岩浆作用过程的一种有效判别方法──(1/C_i)-(1/C_j)和(或)lgC_i-lgC_j图解法     

石林  黄智龙 《矿物学报》1997,(2)

本文利用一种新的方法和（或）lgCi－lgCi图解法，明显地区分出地幔平衡部分熔融作用和岩浆分离结晶作用。并以亚速尔群岛中Terceira岛火山岩和汉诺坝玄武岩的实际资料验证了所推导的方法。  相似文献   

Crystallization of melts, pegmatite intrusion and the Inverian retrogression of the Scourian complex, north-west Scotland   总被引：2，自引：0，他引：2  

I. CARTWRIGHT 《Journal of Metamorphic Geology》1988,6(1):77-93

Abstract Partial melting of tonalitic gneisses in the 2.7 Ga Badcallian granulite facies metamorphic episode in the Scourian complex of north-west Scotland produced a suite of granitic to trondhjemitic liquids. On cooling and excavation of the complex, these melts underwent fractional crystallization and the residual liquids eventually became water saturated. Comparison with experimental data suggests that water saturation would have occurred in these melts at around 620–700°C. From the retrograde P–T -time path followed by the complex it is estimated that H₂O-dominated fluids were exsolved from these melts at c. 2.5 Ga. It is proposed that these fluids were the cause of the 2.5 Ga Inverian retrogression of the Scourian complex and that water-saturated melts formed during the crystallization of the leucogneisses were intruded as a suite of pegmatites. The timing of pegmatite intrusion is consistent with this proposition as are the temperature estimates, timing, distribution and nature of the Inverian phase of metamorphism. It is likely that the crystallization of melts is an important process in bringing about hydrous retrogressive metamorphic episodes in a number of other basement terrains, such as West Greenland and Australia.  相似文献   

湖南千里山花岗岩的岩石学和地球化学研究   总被引：2，自引：0，他引：2  

李忠文  崔彬  匡跃求 《岩石矿物学杂志》1987,6(1):10-18

本文从岩石学、岩石化学等方面详细研究了湘南东坡矿田内的花岗岩体,认为岩体分四次侵入就位。前三次侵入岩体在岩体的产状、岩石的矿物成分、化学成分及稀土元素和其他微量元素的分配上都具有明显的相同演化趋势,表明它们是同源岩浆分离结晶作用的产物,而第四次侵入岩体则不符合这一演化趋势,表明与前三者不是同源岩浆产物,根据其产状特征,可能来自更深的位置。不同期次的侵入体,具有不同的矿化特征,从而构成本矿田特有的成矿模式。  相似文献   

从中国东部若干重要矿区看花岗岩类的成矿专属性     

张师 《地球科学》1985,(2)

本文着重讨论中国东部与铁、铜、钨、相及锡矿床有关的花岗岩类的岩石化学特征:铁矿成矿母岩通常为SiO_2 52—63%,Fe_2O_3 FeO 5.2—10%,K_2O Na_2O 5—10%。正常系列。S=62—72,b=10—20,σ=3—5。当PH_2O=500～1000巴时,初始结晶温度≥820°C。铜矿成矿母岩通常为SiO_2 61—70%,Fe_2O_3 FeO 2—5.2%,K_2O Na_2O5—7％。正常或铝过饱和系列。S=70—80.5,b=6—12,σ≤3。当PH_2O=500—1000巴时,初始结晶温度为780—820°C。钨、钼和锡矿成矿母岩SiO_2 70—77%,Fe_2O_3 FeO<5％,K_2O Na_2O 7—10%。铝过饱和系列。S=77—83,b=1—9,σ≤3。当PH_2O=300—1000巴时,初始结晶温度<780°C。  相似文献   

黑云母温度计能否用于估计花岗质侵入岩的结晶温度？     

徐鸿雪  汪洋 《岩石矿物学杂志》2024,43(1):37-46

为了探讨黑云母温度计是否适用于估计花岗质侵入岩的结晶温度,汇编了国内外典型花岗质侵入体的岩石化学和矿物化学数据,利用Henry等(2005)的黑云母Ti饱和温度计、Li 和Zhang (2022)的黑云母全组分温度计估算了岩浆温度,并与Shao等(2020)的锆饱和温度计估算结果进行了对比。结果表明,黑云母Ti饱和温度计估算的温度比锆饱和温度计和黑云母全组分温度计低50~200℃,因此认为黑云母Ti饱和温度计并不适用于估算花岗质侵入岩的结晶温度,而黑云母全组分温度计可以复现S型和I型花岗岩的锆饱和温度计结果。  相似文献   

黑龙江省虎林市幅重磁场特征及其地质解释   总被引：1，自引：0，他引：1  

林泽付  薛进  杨恕  吴东国 《世界地质》2004,23(4):397-401

以区域地质资料和物性资料为依据，对黑龙江省虎林市幅重磁场特征进行了综合分析。根据航磁△T异常以及布格异常平面等值线展布特点，对该区的杂乱磁场区、线性磁场区和平稳磁场区进行了相关的地质解释，描述了30条断裂构造带及其重力场特征；结合重力异常和航磁异常等综合资料，按结晶基底起伏形态，将虎林盆地划分为4个隆起、3个凹陷共7个构造单元。  相似文献   

Partial Crystallization of Mid-Ocean Ridge Basalts in the Crust and Mantle   总被引：2，自引：2，他引：2  

HERZBERG  CLAUDE 《Journal of Petrology》2004,45(12):2389-2405

Pressures at which partial crystallization occurs for mid-oceanridge basalts (MORB) have been examined by a new petrologicalmethod that is based on a parameterization of experimental datain the form of projections. Application to a global MORB glassdatabase shows that partial crystallization of olivine + plagioclase+ augite ranges from 1 atm to 1·0 GPa, in good agreementwith previous determinations, and that there are regional variationsthat generally correlate with spreading rate. MORB from fast-spreadingcenters display partial crystallization in the crust at ridgesegment centers and in both mantle and crust at ridge terminations.Fracture zones are likely to be regions where magma chambersare absent and where there is enhanced conductive cooling ofthe lithosphere at depth. MORB from slow-spreading centers displayprominent partial crystallization in the mantle, consistentwith models of enhanced conductive cooling of the lithosphereand the greater abundance of fracture zones through which theypass. In general, magmas that move through cold mantle experiencesome partial crystallization, whereas magmas that pass throughhot mantle may be comparatively unaffected. Estimated pressuresof partial crystallization indicate that the top of the partialmelting region is deeper than about 20–35 km below slow-spreadingcenters and some ridge segment terminations at fast-spreadingcenters. KEY WORDS: MORB; olivine gabbro; partial crystallization; partial melting; ridge segmentation; fracture zones; crust; mantle; lithosphere  相似文献   

长白山天池火山岩浆演化——来自主矿物成分的证据   总被引：10，自引：6，他引：10  

李霓 樊祺诚孙谦  张文兰 《岩石学报》2004,20(3):575-582

长白山天池火山岩的主要矿物成分为橄榄石、辉石、长石和铁钛氧化物，经电子探针测试，其成分变化特征明显，自造盾阶段一造锥阶段一全新世喷发，橄榄石中铁含量增加，一直达到铁橄榄石的端元组分；单斜辉石中铁质和钠质含量增加；长石则从基性的拉长石向含钾、钠渐高的歪长石和透长石演化；铁钛氧化物含量则明显减少。三阶段斑晶矿物成分的变化反映了天池火山近200万年来岩浆演化的完整系列，符合分离结晶作用的演化趋势。  相似文献   

新疆大卡拉苏花岗伟晶岩锥状绿柱石矿物特征   总被引：1，自引：0，他引：1  

蒋文程  段焕春 《矿产与地质》2003,17(3):222-224

在自然界中绿柱石多为柱状，往往呈杂乱无序状晶出，锥状绿柱石非常少见。大卡拉苏花岗伟晶中的六方锥状绿柱石，垂直花岗伟晶岩脉壁定向晶出，与熔浆期后钠质交代作用关系密切。  相似文献   

Petrochemistry of Volcanic Rocks in the Hishikari Mining Area of Southern Japan, with Implications for the Relative Contribution of Lower Crust and Mantle-derived Basalt     

Takahiro Hosono  Takanori Nakano 《Resource Geology》2003,53(4):239-259

Abstract. This study presents the petrographical, mineralogical, and geochemical characteristics of Late Pliocene‐Pleistocene volcanic rocks distributed in the Hishikari gold mining area of southern Kyushu, Japan, and discusses their origin and evolution. The Hishikari volcanic rocks (HVR), on the basis of age and chemical compositions, are divided into the Kurosonsan (2.4–1.0 Ma) and Shishimano (1.7–0.5 Ma) Groups, which occur in the northern and southern part of the area, respectively. Each group is composed of three andesites and one rhyodacite. HVR are characterized by high concentrations of incompatible elements compared with other volcanic rocks in southern Kyushu, and have low Sr/Nd and high Th/U, Th/Pb, and U/Pb ratios compared with typical subduction‐related arc volcanic rocks. Modal and whole‐rock compositions of the HVR change systematically with the age of the rocks. Mafic mineral and augite/hypersthene ratios of the andesites decrease with decreasing age in the Kurosonsan Group, whereas in the Shishimano Group, these ratios are higher in the youngest andesite. Similarly, major and trace element compositions of the younger andesites in the former group are enriched in felsic components, whereas in the latter group the youngest andesite is more mafic than older andesites. Moreover, the crystallization temperature of phenocryst minerals decreases with younger age in the former group, whereas the opposite trend is seen in the latter group. Another significant feature is that rhyodacite in the Shishimano Group is enriched in felsic minerals and incompatible elements, and exhibits higher crystallization temperatures of phenocryst minerals than the rhyodacite of the Kurosonsan Group. Geochemical attributes of the HVR and other volcanic rocks in southern Kyushu indicate that a lower subcontinental crust, characterized by so‐called EMI‐type Sr‐Nd and DUPAL anomaly‐like Pb isotopic compositions, is distributed beneath the upper to middle crust of the Shimanto Supergroup. The HVR would be more enriched in felsic materials derived from the lower crust by high‐alumina basaltic magma from the mantle than volcanic rocks in other areas of southern Kyushu. The Kurosonsan Group advanced the degree of the lower crust contribution with decreasing age from 51 %, through 61 and 66 % to 77 %. In the Shishimano Group, the younger rhyodacite and andesite are derived from hotter magmas with smaller amounts of lower crust component (58 and 57 %) than the older two andesites (65 % and 68 %). We suggest that the Shishimano rhyodacite, which is considered to be responsible for gold mineralization, was formed by large degree of fractional crystallization of hot basaltic andesite magma with less lower crustal component.  相似文献