鲁北新生代隐伏火山岩及其石油地质意义   总被引：1，自引：0，他引：1  

杜韫华  代贤忠 《岩石学报》1990,6(3):43-52,T001

鲁北新生代隐伏火山岩可划分为3个喷发期6个亚期,9种火山岩岩石类型和同期侵入的辉绿岩。它们形成在近大陆边缘的板内裂谷型盆地,对于富有机质生油岩的沉积、各种储集体的形成、多种含油圈闭类型的形成以及有机质成熟向烃类转化都是非常有利的。作为储集岩主要有玄武安山岩、辉绿岩和湖底玄武质凝灰岩。储油空间主要为次生孔隙和裂缝。火山岩及其有关岩石在本区不仅形成了特殊的油气藏,而且还可作为盖层、封堵层、披复构造的基岩,因此对石油地质勘探有重要意义。  相似文献   

On the significance of CO2 inclusions in plagioclase microphenocrysts in tholeiite from Moeraki,New Zealand   总被引：1，自引：0，他引：1  

Douglas S. Coombs  Edwin Roedder 《Bulletin of Volcanology》1994,56(1):23-28

Liquid plus vapour inclusions of CO₂ are widespread in plagioclase microphenocrysts in small tholeiitic intrusions and tephra of the Moeraki and adjacent areas of northeast Otago, New Zealand. They imply the presence of immiscible CO₂ droplets in the magma at depths of about 7–14 km. Their presence within 5 μm of the edges of microphenocrysts as little as 35 μm thick and 118 μm long indicates minimal feldspar crystal growth during the final ascent and quenching of the magma. Delicate branching clusters of lath-like microphenocrysts escaped disruption during this ascent. Such CO₂ inclusions are a potential source of ‘excess argon’ perturbing K-Ar age determinations. Received March 24, 1993/Accepted September 10, 1993  相似文献   

Cryptic crustal contamination of MORB primitive melts recorded in olivine-hosted glass and mineral inclusions     

Vadim S. Kamenetsky  Andrey A. Gurenko 《Contributions to Mineralogy and Petrology》2007,153(4):465-481

The origin of compositional heterogeneities among the magmas parental to mid-ocean ridge basalts (MORB) was investigated using a single rock piece of the olivine-phyric basalt from 43°N, Mid-Atlantic Ridge (AII D11-177). The exceptional feature of this sample is presence of very primitive olivine crystals (90–91 mol% Fo) that are significantly variable in terms of CaO (0.15–0.35 wt%). A population of low-Ca olivine (0.15–0.25 wt% CaO) is also notably distinct from high-Ca olivine population in AII D11-177, and primitive MORB olivine in general, in having unusual assemblage of trapped mineral and glass inclusions. Mineral inclusions are represented by high-magnesian (Mg# 90.7–91.1 mol%) orthopyroxene and Cr-spinel, distinctly enriched in TiO₂ (up to 5 wt%, c.f. <1 wt% in common MORB spinel). Glass inclusions associated with orthopyroxene and high-Ti Cr-spinel have andesitic compositions (53–58 wt% SiO₂). Compared to the pillow-rim glass and “normal” MORB inclusions, the Si-rich glass inclusions in low-Ca olivine have strongly reduced Ca and elevated concentrations of Ti, Na, K, P, Cl, and highly incompatible trace elements. Strong variability is recorded among glass inclusions within a single olivine phenocrysts. We argue that the observed compositional anomalies are mineralogically controlled, and thus may arise from the interaction between hot MORB magmas and crystal cumulates in the oceanic crust or magma chamber.  相似文献   

高温高压下橄榄石含水实验和软流圈成因   总被引：1，自引：0，他引：1  

顾芷娟  孙天泽  陶京岭 《地球物理学进展》2001,16(3):40-46

高温高压橄榄石含水实验表明，水进入橄榄石能加速其塑性形变，促进了地幔塑性流动，为上部软流圈成因提供一种新的可能依据。  相似文献   

High-temperature creep in a Ni2GeO4: a contribution to creep systematics in spinel     

J. D. Lawlis  Y.-H. Zhao  S. Karato 《Physics and Chemistry of Minerals》2001,28(8):557-571

 High-temperature creep behavior in Ni₂GeO₄ spinel was investigated using synthetic polycrystalline aggregates with average grain sizes ranging from submicron to 7.4 microns. Cylindrical samples were deformed at constant load in a gas-medium apparatus at temperatures ranging from 1223 to 1523 K and stresses ranging from 40 to 320 MPa. Two deformation mechanisms were identified, characterized by the following flow laws: where σ is in MPa, d is in μm and T is in Kelvin. These flow laws suggest that deformation was accommodated by dislocation creep and grain-boundary diffusion (Coble) creep, respectively. A comparison with other spinels shows that an isomechanical group can be defined for spinels although some differences between normal and inverse spinels can be identified. When creep data for olivine and spinel are normalized and extrapolated to Earth-like conditions, spinel (ringwoodite) has a strength similar to olivine in the dislocation creep regime and is considerably stronger than olivine in the diffusion creep regime at coarse grain size. However, when grain-size reduction occurs, spinel can become weaker than olivine due to its high grain-size sensitivity (Coble creep behavior). Analysis of normalized diffusion creep data for olivine and spinel indicate that spinel is weaker than olivine at grain sizes less than 2 μm. Received: 18 June 2000 / Accepted: 3 April 2001  相似文献   

人工多晶橄榄石样品孔隙压缩高温高压实验研究   总被引：1，自引：1，他引：0  

孙天泽 《地球物理学进展》2000,15(4):27-34

人工制备多晶橄榄石样品的高孔隙度是实验关注的问题之一。本文着重研究在给定温度条件下人工多晶橄榄石样品高温高压孔隙压缩问题。文中给出了含水的湿样品和干燥样品孔隙度与实验压力的关系曲线,并提出了衡量样品压实程度的压实系数Ｖｏ／Ｖ的概念。  相似文献   

橄榄石的晶格优选定向、含水量与地震波各向异性:对大陆俯冲带变形环境的约束   总被引：4，自引：0，他引：4  

王勤嵇少丞  许志琴 《岩石学报》2007,23(12):3065-3077

橄榄石在不同热动力学条件下形成的晶格优选定向是认识上地幔塑性变形与地震波各向异性的基础。本文通过总结橄榄石的晶格优选定向、含水量与地震波各向异性的研究进展,探讨大陆俯冲带的变形环境。绝大部分天然变形橄榄岩中的橄榄石都发育了[100](010)组构:[100]轴近平行于线理,(010)面平行或近平行于面理,使橄榄岩的最快P波速度近平行于线理,最大S波分裂平行面理并垂直线理。但来自超高压变质带的石榴石橄榄岩可发育[001](100)组构,使橄榄岩的最快P波速度和最小S波分裂方向垂直面理。近年来的变形实验与理论计算表明:超高压和低温是橄榄石组构从[100](010)向[001](100)转变的关键因素,而水对橄榄石流变行为的影响还有待进一步研究。对170个天然橄榄石结构水含量的统计结果表明:橄榄石含水量变化很大(0～170×10~(-6)H_2O),玄武岩中橄榄岩包体的橄榄石比较贫水,而所有富水橄榄石均来自克拉通金伯利岩中的石榴石橄榄岩。因此,除了水在上地幔的不均匀分布,橄榄岩折返过程中氢的扩散会强烈影响橄榄石的含水量。苏鲁芝麻房橄榄岩提供了以超高压、低温、贫流体为特征的大陆俯冲带中[001](100)橄榄石组构的实例。在俯冲的大陆板片中,橄榄石组构在120～220 km从[100](010)向[001](100)的转变可导致地震波各向异性突然降低,而且最快P波速度垂直于俯冲方向。  相似文献   

The Role of Pressure in Producing Compositional Diversity in Intraplate Basaltic Magmas   总被引：3，自引：0，他引：3  

Whitaker  M. L.; Nekvasil  H.; Lindsley  D. H.; Difrancesco  N. J. 《Journal of Petrology》2007,48(2):365-393

Basaltic magmas found in intraplate suites appear to followmore than one differentiation trend. Many ocean island suitesfollow the ocean island tholeiitic trend, with the basalts differentiatingfrom olivine tholeiite through basaltic andesite, andesite,and dacite to sodic rhyolite. Many continental intraplate magmaticregimes, such as those of the Snake River Plain and the plutonicsequences associated with massif anorthosites, follow the potassicsilica-saturated alkalic trend, in which basalt differentiatesfrom olivine tholeiite through ferrobasalt (jotunite or ferrodiorite),Fe-rich intermediate rocks (trachybasalt or monzonite), andtrachyte (syenite) to potassic rhyolites and granites. Crystallizationexperiments on an olivine tholeiite from the Snake River Plainshow that the basaltic portions of the ocean island tholeiitictrend and the potassic silica-saturated alkalic trend (whichleads to strong alkali, P, Ti, and Fe enrichment and silicadepletion) can arise from the same ‘dry’ tholeiiticparental magma. These compositional differences are inducedby changes in phase equilibria as a function of pressure, withthe ocean island tholeiitic series arising from crystal–liquiddifferentiation at low pressure and the potassic silica-saturatedalkalic series arising via differentiation at elevated pressures. KEY WORDS: tholeiite differentiation; experimental petrology; phase equilibria; ferrodiorite; ferrobasalt  相似文献   

俯冲带温度条件下橄榄石中硅氧四面体的非谐振动:透射红外光谱研究     

王霏  刘曦  郑海飞  张立飞 《岩石学报》2015,31(7):1891-1900

橄榄石既是上地幔的主要矿物,又是俯冲板块的主要矿物。在正常地幔温度条件下,橄榄石中原子之间的振动是非谐振动,这已成为学界共识;然而,对于俯冲带的较低温情况,橄榄石中原子之间的振动的非谐性是否重要,目前还没有比较一致的结论。本研究利用透射红外光谱的方法,系统研究了室温下不同厚度橄榄石中硅氧四面体的红外光谱特征,并着重对其在2100~1500cm-1区域形成的二倍频峰/合频峰进行了指认。在此基础上,本研究通过采集不同温度下的透射红外光谱数据(最高温度达约450℃),确立了橄榄石中硅氧四面体的相应基频峰及二倍频峰峰位对温度的依赖性,进而得出其相应红外振动的非谐系数(χ)随温度(T)的变化关系,具体为:χ838=6.37(2)×10-7×T+0.0014(1)及χ993=7.86(3)×10-7×T+0.0015(1),其中温度的单位为℃。外推到600℃时,有χ838=0.0018(1)及χ993=0.0020(2)。这些结果表明,在俯冲带的较低温条件下,橄榄石中硅氧四面体的内部振动的非谐性可能不重要。  相似文献   

Large-strain deformation and strain partitioning in polyphase rocks: Dislocation creep of olivine–magnesiowüstite aggregates     

Misha Bystricky  Florian Heidelbach  Steve Mackwell   《Tectonophysics》2006,427(1-4):115

Aggregates composed of olivine and magnesiowüstite have been deformed to large strains at high pressure and temperature to investigate stress and strain partitioning, phase segregation and possible localization of deformation in a polyphase material. Samples with 20 vol.% of natural olivine and 80 vol.% of (Mg_0.7Fe_0.3)O were synthesized and deformed in a gas-medium torsion apparatus at temperatures of 1127 °C and 1250 °C, a confining pressure of 300 MPa and constant angular displacement rates equivalent to constant shear strain rates of 1–3.3 × 10^− 4 s^− 1. The samples deformed homogeneously to total shear strains of up to γ  15. During constant strain rate measurements the flow stress remained approximately stable at 1250 °C while it progressively decreased after the initial yield stress at the lower temperature. Mechanical data, microstructures and textures indicate that both phases were deforming in the dislocation creep regime. The weaker component, magnesiowüstite, controlled the rheological behavior of the bulk material and accommodated most of the strain. Deformation and dynamic recrystallization lead to grain refinement and to textures that were not previously observed in pure magnesiowüstite and may have developed due to the presence of the second phase. At 1127 °C, olivine grains behaved as semi-rigid inclusions rotating in a viscous matrix. At 1250 °C, some olivine grains remained largely undeformed while deformation and recrystallization of other grains oriented for a-slip on (010) resulted in a weak foliation and a texture typical for pure dry olivine aggregates. Both a-slip and c-slip on (010) were activated in olivine even though the nominal stresses were up to 2 orders of magnitude lower than those needed to activate these slip systems in pure olivine at the same conditions.  相似文献