埋藏条件下蒙脱石层间水的稳定性

蒙脱石族矿物广泛存在于地表各种环境中,其层间结构的稳定性对各种表生地质作用的发生和过程起着重要作用。在砂岩成岩作用中,蒙脱石族矿物的脱水作用改变了砂岩孔隙流体的量和成分,同时也降低了油气储蓄层的孔隙度和渗透性。泥、页岩中由于蒙脱石族矿物的脱水作用,在...     

高温高压下电导-温度曲线方法进行蛇纹石的脱水温度测量及其意义

在1．0～5．0GPa压力范围内，运用高温同时高压下电导测量方法确定了蛇纹石的脱水温度。实验结果表明，压力小于2.0GPa时叶蛇纹石的脱水温度随压力的增大呈微弱升高趋势，压力大于2．0GPa时其脱水温度随压力的增大明显降低，意味着较高压力下有利于脱水反应的发生，是俯冲带岩浆作用及地幔交代作用流体的重要来源。蛇纹石脱水后，由于自由水的存在导致其电导明显增加，可能是高导层产生的原因之一。     

Dehydration Temperature of Serpentine at Elevated Temperatures and Pressures by Electrical Conductivity Method and Its Implications

Dehydration temperatures of serpentine were measured in the pressure range between 1.0GPa and 5.0GPa by using the electrical conductivity metod simultaneously at high temperatures and high pressures.The results show that with increasing pressure th dehydration temperature of antigorite increases slightly below 2.0GPa ,but drops markedly above2.0GPa .This strongly suggests that high pressure would favor the dehydration of serpentine minerals and the water released thereby would be an important source of fluids involved in magmatism in a subduction zone and mantle metasomatism,Meanwhile,the greatly enhanced electric conductivity in the presence of water may be one of the reasons underlying the occurrence of a high-conductivity zone in the lower crust.     

大别-苏鲁超高压变质带榴辉岩部分熔融的证据——微量元素和铅同位素

俯冲玄武质洋壳的部分熔融作用是一种重要的大陆生长作用，但是陆壳物质在俯冲过程中能否发生部分熔融缺少直接的证据。笔者利用已有的微量元素分配系数，讨论了岛弧玄武岩在脱水和部分熔融2种过程中微量元素行为和铅同位素演化的差异。Pb在2种过程中都属于不相容元素，但在脱水过程中其不相容性明显高于Rb、Ba、Th、U，而在熔融过程中则低于上述元素，在ω(Rb)/ω(Pb)-ω(Rb)、ω（Ba)/ω(Pb)-ω(Ba)、ω（Th)/ω(Pb)-ω(Th)、ω（U）／ω(Pb)-ω(U)相关图上2种过程的演化方向差别明显。此外，Pb和Th、U的相容性的差异也使得石榴石和绿辉石的单矿物铅同位素在2种过程中明显不同。在此基础上，结合大别－苏鲁榴辉岩的实测数据，认为大别－苏鲁榴辉岩可能部分是岛弧玄武岩部分熔融后的残余体，部分为单纯脱水的产物。大陆玄武质岩石在俯冲过程中也可能发生部分熔融作用。     

Compressional elastic wave velocities of serpentinized pyroxenite at high pressures and high temperatures and its geological significance

Elastic wave velocity measurement in rocks at high pressures and high temperatures plays a key role in researching the state, properties and movement of the earth interior materials. Nowadays dehydration is believed to be as one of the most important reasons responsible for the abnormality of seismic velocity (Kern, 1982; Ito, 1990; Christensen, 1989; Popp, Kern, 1993; SONG, et al, 1996; ZHOU, 1998; ZHAO, et al, 1996). Geophysical, geochemical and mineralogical data have revealed that on…     

Water-weakened lower crust and its role in the concentrated deformation in the Japanese Islands

The nature and origin of the concentrated deformation zone along the Japan Sea coast (NKTZ: Niigata-Kobe tectonic zone) was investigated by carefully analyzing the GPS data and qualitatively modeling the lower crust in NKTZ. It was concluded that this deformation zone is not a plate boundary between the Amurian plate (AMU) and the North America plate but is rather an internal deformation zone near the eastern margin of AMU. The data previously obtained on the conductivity anomalies in the lower crust and the ³He/⁴He ratios suggest that the concentrated deformation in NKTZ results from the lower crust in NKTZ being weakened by a high water content. The high water content is thought to result from the dehydration of subducting slabs. NKTZ has a higher water content in the lower crust than other regions do because there is no Philippine Sea plate (PHS) seismic slab beneath NKTZ. In other regions, it is estimated that the mantle wedge above the seismic Philippine Sea slab prevents the water dehydrated from the slab from rising to the lower crust, and that the lithosphere within PHS itself prevents the water dehydrated from the Pacific plate from rising up through it.     

Characterization of some Egyptian serpentinites used as ornamental stones

Egypt is characterized by wide occurrence of serpentinites, particularly in the central and southern parts of Eastern Desert. There are several cooperate factors that affect the serpentinites used as ornamental stones. These factors involve mineralogical characteristics （including mineral composition and microstructure parameter）, physical properties and mechanical properties. Antigorite is an essential serpentinite mineral, with a minor amount of chrysotile. Talc, carbonates （magnesite and dolomite） and tremolite are the main associated minerals. Quality and quantity of associated minerals such as talc and carbonates （dolomite and magnesite） affect the properties of serpentinites used as ornamental stones. Carbonates are resistant to weathering but suffer from acidic cleaning agents in interior use, whereas serpentinites with a high content of talc used on external faces undergo an increase in volume and a consequent rapid degradation. Studied serpentinites are characterized by relatively small grain size with foliated texture, low water absorption, low porosity, and high abrasion resistance. In the samples studied the uniaxial compressive strength （UCS） varies between 89 and 189 MPa, with an average of 152 MPa. According to the classification of Bell （1992）, sample No. B8 is very high in strength while the rest high in strength.     

大别山双河长英质片麻岩在1.0～4.5GPa下的结晶实验及其地质意义

在７５０～１２００℃、１．０～４．５ＧＰａ条件下对取自于大别山双河的长英质片麻岩进行了重结晶实验。在７５０℃时,随压力增加矿物生成顺序为：角闪石在１．７５ＧＰａ时出现,２．５ＧＰａ时消失;黑云母在１．７５ＧＰａ时通过水化反应生成多硅白云母;绿帘石可以稳定到＞３．５ＧＰａ,在４ＧＰａ时转变成硬柱石;石榴石和绿辉石在１．５ＧＰａ时开始出现,而斜长石在１．７５ＧＰａ时消失;石英在３ＧＰａ时转变为柯石英。这表明角闪岩相与榴辉岩相的转变发生在１．５～１．７５ＧＰａ,并且,榴辉岩相可进一步划分出角闪榴辉岩相、柯石英榴辉岩相和硬柱石榴辉岩相等,它们分别指示不同的压力区间。多硅白云母是长英质岩石在高压－超高压条件下的主要共生矿物,其水化反应特性及结构水的保存致使陆壳在深俯冲过程中未发生明显的脱水作用,这是大别山碰撞带未能形成钙碱性岩浆弧的主要原因。     

Blueschist blocks at Mochimaru in the Tari-Misaka ultramafic complex: Their petrologic characteristics and significance

Blueschist tectonic blocks occur in serpentinites at Mochimaru, Hiroshima Prefecture, Southwest Japan. They contain alkali amphibole coexisting with pumpellyite and chlorite, with or without calcic amphibole. Textural and chemical analyses reveal that the blueschists, together with other mafic schists, have similar metamorphic history. After their capture by serpentinites and before the emplacement of the serpentinites into the present geological position, the tectonic blocks were subjected to high P/T metamorphism around the boundary between the blueschist and pumpellyite–actinolite facies. The amphiboles formed by this metamorphism change from tremolite through glaucophane to ferroglaucophane with increasing FeO/MgO of whole rock compositions. The P–T conditions are estimated to be within 200–350°C and 5–7 kbar. These are higher P/T conditions than those of the regional metamorphism of Southwest Japan. The difference in the P–T conditions implies differences in tectonic situation and timing of metamorphism between the blocks and regional metamorphic rocks. In addition, the high P/T metamorphism of the tectonic blocks probably occurred in more reducing environments than the regional metamorphism. Because the ferric/ferrous iron ratios of the tectonic blocks are within a narrow range, it is stressed that oxygen fugacity was externally buffered during the high P/T metamorphism by the serpentinization process of the host ultramafic rocks. The reducing effect of serpentinization is common throughout the high P/T metamorphic terranes of Southwest Japan.     

脱水对条斑紫菜叶状体psbA和psbD基因表达量的影响

从处于不同脱水复水阶段的条斑紫菜(Porphyra yezoensis Ueda)叶状体中提取总RNA,用荧光定量PCR技术检测条斑紫菜不同脱水和复水过程中psbA和psbD基因的转录水平上的相对表达量的变化.实验结果表明,psbA和psbD基因转录水平上的相对表达量的变化趋势相似但变化幅度不一致.在相对含水量约为71...