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Search Results: 1 - 10 of 2377 matches for " contact metamorphism "
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Review on the classification of metamorphism types and suggestion of a new tentative classification

SHEN QiHan,GENG YuanSheng,

岩石学报 , 2009,
Abstract: Based on a history review of the advancement in classification of the metamorphism types, this paper has proposed a tentative and systematic classification of types of metamorphism. Metamorphism can be divided into two great types: Local and regional metamorphism, each of which involves 4 or 5 types. Local metamorphism is divided into the following five types: (1) contact metamorphism which includes three subtypes, i.e.thermal metamorphism, contact metasomatic metamorphism and pyro-metamorphism; (2) low-medium-high temperature dynamic metamorphism involving two subtypes such as low-medium-high temperature ductile shear zone metamorphism and temperature- and pressure-increasing thrust metamorphism; (3) impact (or shock) metamorphism; (4) hydrothermal metamorphism; (5) burn metamorphism. Regional metamorphism is divided into the following four types; (6) Early Precambrian craton metamorphism or low-medium pressure to medium-high temperature regional metamorphism which include five subtypes: low-medium pressure amphibolite facies metamorphism, low-medium pressure granulite facies metamorphism, low-medium pressure amphibolite facies-granulite facies metamorphism, low-medium pressure greenschist to amphibolite facies progressive metamorphism and regional ultrahigh temperature granulite facies metamorphism; (7) orogenic metamorphism including three subtypes: i.e.low-temperature-low-pressure regional dynamic metamorphism, collision metamorphism and deep subduction zone high-ultrahigh pressure metamorphism; (8) burial metamorphism; and (9) ocean-floor metamorphism.
Ultramafic Hornfelses in Central Iran Ophiolites
Ghodrat Torabi
Journal of Applied Sciences , 2008,
Abstract: There are leucocratic gabbro intrusions in serpentinized mantle peridotites of Central Iran ophiolites (Jandaq, Anarak, Naein and Ashin-Zavar). In contacts of gabbro intrusions and serpentinized mantle peridotites, ultramafic hornfelses are formed by contact metamorphism. These ultramafic hornfelses are different with host mantle peridotite in petrography, texture and mineral chemistry. Two-pyroxene thermometry of hornfelses and intact mantle peridotites that are far from contact metamorphism, present 987 and 1200°C, respectively. To occuring the reaction between the gabbro intrusions and mantle peridotites, the host rock should be serpentinized previously.
Contact metamorphism of Silurian black shales by a basalt sill: geological evidence and thermal modeling in the Barrandian Basin
Suchy V,?afanda J,Sykorová I,Stejskal M
Bulletin of Geosciences , 2004, DOI: 10.3140/bull.geosci.2004.03.133
Abstract: Organic-rich shales of the Liteň Formation (Silurian) were intruded by a series of several-meter thick doleritic basalt sills soon after their deposition. The effect of rapid thermal stress on organic and mineral diagenesis of shales around a representative 4mthick sill has been studied using optical microscopy, Fourier-Transform infrared (FT-IR) and micro-Raman spectroscopy of dispersed graptolite particles, gas chromatography-mass spectrometry (GC-MS) of organic extracts, and X-ray diffraction (XRD) of the clay fraction. Our data suggest that the sills have only had a local effect on the thermal maturity of the adjacent sediments. Graptolite reflectance values (3.0-3.6% Rmax) and bireflectance (up to 3.1%) higher than the regional diagenetic background (~1.8 Rmax) were found to be restricted to the narrow zone immediately adjacent to the igneous contacts, with detectable alteration starting to take effect at about 70 to 80% of sill thickness. Based on recent empirical correlations, these values may indicate contact-metamorphic temperatures between 320-420 °C. The optical properties of graptolite fragments within the contact aureole correlate closely with the chemical and structural transformation as expressed by FT-IR and Raman spectroscopy data. The graptolite periderm undergoes systematic depletion of aliphatic-containing groups toward the igneous contacts, and transforms into a condensed aromatic residuum of an increased crystalline ordering, similar to high-rank coal or kerogen. Extractable organic matter within the immediate contact zone is strongly depleted, but appreciably higher concentrations were obtained at a distance of 1.2mbelow the intrusion. This suggests that the organic matter along the contact was gasified during the igneous event, and the expelled volatiles condensed in 'micro-reservoirs' a certain distance from the sill. In contrast to the organic matter, clay minerals from the contact aureole reveal a lower degree of thermal metamorphism. The values of illite crystallinity (IC; up to 0.44° Δ2θ) and chlorite crystallinity (ChC; 0.30-0.34° Δ2θ) recorded in a narrow contact zone imply only minor elevation above the regional diagenetic background (IC ~ 0.60-0.70° Δ θ), and broadly evidence paleotemperatures in the range of 170-300 °C. The apparent discrepancy between the degree of thermal transformation of the organic matter and the clay minerals can be ascribed to the greater sensitivity of organic materials to geologically short metamorphic heating. The results from computer thermal modeling of the sill do not match the empirical ge
The hornblende-plagioclase hornfels from the contact aureole of the Tanvald granite, northern Bohemia - the raw material for Neolithic tools
Klomínsky J,Fediuk F,Schovánek P,Gaba?ová A
Bulletin of Geosciences , 2004, DOI: 10.3140/bull.geosci.2004.01.063
Abstract: A hornblende-plagioclase hornfels is described from a new exposure near the village of Je manice, where it is present as a 30-35 cm thick layer within spotted phyllites at the exocontact of the Krkono e-Jizera granite massif in northern Bohemia. The hornfels layer seems to be part of the Poniklá Group of Ordovician -Upper Silurian age. It corresponds to the metabasites used in the production of Neolithic artifacts (e.g., the Jistebsko archeological site near Jablobec nad Nisou), which were hitherto known only as loose fragments from localities on the lower slopes to the south of the granite ridge between Liberec and Tanvald. New data show that this rock is situated inside the contact aureole of the Tanvald alkali-feldspar granite, its remarkable mechanical strength being due to the effects of contact metamorphism. The hornfels corresponds compositionally to tholeiitic basalt. Its major minerals are amphiboles ranging in composition from the predominate magnesiohornblende to subordinate actinolite, calcic plagioclase, and ilmenite. This rock represents neither a dike nor a lava sheet, but rather a sill or a tuff layer modified by regional and thermal metamorphic reconstruction and tectonic deformation.

LI Zhen-sheng~,

天然气地球科学 , 2004,
Abstract: 为了定量分析碳酸盐岩接触变质作用形成的CO2,研究了松辽盆地东北缘碳酸盐岩接触变质带常量元素和稀土元素的元素分配关系。认为碳酸盐岩接触变质过程中主要体现为硅的富集和钙、碳的亏损,并且CaO、SiO2与ΣREE呈线性关系;随着变质程度增高,元素的含量、稀土元素的分布型式和分馏程度越趋向花岗岩,其主要原因是碳酸盐岩与侵入流体的混染作用、碳酸盐岩硅化及矿化过程引起的稀土变化、碳酸盐岩重结晶对轻稀土元素的富集。计算得出了CO2释放量与岩石体积比(2.7~256.7)。证明了碳酸盐岩接触变质作用是无机成因CO2形成的机制。
An Oxygen Isotope Study of Contact Metamorphic Rocks from Songshugou in North Qinling

Sun Weidong,Zheng Yongfei,Li Shuguang,Sun Yong,Zhang Guowei,

岩石学报 , 1997,
Abstract: 对北秦岭松树沟阿尔卑斯型超镁铁岩体接触变质带的角闪岩和斜长角闪片岩进行了全岩和单矿物氧同位素组成测定。矿物对氧同位素地质测温结果得到,角闪岩为745℃~770℃,角闪片岩为500℃~605℃,均与已知的岩石学温度计结果相吻合,指示了这些变质岩内部的氧同位素平衡。靠近超镁铁岩体的角闪岩受热触变质作用影响,导致了矿物之间的氧同位素再平衡;远离超镁铁岩的角闪片岩基本未受热触变质作用影响,因此氧同位素温度代表了秦岭群区域变质岩的形成温度。角闪岩和斜长角闪片岩全岩δ18O值为8.5~10.3,指示变质前原岩成分可能具有中基性火成岩特征
Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients?  [PDF]
Frank Spors, Donald J. Egan, Lance E. McNaughton, Jie Shen, Matthew J. Lampa
Open Journal of Ophthalmology (OJOph) , 2013, DOI: 10.4236/ojoph.2013.33014

Purpose: Reasons for the lack of success for contact lens patients range from poor fit, to discomfort or to a less than optimum wearing schedule. This project was a preliminary investigation of customized soft toric contact lenses as an alternative for unsuccessful contact lens patients or potential drop-outs. Methods: Fifteen healthy non-compromised, previously unsuccessful contact lens wearing patients (13 women, 2 men) with ages from 21 to 33 years (25.1 ± 2.7 years) were the subjects for this study. They were empirically fitted with 15 astigmatic and 5 spherical customized SpecialEyes soft contact lenses. Visual acuities, comfort, lens movement, and rotation were evaluated. Results: Patients fitted with customized SpecialEyes soft contact lenses had statistically significant better visual acuities than with Phoropter Manifest Refraction. The lenses used in this study centered well and moved no more than 1 mm upon each blink. Lens rotation was less than 10 degrees for all toric lenses. Patients gave very positive vision and comfort ratings. Conclusion: This preliminary study supports the application of a software program

Using Contact Metamorphic Criteria in Contact Aureole to Preliminarily Discriminate

陈能松,陈冰寒,Roger Mason,杨婷婷,夏彬,刘嵘,王国庆,徐冉
Chen Nengsong
, Chen Binghan, Roger Mason, Yang Tingting, Xia Bin, Liu Rong, Wang Guoqing, Xu Ran

地球科学(中国地质大学学报) , 2018, DOI: 10.3799/dqkx.2018.006
Abstract: 近同心状房山岩体接触变质晕中变斑晶-基质关系与变质作用P-T轨迹样式的结合可以区分岩浆底劈式侵位与气球膨胀式侵位机制.例如,该房山岩体南侧接触变质晕中的下马岭组泥质变质岩的变斑晶-基质关系显示强烈的面状压扁应变变形,其变质作用P-T轨迹具等压加热趋势,综合前人成果估算该岩体4个依次侵位的岩石单元的最终就位岩浆结晶深度彼此近于一致,倾向于认为该岩体的岩浆侵位机制为气球膨胀式.
Relationship between metamorphic porphyroblasts and their matrices in the contact aureole of the concentric zoned Fangshan pluton, Beijing, combined with P-T patterns can be used as criteria to distinguish between magmatic diapirism and balloon expansion mechanisms for pluton emplacement in this study. It is found that, pelitic metamorphic rocks in the Xiamaling Formation in the southern part of the aureole display porphyroblast matrix relationships reflecting intense plane strain deformation combined with a nearly isobaric heating P-T trajectory towards the contact. Incorporating previously published estimates of final crystallization depths of four successively emplaced magmatic units, the results favor the balloon inflation intrusion mechanism
The Dabie-Sulu UHP rocks belt: review and prospect
Bolin Cong,Qingchen Wang
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02886130
Abstract: The future studies will focus on the following three subjects: ( i ) thermal dynamics of the UHP metamorphism, ( ii ) relationship between UHP metamorphism and collision orogeny, as well as their geodynamics, and ( iii ) interactions between crust and mantle, and between continental lithosphere and asthenosphere during the collision orogenic process, as well as their constraints to the evolution of continental lithosphere.
The Extremely Efficient New Model in Milling of Complicated Surfaces in 5-Axis Machining for 3-Dimensional Contact  [PDF]
Yi Lou, Huran Liu, Bo Tan
World Journal of Engineering and Technology (WJET) , 2018, DOI: 10.4236/wjet.2018.63038
Abstract: Although most of the 5-axis NC milling machine tool producers declare that their machine poses the function of 5-axis simultaneous machining, and most of the commercialized CAD/CAM software was reported it can support the 5-axis simultaneous machining, but there are very few analyses about their machining efficiency. I hope that the reader would be interested to know how the new method is?highly effective. The paper did a good job in motivating the problem mentioned here. The model of this paper is extremely efficient ant. This is a highly effective way of surface machining. There are also some areas that need improving. The mathematic presentation is not clear, but much more pages are needed, if the authors like to make it clearer. In the resent paper “The Extreme Efficiency of the New Model in Milling of Complicated Surfaces” we discussed the extreme efficiency of the new model in milling of complicated surfaces in 5-axis machining for 2-dimensional contact. While this time lets discuss the same problem but much complicated one, 5-axis machining for 3-dimensional contact. As the research activities conducted by Dr. Liu Huran opened a new field and wide horizons in 5-axis machining of sculptured complicated surfaces using mathematical theories, and according to the interesting results presented in paper, Dr. Liu Huran is strongly encouraged if he can submit a similar work but this time with a new title that corresponds to the purpose
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