Metamorphic processes: a celebration of the career contribution of Ron Vernon     

Michael Brown  Geoffrey L. Clarke 《Journal of Metamorphic Geology》2002,20(1):1-7

This Special Issue is in celebration of the career contribution of Ron Vernon. It arises from the ‘Ron Vernon Symposium’, which was held as part of the 15th Australian Geological Convention in Sydney in 2000. To date Ron has published more than one hundred scientific papers, several books and contributed widely to international conferences. He is the doyen in the multidisciplinary field of microstructures, which spans petrology and structural geology. However, Ron's range is phenomenal, and he has contributed to many aspects of metamorphism, magmatism and rock deformation. He has drawn on data from his work in these areas to contribute widely to understanding thermal regimes, crustal evolution and tectonics, as exemplified by his ideas about HTLP metamorphism and emplacement of granites. Ron has followed the scientific method in his work; it has led him to many innovative interpretations, some of which undermined established dogma. By example, Ron has been a positive role model for the younger generation. However, for the older generation, he has been something of a bête noire! The papers in this Special Issue cover the range from low‐ to high‐grade metamorphism, from metasomatism to melting, from microstructures to tectonics, and from fieldwork to experiments. It is our hope that in reading them you will take time to think about what has been achieved in the past 40 years, and use this as motivation for what remains to be done.  相似文献   

微粒对多晶冰流变行为的影响(Ⅱ):显微组织演变     

宋旼 《冰川冻土》2009,31(1):101-105

通过光学显微镜及单轴压缩的方法,研究了不同应力和温度下微粒对多品冰流变过程中显微组织演变的影响.研究表明:不论高温还是低温,或者高应力还是低应力,含微粒的多晶冰总是有较高的流变速率.在-10℃及1.45 MPa的应力下,两种冰在流变过程中的动态再结晶通过新生晶粒沿晶界的形核及长大完成.由于微粒在流变过程中通过阻碍晶界滑移而发展高的内应力,含微粒的多晶冰有较高的动态再结晶速率,其晶粒尺寸远小于不含微粒的多晶冰的晶粒尺寸.在-5℃、-10℃及0.4 MPa的应力下,由于微粒在流变过程中同样通过阻碍晶界滑移而发展较高的内应力,含微粒的多晶冰在流变过程中的动态再结晶仍然通过新生晶粒沿晶界的形核及长大完成.而对于不含微粒的多晶冰,由于流变应力较低,晶界应变能不足以诱发新生晶粒的形核,因此动态再结晶通过应变诱发的晶界迁移完成,其结果是晶粒的尺寸保持不变.  相似文献   

上部地壳岩石流动与显微构造演化--天然与实验岩石变形证据     

刘俊来 《地学前缘》2004,11(4):503-509

岩石流动性和变形显微构造的发育直接受温度、压力、应变速率和流体相等制约 ,致使在不同地壳层次岩石的流动性表现出很大的差异。对上部地壳环境条件下天然和实验变形岩石的显微构造分析揭示出一系列具有不同特点以及由不同的成核、扩展和联合方式形成的破裂与微破裂型式的存在。讨论了在上部地壳环境中 ,温度与围压的变化对岩石破裂的影响 ,并阐述了高压破裂与低压破裂及其力学、流变学和显微构造特点 ,提出高压破裂对应于天然变形环境下出现的剪切 (挤压 )破裂 ,而碎裂岩带是典型的天然低压破裂 ,其低压环境的出现可以是浅部低围压或深部高流体压力所致。流体相的存在不仅可以引起石英 ,也可以引起方解石类碳酸盐岩矿物的水解弱化 ,并进而导致岩石流动机制的转变。岩石变形及流体等因素所致的岩石粒度变化 ,则从另一个方面影响着上部地壳岩石流动性的变化。从变形环境考虑 ,随着深度的加大 ,温度和压力升高 ,导致岩石由脆性向韧性转变 ;转变域内岩石的变形是一个复杂过程 ,是多种不同脆性和晶质塑性机制的综合。  相似文献   

珊瑚羟基磷灰石人工骨物理化学性质研究   总被引：4，自引：0，他引：4  

李兆麟  李文  薄遵昭  尹庆水  张余  于波  邸文 《矿物岩石地球化学通报》2007,26(1):52-56

将天然矿物材料珊瑚经自行设计的创新工艺流程“热液交换反应”合成出珊瑚羟基磷灰石(CHA)。利用扫描电镜、电镜图像处理、扫描电镜能谱、化学分析、ICP-AES和X射线衍射等方法测定其物理化学性质,并应用于临床。自行研制的CHA人工骨色白,孔隙率为25.87%~53.58%,与人骨及原珊瑚的孔隙率近似,莫氏硬度为3~4,抗压强度4.87~12.31MPa。化学成分:CaO=53.13%~64.09%,P2O5=35.52%~46.48%),CaO/P2O5=1.143~1.804。ICP-AES分析共测定24种微量元素,除Ca、P、K、Na、Al及Sr含量较高外,Pb、Co、Ni、Ba、Mn、Cr、Th、V、Cu、Ti、Mo、Zn、Mg、Nb、Be、Sc、Na和Li等,其质量分数均在(n~10n)×10-6范围,为人体所能承受含量。测试结果表明,人工骨色泽、孔隙结构和化学成分与人骨相近,具良好的生物相容性和骨传导性。临床应用60余例,无毒,无副作用,成骨能力强,是一种良好的骨移植替代品。  相似文献   

云南墨江含金脆—韧剪切构造带中显微构造的矿物地球化学研究   总被引：3，自引：2，他引：3  

方维萱  胡瑞忠  王明再  刘世荣  谢桂青 《矿物学报》2001,21(4):602-608

墨江－元江镍金矿床是哀牢山构造－成矿带上一个十分典型和重要的矿床，在野外实测构造岩石地层层序、矿物学详细填图的基础上，采用X射线粉晶衍射分析、扫描电镜、电子探针微区分析及矿物－构造－地球化学等方法，对墨江镍金矿床中含金脆－韧性剪切构造带的物质组成进行详细研究。显微构造的矿物地球化学研究是一种构造筛分新方法。脆性构造主要表现为含镍金石英脉－硅质岩－黄铁矿硅质岩中普遍发育碎裂岩化及裂隙，碎裂岩化－裂隙构造是深源热流体叠加成矿的储矿构造和运移上升通道，脆性剪切变形过程中伴有粘土化蚀变，粘土矿物主要有铬水云母、铬高岭石、多水铬高岭石、绿铬高岭石、铬蒙脱石、铬迪开石、铬埃洛石和绿鳞石等。在含金脆－韧剪切构造带中，铬绢云母－铬水云母－铬伊利石系列和铬绿泥石的矿物具（脆）韧剪切变形特征，在韧剪切变形过程中伴有强烈的热流体以及H2O为主要组分的矿化剂作用。  相似文献   

孤岛油田中二中区开发中后期微型构造研究   总被引：5，自引：0，他引：5  

国景星  戴启德  王纪祥 《新疆地质》2002,20(3):267-270

从油田开发实际出发，系统总结了影响微型构造精度的主要因素、微型构造研究的方法及合理工作程序。以河流动力学理论等为依据，以孤岛油田中二中区380口井的测井测井资料及取心资料为基础，总结了研究区馆陶组上段3-5砂层组各小层的微型构造类型及特征，认为微型构造主要与河道侵蚀下切、古地形、差异压实作用等非构造作用因素有关。探讨了微型构造对油井生产及剩余油分布的影响或控制作用。  相似文献   

Nanoscale haematite–ilmenite lamellae in massive ilmenite rock: an example of 'lamellar magnetism' with implications for planetary magnetic anomalies     

S. A. McEnroe  R. J. Harrison  Peter Robinson  Falko Langenhorst 《Geophysical Journal International》2002,151(3):890-912

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Assessing the extent of disequilibrium and overstepping of prograde metamorphic reactions in metapelites from the Bushveld Complex aureole, South Africa   总被引：5，自引：0，他引：5  

D. J. Waters  D. P. Lovegrove 《Journal of Metamorphic Geology》2002,20(1):135-149

Andalusite–staurolite–biotite hornfels metamorphosed beneath the mafic layered rocks of the Bushveld Complex, South Africa, preserves a detailed record of the relative timing of porphyroblast growth and metamorphic reactions. The sequence inferred from microstructures shows considerable overlap of the period of growth of porphyroblasts of staurolite, cordierite, biotite and andalusite, and the persistence over a similar interval of the reactant porphyroblastic phase chloritoid. This is inconsistent with calculations of equilibrium phase relations, and implies that disequilibrium processes controlled the prograde reaction sequence, despite the slow heating rates involved (1 °C per 10 000 yr). The early appearance of cordierite by a metastable reaction and its subsequent disappearance indicates that delayed nucleation of porphyroblastic phases, rather than simply sluggish reaction, is required to account for the sequence of growth. The predicted reactions for the first appearance of andalusite and staurolite have low entropy of reaction, and do not occur until they have been overtaken in terms of reaction affinity by high‐entropy devolatilisation reactions involving the breakdown of chlorite. Once the porphyroblasts have nucleated, metastable chloritoid‐breakdown reactions also contribute to their growth. The implied magnitude of the critical overstepping for andalusite nucleation is around 5 kJ mole^?1 (equivalent to 40 °C for the chlorite‐breakdown reaction), and that for other phases is expected to decrease in the order andalusite>staurolite>cordierite. Coupling between nucleation rate, crystal growth rates and the resulting grain size distribution suggests that the rate constants of natural reactions are at least an order of magnitude lower than those measured in the laboratory. Pseudomorphs after chloritoid and cordierite conserve volume but not Al or other species of low mobility, suggesting a breakdown mechanism controlled by an interface process such as the slow dissolution of the refractory porphyroblast phase, rather than by a transport step.  相似文献   

Incipient metamorphism and deformation in the Variscides of SW Dyfed, Wales: first steps towards isotopic equilibrium   总被引：3，自引：0，他引：3  

D. J. SLATER  B. W. D. YARDLEY  B. SPIRO  R. J. KNIPE 《Journal of Metamorphic Geology》1994,12(3):237-248

Incipient metamorphism accompanying thrusting, folding and cleavage development has been investigated in a varied sequence of Palaeozoic sediments near the Variscan front in SW Dyfed, Wales. The aim was to evaluate a critical stage in the progression from heterogeneous sediment, whose detrital phases are neither in equilibrium with one another, nor with pore fluids, through indurated sedimentary rock to metamorphic rock comprising newly formed crystals that equilibrated with one another as they grew. Quartz veins are widely developed in the area, especially in the more psammitic lithologies, while finer grained rocks became cleaved during tectonic deformation. Mineralogical constraints and fluid inclusion measurements suggest maximum temperatures around 200-310d? C (slightly higher in the Marloes-Musselwick Thrust Sheet than in other parts of the structural succession) at depths of the order of 6-13 km. Quartz veins yield distinctly heavier oxygen isotopic compositions than detrital quartz grains in the adjacent wall rocks, although care must be taken in interpreting the data because slivers of detrital grains may become incorporated into veins, while matrix detrital grains may incorporate veinlets or rims of newly formed quartz. It is concluded that vein quartz grew in isotopic equilibrium with a fluid phase whose isotopic composition was primarily controlled by exchange with phyllosilicates, not detrital quartz grains. Vein and matrix quartzes from the Marloes-Musselwick Thrust Sheet are distinctly lighter (δ¹⁸O_veins=+14 to +18% and δ¹⁸O_matrix=+11 to +14%) than those from other thrust sheets (δ¹⁸O =+17 to +20% and +14 to +17%, respectively). We conclude that vein quartz and phyllosilicate grains in cleavage domains probably attained equilibrium with a locally buffered pore fluid at the peak of metamorphism, but many relict grains of different chemical and isotopic composition remained elsewhere in the rock. Local fluid migration along veins and through cleavage lamellae facilitated the attainment of equilibrium, but there is little evidence for large-scale infiltration of externally derived fluids. With further metamorphism the quartz in these rocks would attain an isotopic composition intermediate between that of the heavy vein material and light detritus which coexist here.  相似文献   

太白山末次冰期冰碛物微结构和微构造研究     

唐永仪 《冰川冻土》1990,12(3):235-241

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