Synthetic fluid inclusions - VI. Quantitative evaluation of the decrepitation behaviour of fluid inclusions in quartz at one atmosphere confining pressure   总被引：1，自引：0，他引：1  

R. J. BODNAR  P. R. BINNS  D. L. HALL 《Journal of Metamorphic Geology》1989,7(2):229-242

ABSTRACT The decrepitation behaviour of fluid inclusions in quartz at one atmosphere confining pressure has been evaluated using pure H₂O synthetic inclusions formed by healing fractures in natural quartz. Three different modes of non-elastic deformation, referred to as stretching, leakage or partial decrepitation, and total decrepitation have been observed. The internal pressure required to initiate non-elastic deformation is inversely related to inclusion size according to the equation: internal pressure (kbar) = 4.26 D^-0.423 where D is the inclusion diameter in microns. Regularly shaped inclusions require a higher internal pressure to initiate non-elastic deformation than do irregularly shaped inclusions of similar size. Heating inclusions through the α/β quartz inversion results in mechanical instability in the quartz crystal and leads to mass decrepitation of inclusions owing to structural mismatches generated by pressure gradients in the quartz around each inclusion. Long-term heating experiments (∼2 years) suggest that the internal pressure required to initiate non-elastic deformation does not decrease significantly with time and indicates that short-lived thermal fluctuations in natural systems should not alter the inclusion density and homogenization temperature. Inclusions that do exhibit decreased density (higher homogenization temperature) are, however, always accompanied by a change in shape from irregular to that of a negative crystal. Observations of this study are consistent with elasticity theory related to fracture generation and propagation around inclusions in minerals. These results indicate that an inclusion will not be influenced by a neighbouring inclusion, or other defect in the host phase, as long as the distance between the two is >2–4 diameters of the larger of the two inclusions.  相似文献   

Quartz microtextures of the Sambagawa schists and their implications in convergent margin processes   总被引：1，自引：0，他引：1  

Nobuo  Sakakibara  Ikuo  Hara  Kenji  Kanai  Kenji  Kaikiri  Tugio  Shiota  Kei  Hide Peter  Paulitsch 《Island Arc》1992,1(1):186-197

Abstract Quartz c-axis fabrics of the Sambagawa schists produced along a late Mesozoic convergent plate margin were analysed so that their tectono-metamorphic history could be clarified. It has been noted by many authors that quartz fabrics produced by earlier phase deformation are easily modified by strain increment during later phase deformation. This paper attempts to elucidate the high-temperature phases of prograde metamorphism (Sim-Bim phase) and of retrograde metamorphism (Sb₁ phase and Sb₂₋₁ phase) from quartz grains included in garnet and plagioclase porphyroblasts. Quartz c-axis fabrics for all these phases are explained in terms of a type I crossed girdle, without (only rarely with) higher concentration in the principal axis of strain Y (X>Y>Z), that must have been produced by the activity of a dominant slip system such as rhomb and basal. As a result, the plastic deformation of quartz, which was responsible for the formation of the type I crossed girdle, occurred even under temperatures greater than 500°C and pressures a little greater than 10–11 kb, which correspond to the physical condition of the Sim-Bim phase. It has been assumed that a high strain rate (and/or low H₂O content) caused rhomb and basal to be active as dominant slip systems in the subduction zone related to the formation of the Sambagawa schists even under high temperatures (> 500°C).  相似文献   

石湖金矿区中石英的找矿信息研究     

杨殿范  刘荣访  李高山  贾克实 《吉林大学学报(地球科学版)》1992,(3)

石英与金矿床关系十分密切,石英中含有众多的信息.通过对它的研究,可提取出许多找金矿的信息或标志.石英热发光曲线反映金的矿化强度,矿体中的石英热发光曲线呈双蜂或多峰;而矿化带中则呈包含多种隐伏峰的单蜂曲线.与成矿有关的石英红外吸光度D_2、D_2/D_1可定性地评价其含金性.含金石英中的Al_2O_3、K_2O、Na_2O、H_3O~(+)的含量随着矿体埋藏深度的增大而增加,可用其判别矿体的埋藏深度.  相似文献   

应用微晶石英标型特征研究某隐伏铀矿床的垂直分带     

倪师军  金景福 《矿物学报》1992,12(3):243-250

所研究的矿床为一个大型隐伏铀矿床,是华南铀成矿区一个典型的花岗岩型铀矿床。本文重点研究了该铀矿床主成矿阶段微晶石英的标型特征。在矿床垂直方向上,微晶石英的杂质组分、晶胞参数和人工热释光(ATL)性质均显示较大的变化。微晶石英标型特征的这些差异可以作为研究隐伏铀矿床垂直分带的有效手段,并可用于判断其侵蚀截面。  相似文献   

The Thermal History of the Huangmeijian Granite Intrusion in Anhiii and Its Relation to Mineralization: Isotopic Evidence     

Zheng Yongfei  Fu Bin  Gong Bing 《《地质学报》英文版》1996,9(2):168-180

Abstract Whole—rock Rb—Sr, zircon U—Pb and hornblende, biotite and K—feldspar K—Ar ages are used to reconstruct the cooling history of the Huangmeijian intrusion in the Anqing—Lujiang quartz—syenite belt in Anhui. Oxygen isotope geothermometry of mineral pairs demonstrates that diffusion is a dominant factor controlling the closure of isotopic systems. Assuming the cooling of the intrusion is synchronous with a dicrease in local geothermal gradients, an emplacement depth of about 8 km and the magma crystallization temperature of 800 ± 50°C are estimated. The Huangmeijian intrusion experienced a rapid cooling process and uplifted after its emplacement and crystallization at 133 Ma B.P. with a cooling rate of 34.5°C / Ma and an uplifting rate of 0.35 mm/ a. The intrusion was rising until it rested at a depth of 3 km at a temperature of 300 ± 50°C about 14 Ma later. Then the intrusion was in slow cooling and uplifting with a cooling rate of 4.4°C / Ma and an uplifting rate of 0.04 mm/ a. U—Pb dating of pitchblende is done for the hydrothermal uranium deposit formed in the contact zone of the Huangmeijian intrusion. The result shows that the mineralization age is close to the closing time of the K—Ar system in biotite. The fluid inclusion thermometry indicates that the mineralization temperature is in agreement with the closure temperature of the biotite K—Ar system. This suggests a close relationship between the slow cooling of the intrusion and the hydrothermal uranium mineralization process.  相似文献   

石英热发光在金矿找矿中的意义   总被引：1，自引：0，他引：1  

杨殿范  刘荣访 《矿物学报》1993,13(2):190-195

本文介绍了石英热发光在某些金矿床中矿体的不同部位的变化特征。利用石英热发光特征可以区分、评价不同成矿阶段的石英和石英脉的含金性。总结出含金石英脉的石英热发光曲线为双峰或多峰,而不含金的石英脉则为单峰曲线,并探索了石英热发光作为金矿找矿标志的规律及其意义。  相似文献   

电热石英管中氢化锗原子化过程的研究     

郑衍生  王明慧 《岩矿测试》1993,12(2):101-104

研究了H_2和O_2对GeH_4原子化的影响,H_2的存在引发了自由H基的产生,GeH_4在自由H基的碰撞下原子化。伴生GeO的形成导致Ge的原子吸收信号降低。  相似文献   

临川县云山区金矿化的控制条件及其判别标志     

杨吉根 《华东地质学院学报》1994,17(4):330-339

  相似文献   

辽宁丹东五龙金矿矿化类型及其构造控制机理   总被引：7，自引：1，他引：7  

吕贻峰  商维国 《现代地质》1994,8(3):309-316

位于辽宁丹东地区的五龙金矿受ＮＥ向剪切系统控制．在剪切带发展演化过程中，于不同阶段形成不同类型的金矿化。在早期韧性剪切带上升剥蚀阶段出现的ＮＥ向脆－韧性线状剪切带，控制同剪切带型金矿；叠加在韧性剪切带之上的ＮＮＥ向一级断裂控制破碎带蚀变岩型金矿的形成和分布；沿ＳＮ向和ＮＷ向的二级断裂构造控制含金石英脉型金矿。  相似文献   

河北张家口金矿石英的标型特征及其成因意义   总被引：2，自引：0，他引：2  

银剑钊  史红云 《岩石矿物学杂志》1994,13(1):78-89

本文详尽地研究了张家口金矿两种主要含矿石英（乳白色石英和烟灰色石英）的气液包裹体特征、显微变形特征、成分标型特征、气液包裹体成分特征及晶胞参数标型特征，对比了两种石英含金性的差异与上述各类特征间的关系，并将该矿床的石英标型特征与国内外一些典型矿床的石英标型特征进行了对比，在此基础上得出：烟灰色石英与乳白色石英具有不同的气液包裹体特征、显微变形特征和微量元素特征，张家口金矿的成矿溶液为一种具低中等盐度、弱碱性、Ｎａ￣（＋）－Ｃａ￣（２＋）－Ｃｌ￣（－）型及Ｎａ￣（＋）－Ｃａ￣（２＋）－ＳＯ型、中深成、中高温热水溶液。结合矿床产出的地质背景，文章最后得出：张家口金矿为中高温、中深成变质热液型金矿床。  相似文献