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171.
以巢湖优势种铜绿微囊藻(Microcystis aeruginosa)和鱼腥藻(Anabaena sp.)为研究对象,研究不同温度(35、25和10℃)对这两种藻生长特性和胞外有机物产生的影响.结果表明,温度对铜绿微囊藻和鱼腥藻的藻细胞密度、碱性磷酸酶活性和胞外有机物浓度影响显著.25℃是铜绿微囊藻和鱼腥藻最适宜的生长温度,最高细胞密度分别达到3.12×107cells/ml和2.03×107 cells/ml.不同温度下两种藻的碱性磷酸酶活性特征,证实了高温对鱼腥藻生长的抑制和低温对铜绿微囊藻生长的抑制.胞外有机物释放总量受蓝藻生物量和单位细胞有机物释放速率的影响.铜绿微囊藻的溶解性有机碳和胞外总多糖释放量在25℃最高,最大值分别为49.28和38.46 mg/L;而鱼腥藻在35℃时释放量最高,最大值分别为45.82和40.60 mg/L;10℃条件抑制了两种藻的生长及胞外有机物的释放.鱼腥藻胞外多糖含量在35℃培养条件下最高,而铜绿微囊藻在10℃条件下最高,说明不利的生长条件会促进蓝藻胞外多糖的分泌.三维荧光图谱分析结果表明,铜绿微囊藻和鱼腥藻胞外有机物以类蛋白质和类腐殖酸为主,温度主要影响藻细胞胞外有机物浓度,而对有机物种类组成没有影响. 相似文献
172.
P Alc A Temel A Gourgaud G Kieffer M.N Gündodu 《Journal of Volcanology and Geothermal Research》1998,85(1-4)
The Lower Pliocene volcanic rocks occurring in the Gölcük area of SW Turkey exhibit alkaline major element trends with a general potassic character. The development of volcanism can be divided into 2 major stages such as trachytic ancient lavas/domes and tephriphonolitic, trachyandesitic to trachytic Gölcük eruptions (ignimbrites, lava/dome extrusions, phreatomagmatic deposits, and finally, young domes). Volcanic rocks consist primarily of plagioclase, clinopyroxene (which ranges in composition from diopside to augite and are commonly zoned), biotite, and phlogopite. Amphibole phenocrysts are restricted to the pyroclastic deposits. Pseudoleucites are also seen only in the lava/dome extrusions. Oxides and apatites are common accessory phenocryst phases. As would be expected from their potassic–alkaline nature, the volcanic rocks of the Gölcük area contain high amounts of LILE (Ba, Sr, Rb and K), LREE, and Zr. Concentrations of compatible elements such as Cr, Ni and V are very low, possibly indicating fractionation of olivine and clinopyroxene. Correlation of SiO2, Rb/Sr and MgO with 87Sr/86Sr (0.703506–0.704142) exhibit an increasing trend in the direction of crustal contamination. However, the isotopic compositions of Sr are not as high to indicate a high level of crustal contamination. Geochemical data are consistent with the derivation of Gölcük volcanic rocks from a metasomatized and/or enriched lithospheric mantle source during crustal extension in the area. This metasomatism was probably occurred by fluids released from the northward subduction between African and Eurasian plates during Tertiary, as the Gölcük volcanic rocks display features of island-arc magmas with having high Ba/Nb (>28) ratios, and Nb and Ti depletions. Lower Pliocene volcanism in the Gölcük was response to extensional tectonics. 相似文献
173.
174.
水泉沟岩体为岩浆成因,岩体的侵位深度2~3km,侵位时代为印支期,划分为4种岩石组合.水泉沟岩体是一个钾质-高钾质的钙碱性、弱碱性和碱性岩石共存的杂岩体.岩石化学成分变异图解证明岩浆存在两种演化趋势,一是酸性演化趋势:辉石闪长岩→角闪二长岩(包括二长岩)→石英碱长正长岩→碱长花岗岩;二是碱性演化趋势:正长岩→霓辉正长岩→碱长正长岩.同时也探讨了这两种演化趋势的内在机理. 相似文献
175.
新疆阿尔金山地区元古宙超钾质碱性岩的发现 总被引:1,自引:0,他引:1
阿尔金山巴什考供附近的超钾质碱性岩,以互层 状产出于斜长角 闪岩中。该超钾质碱性岩的SiO2含量为40.77%~40.98%,K2O + Na2O = 3.68%~6.94 %,K 2O/ Na2O为3.28~7.76,属于超钾质强碱性岩。岩石的稀土元素总量较高,介于70 5.68 ×10 -6~972.34×10-6之间,(La/Yb)n为37.27和43.53,Eu呈轻度负异常(Eu=0. 67~0.75),球粒陨 石标准化配分曲线显示轻稀土高度富集,重稀土低度富集特征,与典型的超钾质碱性岩配分 型式相似。该超钾质碱性岩的发现对研究该区壳幔相互作用及岩石圈演化具有深 远意义。 相似文献
176.
柴达木盆地周边火山岩十分发育,形成巨大的环状火山岩带。本文着重于研究火山岩的时空分布、产出古地理环境、以及它们的岩石学和岩石化学,以指出其产出构造环境和演化地质历史。根据火山成矿作用与铜多金属等矿产的密切关系和该区火山岩含矿特征,探讨了其含矿可能性。 相似文献
177.
Y. Vapnik V. V. Sharygin V. Samoilov Z. Yudalevich 《International Journal of Earth Sciences》2007,96(4):663-684
The basic and ultrabasic alkaline rocks of western Makhtesh Ramon, Israel crop out in numerous lava flows and subvolcanic
bodies. The rock suite is composed of tephrite, basanite, basanitic nephelinite, analcimite, olivine nephelinite, and melilite-olivine
nephelinite and in many outcrops is represented by glass-bearing varieties. Melt and fluid inclusions have been studied in
olivine, clinopyroxene, and plagioclase phenocrysts. The EP, SIMS and microthermometry methods were used for inclusion study.
The geochemical data obtained on glasses of melt inclusions (major, REE, trace elements, volatiles) are compared with the
data on whole-rock and groundmass glass compositions. The compositions of melt inclusions reflect the different stages of
rock crystallization: the initial products of crystallization are similar to whole-rock compositions whereas final portions
of melts are usually enriched in SiO2, Al2O3, and alkalis, and depleted in mafic components. The data on contemporaneous melt and CO2 inclusions were used for the evaluation of the P–T conditions of rock generation. The following parameters were obtained: tephrite: P = 6.3–7.7 kbar and T = 1,150–1,250°C; basanite: P = 6.6–9.2 kbar and T = 1,150–1,250°C; olivine and analcime-olivine nephelinite: P = 5.6–8.2 kbar and T = 1,150–1,250°C; melilite-olivine nephelinite: 4.0–5.4 kbar and T mainly between 1,150 and 1,200°C. Magma genesis was restricted to P–T conditions of spinel- and plagioclase-lherzolite fields. These data suggest the shallowest depth of magma genesis occurred
in Makhtesh Ramon compared to other occurrences of Early Cretaceous magmatism at the Middle East. Differences in the degree
of batch partial melting of the same source rocks best explain the diversity of the igneous suite in western Makhtesh Ramon. 相似文献
178.
辽西凌源河坎子碱性杂岩体地球化学特征及地质意义 总被引:18,自引:0,他引:18
分析测定了河坎子碱性杂岩体的稀土、微量元素和Sr、Nd、Pb同位素数据 ,对该杂岩体形成的构造背景、源区特征及意义进行了讨论。河坎子碱性杂岩体稀土元素总量较高 ,富集LREE和大离子亲石元素 ,Eu呈弱负异常或异常不明显 ,Nb、Ta、K、P、Ti和Y呈负异常 ,过渡族元素含量偏低。稀土和微量元素分布模式与辽东凤城碱性杂岩体相似。主侵入期 4个全岩加 1个黑云母样品的全岩矿物Rb_Sr等时线年龄为 2 2 1.4± 8.5 (2σ)Ma ,属于印支期碱性岩浆活动。该岩体的εSr(t)均为正值 ,平均 7.2 3,ISr=0 .70 4 77± 0 .0 0 0 15 ,εNd(t)均为负值。微量元素和Sr、Nd及Pb示踪同位素特征显示其源区与EMⅠ型富集地幔端员有关。河坎子碱性杂岩体地球化学特征不仅揭示了华北地台北缘东部上地幔在三叠纪时具有富集性 ,而且也显示了辽东地区比辽西地区更富集的特点。河坎子碱性杂岩体形成于板内拉张环境 ,岩浆作用以批式部分熔融占主导地位。 相似文献
179.
180.
The Origin of HIMU in the SW Pacific: Evidence from Intraplate Volcanism in Southern New Zealand and Subantarctic Islands 总被引:3,自引:0,他引:3
PANTER K. S.; BLUSZTAJN J.; HART S. R.; KYLE P. R.; ESSER R.; MCINTOSH W. C. 《Journal of Petrology》2006,47(9):1673-1704
This paper presents field, geochemical and isotopic (Sr, Nd,Pb) results on basalts from the Antipodes, Campbell and ChathamIslands, New Zealand. New 40Ar/39Ar age determinations alongwith previous KAr dates reveal three major episodes ofvolcanic activity on Chatham Island (8582, 4135,5 Ma). Chatham and Antipodes samples comprise basanite, alkaliand transitional basalts that have HIMU-like isotopic (206Pb/204Pb>20·320·8, 87Sr/86Sr <0·7033,143Nd/144Nd >0·5128) and trace element affinities(Ce/Pb 2836, Nb/U 3466, Ba/Nb 47). Thegeochemistry of transitional to Q-normative samples from CampbellIsland is explained by interaction with continental crust. Thevolcanism is part of a long-lived (100 Myr), low-volume, diffusealkaline magmatic province that includes deposits on the Northand South Islands of New Zealand as well as portions of WestAntarctica and SE Australia. All of these continental areaswere juxtaposed on the eastern margin of Gondwanaland at >83Ma. A ubiquitous feature of mafic alkaline rocks from this regionis their depletion in K and Pb relative to other highly incompatibleelements when normalized to primitive mantle values. The inversionof trace element data indicates enriched mantle sources thatcontain variable proportions of hydrous minerals. We proposethat the mantle sources represent continental lithosphere thathost amphibole/phlogopite-rich veins formed by plume- and/orsubduction-related metasomatism between 500 and 100 Ma. Thestrong HIMU signature (206Pb/204Pb >20·5) is consideredto be an in-grown feature generated by partial dehydration andloss of hydrophile elements (Pb, Rb, K) relative to more magmaphileelements (Th, U, Sr) during short-term storage at the base ofthe lithosphere. KEY WORDS: continental alkaline basalts; lithospheric mantle, mantle metasomatism; New Zealand; OIB, HIMU; Sr, Nd and Pb isotopes; West Antarctica 相似文献