赣南地区生态环境与经济发展初步研究

赣南地区可划分为三个自然生态环境区,即：东、南部山地丘陵区、中部盆地丘陵区及西部山地丘陵区。从全区范围来说,单位耕地面积创造的农业产值与森林覆盖率呈显著正相关;而目前中部盆地丘陵区内的工业发展及西部山地丘陵区的农业发展与区内森林植被覆盖率呈负相关。     

勉略宁地区区域地质背景,矿床类型及其成矿特点

以地质演化为基础,从沉积－构造－岩浆－变质－成矿作用角度进行综合对比分析,提出煎茶岭—七里店和黑木林—峡口驿两大构造岩浆带对勉略宁地区矿床起主控作用, 认为各类型矿床成矿作用与先存基底岩石有成生关系, 将矿床形成时代统一在秦岭陆－陆碰撞时限范围, 对该地区地质找矿工作及矿床理论研究进行了讨论。     

陕北延安地区基底断裂及其油气地质意义

以重磁力资料为基础,结合钻井及地质地震资料,推测出研究区有8条基底断裂。已有油田大都沿基底断裂走向分布在断裂两侧,勘探井的试气产量高低与基底断裂分布关系密切,基底断裂的"隐性"活动导致沉积盖层中发育构造裂缝且以垂直裂缝为主,裂缝不仅能作为油气运移的通道,而且能提高储层的孔隙度和渗透率,对研究区内油气分布及储层产能起关键作用。     

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

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.     

新疆葫芦铜镍硫化物矿床的地质特征与成矿时代

哈密葫芦铜镍矿是东天山地区典型的与基性-超基性岩有关的岩浆成因块状硫化物矿床.对其中含铜镍硫化物的基性-超基性岩用Re-Os等时线法定年,获得(283±13)Ma的等时线年龄.这表明,葫芦与东天山其他铜镍矿床乃至喀拉通克和箐布拉克铜镍硫化物矿床一样,主要形成于海西期,同位素年代学界定的成岩成矿时间大致在320~280 Ma,表明海西晚期在新疆北部为一个与基性-超基性岩有关的铜镍矿床成矿高峰期.     

新疆金山金矿床中Cu-Zn合金矿物的发现及其地质意义

在研究新疆金山金矿床物质组分的过程中,通过对矿石矿物进行反光显微镜下观察与电子探针分析,发现了Cu-Zn合金矿物。与国内外已发现的Cu-Zn合金矿物相比,所发现的Cu-Zn合金矿物中Cu含量(81.35%～85.36%,平均83.75%)较高,Zn含量(6.08%～10.10%,平均为7.39%)较低,并含少量的Sn(4.13%～6.75%,平均为5.23%)、Ni(0.88%～1.38%,平均为1.05%),属于为α相Cu-Zn合金矿物。Cu-Zn合金矿物在自然界极为罕见,其生成条件也很独特。结合金山金矿成矿特征和形成条件,作者认为该Cu-Zn合金矿物是在热液成矿晚阶段(第Ⅳ阶段)强还原条件下的缺氧、缺硫环境中形成的。     

Does continental crust transform during eclogite facies metamorphism?

Eclogites within exhumed continental collision zones indicate regional burial to depths of at least 60 km, and often more than 100 km in the coesite‐stable, ultra‐high pressure (UHP) eclogite facies. Garnet, omphacitic pyroxene, high‐Si mica, kyanite ± coesite should grow at the expense of low‐P minerals in most felsic compositions, if equilibrium obtained at these conditions. The quartzofeldspathic rocks that comprise the bulk of eclogite facies terranes, however, contain mainly amphibolite facies, plagioclase‐bearing assemblages. To what extent these lower‐P minerals persisted metastably during (U)HP metamorphism, or whether they grew afterwards, reflects closely upon crustal parameters such as density, strength and seismic character. The Nordfjord area in western Norway offers a detailed view into a large crustal section that was subducted into the eclogite facies. The degree of transformation in typical pelite, paragneiss, granitic and granodioritic gneiss was assessed by modelling the equilibrium assemblage, comparing it with existing parageneses in these rocks and using U/Th–Pb zircon geochronology from laser ablation ICPMS to establish the history of mineral growth. U–Pb dates define a period of zircon recrystallization and new growth accompanying burial and metamorphism lasting from 430 to 400 Ma. Eclogite facies mafic rock (~2 vol.% of crust) is the most transformed composition and records the ambient peak conditions. Rare garnet‐bearing pelitic rocks (<10 vol.% of crust) preserve a mostly prograde mineral evolution to near‐peak conditions; REE concentrations in zircon indicate that garnet was present after 425 Ma and feldspar broke down after 410 Ma. Felsic gneiss – by far the most abundant rock type – is dominated by quartz + biotite + feldspar, but minor zoisite/epidote, phengitic white mica, garnet and rutile point to a prograde HP overprint. Relict textures indicate that much of the microstructural framework of plagioclase, K‐feldspar, and perhaps biotite, persisted through at least 25 Ma of burial, and ultimately UHP metamorphism. The signature reaction of the eclogite facies in felsic rocks – jadeite/omphacite growth from plagioclase – cannot be deduced from the presence of pyroxene or its breakdown products. We conclude that prograde dehydration in orthogneiss leads to fluid absent conditions, impeding equilibration beyond ~high‐P amphibolite facies.     

横断山不同成因类型花岗岩类岩石中黑云母的标型特征

本文研究了横断山区不同成因类型花岗岩类岩石中黑云母的化学成分、微量元素、结构和物理性质等。结合花岗岩类岩石的成因类型,将黑云母分为三个亚种:富镁黑云母(MF=1.3—1.5)、镁黑云母(MF=1—1.3)和富铁黑云母(MF=0.5-1)。     

内蒙甲生盘层控硫铅锌矿床汞的岩石地球化学特征

本文以526个岩石样品的Hg、Zn测定及闪锌矿单矿物Hg的热释温度测定为基础,探讨了甲生盘层控硫铅锌矿床Hg的岩石地球化学异常特征,提出了以Hg×100/Zn为指标研究成矿后侵入体的热力对Hg的驱赶作用的可能性。从岩体向外250m的距离内,该比值逐渐从2升高到7。原生Hg异常的研究有利于解释该地壤中汞气异常的形成。已经证实,壤中汞气测量对寻找这类矿床是有效的。     

横断山区花岗岩类中角闪石的标型特征及其成因意义

本文研究了横断山区不同成因类型花岗岩中角闪石的化学成分、微量元素、稀土元素、晶胞参数和物理性质等特征。按化学成分对角闪石作了晶体化学成因分类。在三种不同成因类型角闪石中，其M值[M=Mg/(Mg Fe^2 )]各不相同；幔型M＞0．7，壳幔型M＝0．7－0．5，壳型M<0．5。