阳离子数及相关参数,其全铝(~TAl)、镁质率(Mg~#)较高。利用黑云母化学成分对岩体固结的温度、压力、侵位深度及氧逸度进行了估算。岩石固结时的温度为750℃~780℃,固结压力范围为131.77~143.89 MPa,侵位深度为5.0~5.4 km,氧逸度f(O_2)=10~(-13)~10~(-14);由此得出其为中等深度、高温、高氧逸度岩体。黑云母化学成分特征暗示岩石为I型花岗岩,岩浆是在太平洋板块向华北板块俯冲、地壳加厚的背景下,由壳、幔物质混熔而形成。草山花岗岩固结时温度、氧逸度较高,有利于Au进入岩浆期后成矿流体中,表明八里沟金矿潜力较大。 相似文献
13.
The Yamato diogenite, Y-74013, shows a high degree of textural equilibrium with the apparent crystallization sequence: troilite and metal → orthopyroxene → plagioclase. The position of the large chromite crystals in this sequence is unclear. Except chromite, all other minerals have composition similar to common orthopyroxene achondrites. The chromite is more magnesian than in common diogenites, strongly zoned and, on the whole, intermediate in composition between chromites of diogenites and pallasites. Texture, mineral composition data and an equilibrium thermodynamic analysis of the mineral association strongly indicate that the chromite crystallized earlier than the silicates at a much higher temperature (possibly above 1100°C) and rapidly grew in a medium which was progressively enriched in Mg, Al and Ti. But the chromite failed to reach chemical equilibrium, even at its outermost rim, with the orthopyroxene. The calculated equilibrium log fO2 of the Yamato diogenite, ?20·21 to ?11·08 for temperatures between 880°C and 1500°C is well within the normal oxygen fugacity range of pyroxene achondrites. 相似文献
14.
元古代蛇绿岩及铬铁矿 总被引：2，自引：1，他引：1
本文总结了国外典型元古代蛇绿岩的岩石组合、野外产状、地球化学资料以及成矿特征,并与显生宙蛇绿岩进行了对比,继而探讨元古代板块构造演化和铬铁矿成因。资料表明,早元古代和中-新元古代均有蛇绿岩的存在,但前者较少,仅见于Canadian地盾的Cape Smith Belt中的Prutuniq蛇绿岩(2. 05～2. 0Ga)和芬兰Fennoscandian地盾的Outokumpu和Jormua蛇绿岩(时代为1. 97～1. 96Ga),而中-新元古代的蛇绿岩则见于世界许多地区,如埃及东部沙漠区(～750Ma)和非洲东北部地区(ca.900～800Ma)等。与显生宙蛇绿岩相比,这些老蛇绿岩具如下特征:(1)它们均为被肢解的蛇绿岩,大多与"弧火山岩"和(或)混杂岩伴生,经历不同程度的变形和变质(具绿片岩相-角闪岩相组合);(2)岩石组合大多较齐全,壳层组合发育,以镁铁-超镁铁岩(堆晶岩)、辉长岩、镁铁质席状岩床(墙)杂岩、火山岩为代表;层状镁铁-超镁铁岩的韵律层以及矿物的隐晶变化等均提示了岩浆多期次活动及开放岩浆房的特征;(3)元古代蛇绿岩中既有高铝型铬铁矿,也有高铬型铬铁矿,且主要寄主于纯橄岩(或蛇纹岩)中;高铝型和高铬型直接受控于熔体的熔融程度及含水流体的参与,反映了铬铁矿形成于俯冲带演化的不同阶段;铬铁矿规模均较小,且均以低TiO 2为特征,均为岩浆分异作用的产物,明显区别于显生宙熔融残余成因的豆荚状铬铁矿;(4)元古代蛇绿岩常伴有硫化物Cu-Co-Zn-Au矿,且铬铁矿含Zn较高(Zn=0. 11%～0. 18%)(如芬兰Outokumpu蛇绿岩);橄榄岩及铬铁矿中常含较高的MnO (高达1. 79%,如埃及东部的Wizer蛇绿岩);(5)元古代蛇绿岩具多种成因:主要为俯冲带成因(如埃及蛇绿岩、北东非蛇绿岩、芬兰Outokumpu蛇绿岩),少量为洋中脊成因(加拿大Purtuniq蛇绿岩)及裂谷成因(芬兰Jormua蛇绿岩)等。 相似文献
15.
The regional distribution and chemical composition of massive and disseminated chromitites through a Platreef sequence and
along a strike distance of over ∼20 km were investigated to correlate them both within the framework of the northern limb
and to the eastern and western limbs of the Bushveld Complex. The chromitite layers and seams of the Platreef form two main
chromite-bearing zones: the Upper Chromitite that occurs as two to three discontinuous seams in feldspathic pyroxenite at
approximately 20 m below the Platreef top contact and the Lower Chromitite that is composed of multiple seams in feldspathic
harzburgite, pyroxenite and norite close to the bottom contact of the Platreef with footwall. Electron micro-probe analyses
reveal that the chemical composition of chromite depends on the host rock type. Norite and pyroxenite host chromite with the
highest Cr2O3 content while harzburgite-hosted chromites are Cr and Mg poor. The wide range in chromite compositions is explained by the
influence of late-magmatic processes including post-cumulus growth and re-equilibration, interaction with fluid- and sulphide-saturated
magmatic liquid and contact metamorphism. Each of these processes is characterised by its own distinct geochemical signature,
but generally they lead to a decrease in Mg and Al and an increase in both di- and tri-valent Fe in the chromite. The occurrence
of chromitite locally on the different distance from the contact between the upper Platreef sills and the overlying Main Zone
magma suggests erosion of the upper Platreef by the Main Zone as it was emplaced. The localisation of chromitites supports
an independent development of the northern limb during the Critical Zone emplacement although the chemical composition of
chromite and co-existing silicates from ultramafic rocks suggest a Critical Zone affinity with the eastern and western limbs
of the Bushveld Complex. 相似文献
16.
为了研究瓦房店和蒙阴矿区铬铁矿成分与金伯利岩含矿性关系,对2个矿区的铬铁矿进行了系统的采样,利用电子探针波谱技术测定了不同品位含矿岩管金伯利岩中的100个铬铁矿微区化学成分.分析结果表明：不同世代的铬铁矿的化学成分不同,主要差别在铬和铝2个元素上.如果用Cr/（Cr+Al）=Cr'来表示铬铁矿与金伯利岩含矿性的关系,那么金刚石包裹体中铬铁矿的Cr'值为89.75%;富矿岩体中的第一世代铬铁矿Cr'值为89.47%;中等含矿岩体中第一世代铬铁矿Cr'值为86.83%,第二世代铬铁矿Cr'值为82.74%;贫矿的岩体中第三世代铬铁矿Cr'值为68.98%.金伯利岩岩体中含金刚石由富到贫,对应岩石中铬铁矿Cr'值依次变低,具有明显的找矿矿物学特征. 相似文献
17.
应用统计法作金刚石找矿中铬铁矿的属性判别 总被引：1，自引：0，他引：1
根据金伯利岩、钾镁煌斑岩、金刚石包体及其它岩石中铬铁矿电子探针分析成果的统计,发现铬铁矿随着Cr_2O_3含量的降低,其它组分具有四种演化趋势。一般一种岩石中的铬铁矿只有一种演化趋势,唯有金伯利岩、钾镁煌斑岩中有两种演化趋势共存。根据统计资料,采用Cr_2O_3-TiO_2、Cr_2O_3-Al_2O_3和MgO含量,建立了金伯利岩、钾镁煌斑岩中铬铁矿属性判别图,图中三个区间可提供岩石类型、含矿性及保存性三种信息。 相似文献
18.
Prospecting for kimberlites and related rocks in till-covered terrains requires a methodology for recovering a few small grains within tens of kilograms samples, necessitating 1 ppb sensitivity or better. As part of reconnaissance survey for the kimberlite indicator minerals, i.e. pyrope garnet, picroilmenite, chromite and chromian diopside, the Geological Survey of Finland (GTK) developed such a system by significantly modifying and augmenting a 3″ Knelson Concentrator that accomplishes nearly complete recovery of moderately heavy minerals (>0.25 mm) from till samples.Diamondiferous kimberlites occur in the eastern Finland around the Kaavi–Kuopio and Kuhmo areas and much of the rest of the Karelian craton remains prospective based on the empirical evidence necessary for diamond preservation: thick (>200 km) lithospheric mantle, low heat flow and Archaean age rocks. A target area in Lapland, 20×50 km in size, was selected for a pilot study to test extraction of chromite for the (1) discrimination of regionally and locally derived populations, and (2) recognition of possible kimberlitic/lamproitic chromites. Area selection was based on the regional occurrence of a variety of mantle-derived rocks, the recovery of a chromian pyrope grain from till in 1996 and most importantly, the well-established Quaternary stratigraphy in the region. The sample material consisted of sixty-two 80-kg excavator and 40-kg shovel samples. Approximately 1000 chromite grains, almost exclusively 0.25–0.5 mm in diameter, were recovered and analysed by electron microprobe.Tills in the sampling area proved to contain at least two compositional populations of chromite. The first is present in almost every sample and is apparently derived from layered mafic intrusions distal to and up-ice from the study area. The second population consists of chromites with low Ti, high Cr and Mg similar to inclusions in diamond. It is present in approximately one third of the samples, concentrated in a couple of clusters within the target area and is therefore considered to be of more local derivation. Since no high-Ti, high-Cr chromites diagnostic for kimberlites and lamproites were present in the samples, the source for the low-Ti, high-Cr, high-Mg chromite grains remains uncertain, but is probably not kimberlitic. Although this apparently is a negative outcome for diamond exploration in the target area, the main goal of the study was realised by showing the applicability of the system to heavy mineral separation from Quaternary glacial deposits. 相似文献
19.
A Metamorphosed, Early Archaean Chromitite from West Greenland: Implications for the Genesis of Archaean Anorthositic Chromitites 总被引：2，自引：0，他引：2
An early Archaean (>3·81 Ga) chromitite–ultramaficlayered body from the Ujaragssuit nunât area, west Greenland,may represent the Earth’s oldest chromitite. The layeredbody occurs as a large xenolith (800 m x 100 m) entrained withintonalitic gneisses and preserves primary igneous layering andtextures. New Re–Os and Pb–Pb isotope results supportthe view that it has been metamorphosed twice, in the earlyand late Archaean at 3·75 Ga and 2·8 Ga. Mineralchemistry and textures indicate that the chromite compositionspreserve two different evolutionary trends. There is a mainmagmatic trend in which Cr/(Cr + Al) ratios remain relativelyconstant but in which there is strong enrichment in Fe3+, Fe2+and Ti with progressive differentiation. This trend is a compositeof magmatic-liquidus, magmatic-cooling and subsolidus re-equilibrationprocesses. A second trend is defined by chromites from harzburgitesin the upper part of the layered body. These chromites showmagmatic replacement textures in which Fe-rich chromites arealtered to aluminous chromites. Chromites showing magmatic replacementtextures are thought to have formed by reaction with a late,interstitial melt during the solidification of the layered body.The close association between the Fe3+–Cr-chromites ofthe main trend and Al-rich chromites of the type found in otherArchaean megacrystic anorthosites suggest a magmatic-geneticrelationship between the two types of chromite. We propose thatanorthositic chromites form in an Fe-rich basaltic melt derivedfrom a komatiitic, boninitic or basaltic parent magma throughreaction between the melt and early-formed Fe-rich chromite. KEY WORDS: chromite; anorthosite; Archaean; Greenland; Re–Os 相似文献
20.
P. V. Sunder Raju 《Journal of the Geological Society of India》2013,81(5):709-712
The anorthosite complexes and related rock types of the Indian Precambrian shield are primarily associated with either cratons or mobile belts. They were metamorphosed under amphibolites to granulite facies conditions. The major rock types are chromite-bearing meta-anorthosites, amphibolites, basic granulites, pink granites and gneisses. This study was carried out on chromitite bearing samples from Sittampundi layered anorthosite complex, Tamil Nadu, to evaluate the textural and compositional relationships of rutile and chromite. The pristine composition of the chromites is still preserved inspite of intense metamorphic and tectonic process. The rutiles are differentiated into isolated, clustered and exsolved rutile grains. 相似文献