Spectral emissivity measurements of Mercury's surface indicate Mg- and Ca-rich mineralogy, K-spar, Na-rich plagioclase, rutile, with possible perovskite, and garnet     

A.L. Sprague  K.L. Donaldson Hanna  J. Helbert  J.B. Warell 《Planetary and Space Science》2009,57(3):364-383

Mid-infrared 2-D spectroscopic measurements from 8.0 to 12.7 μm of Mercury were taken using Boston University's Mid-Infrared Spectrometer and Imager (MIRSI) mounted on the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, 7-11 April 2006. Measurements reported here cover radar bright region C, a dark plains region west of Caloris Basin, and the interior of Caloris Basin. By use of spectral deconvolution with a large spectral library composed of many mineral compositions and grain size separates, we fitted, or “unmixed”, the Mercury spectra. We find mineral suites composed of magnesium-rich orthopyroxene and olivine, Ca-, Mg-, Na-rich clinopyroxene, potassium feldspar, and Na-bearing plagioclase feldspar. Both Ca- and Mg-rich garnet (pyrope and grossular, respectively) are apparently present in small amounts. Opaque minerals are required for spectral matching, with rutile (TiO₂) repeatedly providing the “best fit”. However, in the case of the radar bright region C, perovskite also contributed to a very good fit. Caloris Basin infill is rich in both potassium feldspar and Na-rich plagioclase. There is little or no olivine in the Caloris interior smooth plains. Together with the high alkali content, this indicates that resurfacing magmas were low to intermediate in SiO₂. Data suggest the dark plains exterior to Caloris are highly differentiated low-iron basaltic magmas resulting in material that might be classified as oligoclase basalts.  相似文献   

湖北铜绿山矿床石英闪长岩的矿物学及Sr-Nd-Pb同位素特征   总被引：11，自引：8，他引：3  

赵海杰  毛景文  向君峰  周振华  魏克涛  柯于富 《岩石学报》2010,26(3):768-784

铜绿山是长江中下游鄂东南矿集区最重要的、大型夕卡岩型Cu-Fe(Au)矿床。本文对该矿区中与成矿密切的石英闪长岩进行了详细的矿物成分、地球化学及Sr-Nd-Pb同位素研究。结果表明:岩石中斜长石主要为更长石(An=21～31);角闪石贫Ti(0.2),高Mg/(Mg+Fe)(0.5),属于富镁角闪石;而黑云母为镁质黑云母。岩石的地球化学具有高硅(58.86%～67.71%),富碱(Na2O+K2O=5.67%～9.63%),富集轻稀土元素(LREE)和大离子亲石元素(LILE),并强亏损元素Nb、Ta、Ti等特征。岩石的(87Sr/86Sr)i为0.7055～0.7069,εNd(t)为-7.65～-3.44;(206Pb/204Pb)i=17.66～18.00,(207Pb/204Pb)i=15.49～15.56,(208Pb/204Pb)i=37.73～38.19。矿物成分、地球化学和同位素特征说明,铜绿山岩体与阳新岩体为同源岩浆的产物,源区为深度大于40km的富集地幔,经下地壳的混染及分离结晶作用形成。岩浆熔体形成的温度应大于889℃。角闪石和黑云母的温度计估算岩浆结晶温度分别为650～800℃和500～630℃,黑云母开始结晶温度略低于角闪石结晶结束温度,压力为1.49kbar,对应侵位深度约4.9km。岩浆具有利于Cu、Fe、Au等成矿元素进入熔体的条件,可能与板块俯冲作用相关。  相似文献   

都龙锡锌矿床绿泥石特征及其成矿意义   总被引：4，自引：1，他引：3  

廖震  刘玉平  李朝阳  叶霖  刘世荣  郑文勤 《矿床地质》2010,29(1):169-176

都龙锡锌超大型矿床是中国第三大锡石硫化物矿床,其中的绿泥石化相当普遍,并与矿化关系密切。本文在岩矿鉴定基础上,利用电子探针对绿泥石进行了微区化学成分研究。研究结果表明,该矿床绿泥石为富铁种属的假鳞绿泥石、鲕绿泥石、蠕绿泥石(铁绿泥石)及铁镁绿泥石,指示形成于还原环境;绿泥石为泥质岩或铁镁质岩受热液交代蚀变的产物,绿泥石结构的离子置换主要体现为Fe对Mg的置换,反映其形成与含铁建造有关;绿泥石的形成温度为231～304℃,平均为269℃,属于中-低温范围。绿泥石的形成机制主要表现为溶蚀-结晶、溶蚀-迁移-沉淀结晶2种。绿泥石可能与锡成矿同期形成,其与矿石矿物的生成关系表明,燕山期岩浆活动对都龙矿床的叠加改造作用显著。  相似文献   

皖赣相邻鄣公山地区新元古代地壳组成及造山过程   总被引：5，自引：1，他引：4  

张彦杰  周效华  廖圣兵 《地质学报》2010,84(10):1401-1427

摘要：皖赣相邻的鄣公山地区位处江南造山带北缘,区内广布一套厚度巨大、低绿片岩相变质的以泥砂质细碎屑岩为主含少量火山物质的复理石建造体,大量高精度同位素测年数据显示,其形成于821-840Ma间的新元古代早期,以景德镇-鄣源-伏川区域断裂带为界,南部为形成于大陆边缘拉张构造环境下的溪口岩群;北部的双桥山群火山-陆缘细碎屑岩系是与岛弧有关盆地中的沉积物。北东-南西向展布于鄣公山北坡的蚀变枕状-块状基性火山熔岩、辉长岩、辉绿岩等基性岩类呈构造碎块或碎片产出于溪口岩群火山-陆缘细碎屑岩组成的复理石基质中,通过对其产出地质特征及岩石地球化学特征等的分析,认为其形成于低速扩张的陆缘小洋盆扩张脊环境,具初始洋壳基性岩特征,属皖南伏川蛇绿岩西延组成部分。呈夹层产出于双桥山群地层中的大量玻屑晶屑凝灰岩及少量安山岩、流纹岩等具相似的岩石地球化学特征,属中钾钙碱性岩石系列,形成于大陆边缘火山弧构造环境。综合区内沉积事件、岩浆事件和构造事件等,提出皖赣相邻区新元古代经历了古扬子板块东南缘裂开－陆缘小洋盆有限俯冲－弧陆碰撞造山－造山期后陆壳裂陷沉积的构造演化过程。  相似文献   

The shift between worlds of production as an innovative process in the wine industry in Castile and Leon (Spain)     

José Luis Sánchez-Hernández  Javier Aparicio-Amador  José Luis Alonso-Santos 《Geoforum》2010,41(3):469-478

This article draws on the theory of conventions and the concept of worlds of production for an interpretation of the transformations of a regional production system over several decades. Wine production in the Spanish region of Castile and Leon has shifted from a world of local and interpersonal production (prevailing before 1960) to the current preferred orientation towards quality markets, having passed through an intermediate phase (1960-1980) of table and bulk wines industrial production. Recently, indications have appeared of a return to an interpersonal and neo-artisanal production on the part of prestigious winemakers who distribute their wines to selected international clients. This path is the result of a gradual modification of the dominant conventions of the business, which has experienced a spectacular development in Castile and Leon, whose wines are now appreciated in many foreign markets. This evolution of conventions may be interpreted as an innovative process maintained to challenge the trends and demands of the market. But this argument does not explain how conventions change and how these changes spread along the production chain. Therefore, this article discusses the contribution of three factors to this shift across different worlds of wine production: organization of the production chain; regulations regarding the protection of food differentiated according to its geographic origin; and the setting up of a regional innovation system which supports the wine sector.  相似文献   

中国大骨节病区水环境化学组分特征研究综述   总被引：2，自引：0，他引：2       下载免费PDF全文

刘国许模童憬赵瑞  李明波 《中国地质》2010,37(3):571-576

大骨节病发病机理复杂,病因研究没有取得统一的认识,但多数学者认为大骨节病与病区饮水存在关系。本文查阅了近30年大骨节病的研究文献,从常量组分、微量元素、有机物三方面总结病区水化学组分研究成果进行了综述。认为国内外学者大骨节病的研究方面已取得很多成果,但仍有许多不同看法和争议,尚需继续深入研究。  相似文献   

Eclipsing binary Trojan asteroid Patroclus: Thermal inertia from Spitzer observations     

Michael Mueller  Franck Marchis  Joshua P. Emery  Stefano Mottola  Jérome Berthier 《Icarus》2010,205(2):505-515

We present mid-infrared observations of the binary L5-Trojan system (617) Patroclus-Menoetius before, during, and after two shadowing events, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. For the first time, we effectively observe changes in asteroid surface temperature in real time, allowing the thermal inertia to be determined very directly. A new detailed binary thermophysical model is presented which accounts for the system’s known mutual orbit, arbitrary component shapes, and thermal conduction in the presence of eclipses.We obtain two local thermal-inertia values, representative of the respective shadowed areas: and . The average thermal inertia is estimated to be , potentially with significant surface heterogeneity. This first thermal-inertia measurement for a Trojan asteroid indicates a surface covered in fine regolith. Independently, we establish the presence of fine-grained (<a few μm) silicates on the surface, based on emissivity features near 10 and similar to those previously found on other Trojans.We also report V-band observations and report a lightcurve with complete rotational coverage. The lightcurve has a low amplitude of peak-to-peak, implying a roughly spherical shape for both components, and is single-periodic with a period equal to the period of the mutual orbit, indicating that the system is fully synchronized.The diameters of Patroclus and Menoetius are 106±11 and , respectively, in agreement with previous findings. Taken together with the system’s known total mass, this implies a bulk mass density of , significantly below the mass density of L4-Trojan asteroid (624) Hektor and suggesting a bulk composition dominated by water ice.All known physical properties of Patroclus, arguably the best studied Trojan asteroid, are consistent with those expected in icy objects with devolatilized surface (extinct comets), consistent with what might be implied by recent dynamical modeling in the framework of the Nice Model.  相似文献   

Negative ions in the Enceladus plume     

A.J. Coates  G.H. Jones  G.R. Lewis  A. Wellbrock  D.T. Young  R.E. Johnson  T.W. Hill 《Icarus》2010,206(2):618-622

During Cassini’s Enceladus encounter on 12th March 2008, the Cassini Electron Spectrometer, part of the CAPS instrument, detected fluxes of negative ions in the plumes from Enceladus. It is thought that these ions include negatively charged water group cluster ions associated with the plume and forming part of the ‘plume ionosphere’. In this paper we present our observations, argue that these are negative ions, and present preliminary mass identifications. We also suggest mechanisms for production and loss of the ions as constrained by the observations. Due to their short lifetime, we suggest that the ions are produced in or near the water vapour plume, or from the extended source of ice grains in the plume. We suggest that Enceladus now joins the Earth, Comet Halley and Titan as locations in the Solar System where negative ions have been directly observed although the ions observed in each case have distinctly different characteristics.  相似文献   

Dynamics of the Hungaria asteroids     

Andrea Milani  Zoran Kne?evi?  Alberto Cellino 《Icarus》2010,207(2):769-794

To try to understand the dynamical and collisional evolution of the Hungaria asteroids we have built a large catalog of accurate synthetic proper elements. Using the distribution of the Hungaria, in the spaces of proper elements and of proper frequencies, we can study the dynamical boundaries and the internal structure of the Hungaria region, both within a purely gravitational model and also showing the signature of the non-gravitational effects. We find a complex interaction between secular resonances, mean motion resonances, chaotic behavior and Yarkovsky-driven drift in semimajor axis. We also find a rare occurrence of large scale instabilities, leading to escape from the region. This allows to explain the complex shape of a grouping which we suggest is a collisional family, including most Hungaria but by no means all; we provide an explicit list of non-members of the family. There are finer structures, of which the most significant is a set of very close asteroid couples, with extremely similar proper elements. Some of these could have had, in a comparatively recent past, very close approaches with low relative velocity. We argue that the Hungaria, because of the favorable observing conditions, may soon become the best known sub-group of the asteroid population.  相似文献   

Chang’E-1 gamma ray spectrometer and preliminary radioactive results on the lunar surface     

Meng-Hua Zhu  Tao Ma 《Planetary and Space Science》2010,58(12):1547-1554

The Chang’E-1(CE-1) spacecraft took a gamma-ray spectrometer (hereafter, CGRS) to detect the element distributions on the lunar surface in a circular, 200 km altitude, polar orbit with approximately 2 h periodicity. CGRS consists of two large CsI(Tl) crystals as the main and anticoincidence detectors. The large CsI crystal of CGRS has a higher detector effective area than other lunar gamma ray spectrometers. For its 1-year mission, gamma ray spectra including many peaks of major elements and trace elements on the lunar surface have been measured by CGRS. Global measurement within 0.55-0.75 MeV is given here to describe the distribution of radioactive composition (e.g., uranium and thorium) on the lunar surface. Although CGRS has a lower energy resolution that cannot separate the uranium peak from others in this energy region, 609 keV uranium gamma ray line dominates the shape of the spectrum in this energy region. Therefore, the radioactive map can indirectly describe the uranium distribution on the lunar surface. The radioactive map shows that the higher radiation is concentrated in the Procellarum KREEP Terrene (PKT) on the nearside with an oval shape. The secondary high-radiation is located in South Pole-Aitken (SPA) basin. Lunar highlands have lower concentration. The relationship between radiation and topography displays different linear correlations for lunar highlands and SPA basin, which imply the different processes for these two regions.  相似文献