Petrogenesis of the Dar al Gani (DaG) 1.1 Ma ejection-paired olivine-phyric shergottites and implications for ~470 Ma Martian volcanism     

Tarryn Aucamp  Geoffrey H. Howarth  Chad J. Peel  Gelu Costin  James M. D. Day  Petrus le Roux  James M. Scott  Ansgar Greshake  Rainer Bartoschewitz 《Meteoritics & planetary science》2023,58(11):1654-1676

The Dar al Gani (DaG) olivine-phyric shergottites share mineralogical and geochemical characteristics, which confirm that these meteorites are derived from a single source. Bulk trace elements (La/Yb—0.12), in situ maskelynite ⁸⁷Sr/⁸⁶Sr (~0.7014) and redox estimates (FMQ ~ −2) indicate derivation from a depleted, reduced mantle reservoir; identical to all ~470 Ma shergottites ejected at 1.1 Ma. The DaG shergottites have been variably affected by terrestrial alteration, which precipitated carbonate along fractures and modified bulk-rock fluid mobile (e.g., Ba) elements. Nonetheless, sufficient data are available to construct a multi-stage formation model for the DaG shergottites and other 1.1 Ma ejection-paired shergottites that erupted at ~470 Ma. First, partial melting of a depleted mantle source occurred at 1540 ± 20°C and 1.2 ± 0.1 GPa, equivalent to > ~100 km depth. Then, initial crystallization in a staging chamber at ~85 km depth at the crust–mantle boundary took place, followed by magma evolution and variable incorporation of antecrystic olivine ± orthopyroxene. Subsequently, crystallization of olivine phenocrysts and re-equilibration of olivine antecrysts occurred within an ascending magma. Finally, magmas with variable crystal loads erupted at the surface, where varied cooling rates produced a range of groundmass textures. This model is similar to picritic flood basalt magmas erupted on Earth.  相似文献   

地球上最大碰撞的地震成像     

Rainer Kind  许丽卿 《世界地震译丛》2011,(1)

几项大型地震试验正源源不断提供着印度构造板块在西藏之下俯冲的大尺度详尽图像。  相似文献   

Assessment of the Intake and the Pretreatment Design in Existing Seawater Reverse Osmosis (SWRO) Plants by Hasse Diagram Technique (HDT)     

Amos Bick  Rainer Bruggemann  Gideon Oron 《洁净——土壤、空气、水》2011,39(11):933-940

Seawater desalination is a rising technology intended to overcome water scarcity and is increasingly being used for the production of drinking water. A good quality pretreatment process is prominent to the successful operation of a Seawater Reverse Osmosis (SWRO) plant. The tasks of the intake and the pretreatment modules are to prevent fouling and to extend the lifetime of the reverse osmosis membranes. To practice the method of assessment design, 19 seawater plants with 11 different design strategies have been evaluated. The assessed strategies consist of: (i) Intake treatment, (ii) pretreatment aid (coagulation, flocculation, clarification), and (iii) pretreatment unit. Every possible combination of the design elements has been evaluated by a set of 15 attributes. The comparative evaluation has been conducted by Hasse diagram technique (HDT) using PyHasse software. The result of the HDT application includes 7 favorable incomparable design strategies. In order to solve the incomparability, the Condorcet–Kemeny–Young–Levenglick (C–K–Y–L) ranking procedure was additionally used and rendered the optimal design that is based on subsurface intake and membrane (ultrafiltration) pretreatment facilities. According to the results, both mathematical methods, i.e., the HDT in combination with the C–K–Y–L, procedure can be powerful and helpful tools to assist decisions concerning design strategies.  相似文献   

Ca-rich majorite derived from high-temperature melt and thermally stressed hornblende in shock veins of crustal rocks from the Ries impact crater (Germany)     

Volker Stähle  Rainer Altherr  Lutz Nasdala  Thomas Ludwig 《Contributions to Mineralogy and Petrology》2011,161(2):275-291

Shock veins up to 1.1 mm thick were found within non-porous lithic clasts from suevite breccia of the Nördlinger Ries impact structure. These veins were studied by optical microscopy in transmitted and reflected light and by scanning electron microscopy. In shocked amphibolites, two types of Ca-rich majorite occur within and adjacent to the veins. The first type crystallized from shock-induced melts within the veins. Si contents of these majorites suggest dynamic pressure of ~15–17 GPa, implying minimum temperatures in the range of ~2,150–2,230°C. The second type of majorite was formed adjacent to the shock veins within pargasitic hornblende. This majorite contains significant amounts of H₂O (0.7–0.9 wt%). Based on the textural setting, the shrinkage cracks and the chemical compositions of both phases, a solid-state mechanism is deduced for the hornblende to majorite phase transition. Both genetic types of Ca-rich majorite are described for the first time from a terrestrial impact crater. Along with stishovite, majorite constitutes the second silicate mineral displaying sixfold coordination of Si at Ries. Using micro-Raman spectroscopy, jadeite + coesite and jadeite + grossular were identified within local melt glasses of alkali feldspar and plagioclase composition, respectively. Stishovite aggregates, produced by solid-state reaction, along with shock-induced high-pressure melt glasses of almandine composition were also detected in shock veins of a garnet-cordierite-sillimanite restite. The quenched, homogeneous almandine glasses point to melting temperatures of more than ~2,500°C for the veins. Our findings demonstrate that terrestrial shock veins can give valuable information on shock-induced mineral transformations and transient high pressures of host rocks during a natural impact event.  相似文献   

Extreme alkali bicarbonate- and carbonate-rich fluid inclusions in granite pegmatite from the Precambrian Rønne granite,Bornholm Island,Denmark     

Rainer Thomas  Paul Davidson  Christian Schmidt 《Contributions to Mineralogy and Petrology》2011,161(2):315-329

Our study of fluid and melt inclusions in quartz and feldspar from granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark revealed extremely alkali bicarbonate- and carbonate-rich inclusions. The solid phases (daughter crystals) are mainly nahcolite [NaHCO₃], zabuyelite [Li₂CO₃], and in rare cases potash [K₂CO₃] in addition to the volatile phases CO₂ and aqueous carbonate/bicarbonate solution. Rare melt inclusions contain nahcolite, dawsonite [NaAl(CO₃)(OH)₂], and muscovite. In addition to fluid and melt inclusions, there are primary CO₂-rich vapor inclusions, which mostly contain small nahcolite crystals. The identification of potash as a naturally occurring mineral would appear to be the first recorded instance. From the appearance of high concentrations of these carbonates and bicarbonates, we suggest that the mineral-forming media were water- and alkali carbonate-rich silicate melts or highly concentrated fluids. The coexistence of silicate melt inclusions with carbonate-rich fluid and nahcolite-rich vapor inclusions indicates a melt-melt-vapor equilibrium during the crystallization of the pegmatite. These results are supported by the results of hydrothermal diamond anvil cell experiments in the pseudoternary system H₂O–NaHCO₃–SiO₂. Additionally, we show that boundary layer effects were insignificant in the Bornholm pegmatites and are not required for the origin of primary textures in compositionally simple pegmatites at least.  相似文献   

Investigation of the different binding edge sites for Zn on montmorillonite using P-EXAFS - The strong/weak site concept in the 2SPNE SC/CE sorption model     

Rainer Dähn  Bart Baeyens  Michael H. Bradbury 《Geochimica et cosmochimica acta》2011,75(18):5154-5168

The 2 site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) sorption model has been used over the past decade or so to quantitatively describe the uptake of metals with oxidation states from II to VI on 2:1 clay minerals; montmorillonite and illite. One of the main features in this model is that there are two broad categories of amphoteric edge sorption sites; the so called strong (S^SOH) and weak (S^W1OH) sites. Because of their different sorption characteristics, it was expected that the coordination environments of the surface complexes on the two site types would be different. Zn isotherm data on two montmorillonites, Milos and STx-1, were measured and modelled using the 2SPNE SC/CE sorption model. The results were used to define the most favourable experimental conditions under which Zn sorption was either dominated by the strong (S^SOH, ∼2 mmol kg⁻¹) or by the weak sites (S^W1OH, ∼40 mmol kg⁻¹). Highly oriented self-supporting films were prepared for polarised extended X-ray absorption fine structure (P-EXAFS) investigations.Montmorillonites often contain Zn incorporated in the clay matrix. The Zn bound in this form was quantified and the results from the analysis of the P-EXAFS spectra were taken into account in the interpretation of the spectra measured at low Zn loadings (∼2 mmol kg⁻¹) and medium Zn loadings (∼30 mmol kg⁻¹). The Zn spectra on the “strong sites” exhibited a pronounced angular dependency and formed surface complexes in the continuity of the Al-octahedral sheets at the montmorillonite edges. In contrast, the Zn “weak site” spectra showed only a weak angular dependency. The spectroscopic evidence indicates the existence of two distinct groups of edge surface binding sites which is consistent with a multi-site sorption model and in particular with the strong/weak site concept intrinsic to the 2SPNE S/CE sorption model.  相似文献   

Temperature Control on Soluble Reactive Phosphorus in the Lower Mississippi River?     

Shuiwang Duan  Rainer Amon  Thomas S. Bianchi  Peter H. Santschi 《Estuaries and Coasts》2011,34(1):78-89

Soluble reactive phosphorus (SRP) has recently been shown to be one of the limiting nutrients for the growth of phytoplankton in the northern Gulf of Mexico. We show here that during the past decade, SRP concentrations in the lower reaches of North America's largest river, the Mississippi River, were highest in summer and lowest in winter and positively correlated with water temperature. Upstream data showed this coupling to increase in a downstream trend in the Mississippi main stem. Water quality data analysis and phosphorus mass balances were conducted to examine the controls of this relationship. The results showed that the positive SRP–temperature correlation in the Mississippi River system was largely a result of gradual dilution of SRP-enriched upper Mississippi River waters, which contributed most to the Mississippi River during summer, by SRP-depleted waters from the Ohio and other tributaries. Particle buffering and organic matter mineralization might play a role in the observed SRP–temperature relationship, but their importance relative to tributary effects is not quantified. Future work on the seasonal dynamics of SRP in large river systems needs to consider the effects of both tributary dilution and in situ processes.  相似文献   

Fast exhumation of the ultrahigh-pressure Alpe Arami garnet peridotite (Central Alps, Switzerland): constraints from geospeedometry and thermal modelling     

B. Olker  R. Altherr  J. Paquin 《Journal of Metamorphic Geology》2003,21(4):395-402

Previous studies suggest that the metamorphic evolution of the ultrahigh‐pressure garnet peridotite from Alpe Arami was characterized by rapid subduction to a depth of c. 180 km with partial chemical equilibration at c. 5.9 Gpa/1180 °C and an initial stage of near‐isothermal decompression followed by enhanced cooling. In this study, average cooling rates were constrained by diffusion modelling on retrograde Fe–Mg zonation profiles across garnet porphyroclasts. Considering the effects of temperature, pressure and garnet bulk composition on the Fe–Mg interdiffusion coefficient, cooling rates of 380–1600 °C Myr^?1 for the interval from 1180 to 800 °C were obtained. Similar or even higher average cooling rates resulted from thermal modelling, whereby the characteristics of the calculated temperature‐time path depend on the shape and size of the hot peridotite body and the boundary conditions of the cooling process. The very high cooling rates obtained from both geospeedometry and thermal modelling imply extremely fast exhumation rates of c. 15 mm yr^?1 or more. These results agree with the range of exhumation rates (16–50 mm yr^?1) deduced from geochronological results. It is suggested that the Alpe Arami peridotite passively returned towards the surface as part of a buoyant sliver, caused as a consequence of slab breakoff.  相似文献   

A comparison of synthetic seismograms of core phases generated by the full wave theory and by the reflectivity method     

George L. Choy  Vernon F. Cormier  Rainer Kind  Gerhard Müller  Paul G. Richards 《Geophysical Journal International》1980,61(1):21-39

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中国西部壳幔结构与动力学过程及其对资源环境的制约:"羚羊计划"研究进展     

赵俊猛  张培震  张先康  Xiaohui YUAN  Rainer KIND  Robertvander HILST  甘卫军  孙继敏  邓涛  刘红兵  裴顺平  徐强  张衡  嘉世旭  颜茂都  郭晓玉  卢占武  杨小平  邓攻  琚长辉 《地学前缘》2021,28(5):230-259

为系统、深入地研究中国西部盆(盆地)、山(山脉)、原(高原)的壳幔结构与深部动力学过程,2003年我们提出并领导实施了“羚羊计划”(ANTILOPE-Array Network of Tibetan International Lithospheric Observation and Probe Experiments),在青藏高原先后完成了羚羊-I(ANTILOPE-I)到羚羊-IV(ANTILOPE-IV)4条二维宽频带台阵剖面,而在青藏高原东西构造结则实施了羚羊-V和羚羊-VI两个三维宽频带台阵探测。另外,我们将前期在准噶尔盆地、天山造山带、塔里木盆地、阿尔金造山带和柴达木盆地开展的九条综合地球物理观测剖面也纳入羚羊计划的总体框架中来。 通过“羚羊计划”的实施,我们在中国西部(包括西北部的环青藏高原盆山体系以及西南部的青藏高原)取得了大量的、高质量的、综合的第一手观测数据,获得了中国西部盆、山、原精细的壳幔结构,系统地揭示了中国西部盆山原的深部地球动力学过程。主要结论总结如下:确定了准噶尔盆地基底的结构与属性,优化了盆地的基底构造格架;建立了天山造山带“层间插入削减”新的陆内造山模式,揭示了印欧碰撞在天山岩石圈缩短44%的去向以及由洋-陆俯冲到陆-陆碰撞俯冲的转换机制;揭示了塔里木盆地、阿尔金造山带和柴达木盆地的盆山接触关系;获得了塔里木盆地顺时针旋转的深部几何学、运动学和动力学证据;确定了青藏高原之下印度板块与欧亚板块的碰撞边界;发现目前的青藏高原由南部的印度板块、北部的欧亚板块和夹持于二者之间的巨型破碎区——西藏“板块”构成,首次确定了各自的岩石圈底边界;修正了高原变形的两个端员模型;建立了深部构造对地表地形的制约关系;系统地揭示了印度板块沿喜马拉雅造山带俯冲的水平距离与俯冲角度的变化规律与控制因素。 “羚羊计划”以其巨大的观测网络与综合地球物理探测技术,采用地球物理学、地质学、地球化学等不同学科相结合的分析方法,揭示了印度板块俯冲、西藏巨型破碎区发育、塔里木板块顺时针旋转、西部水汽通道提前关闭、中国西北部干旱、沙漠化提前这一深部结构、动力学过程及其对地表地形、油气资源和环境变化的制约关系,推动了青藏高原地球系统科学理论的发展。  相似文献