TNOs are Cool: A Survey of the Transneptunian Region     

Thomas G. Müller  Emmanuel Lellouch  Hermann Böhnhardt  John Stansberry  Antonella Barucci  Jacques Crovisier  Audrey Delsanti  Alain Doressoundiram  Elisabetta Dotto  René Duffard  Sonia Fornasier  Olivier Groussin  Pedro J. Gutiérrez  Olivier Hainaut  Alan W. Harris  Paul Hartogh  Daniel Hestroffer  Jonathan Horner  Dave Jewitt  Mark Kidger  Csaba Kiss  Pedro Lacerda  Luisa Lara  Tanya Lim  Michael Mueller  Raphael Moreno  Jose-Luis Ortiz  Miriam Rengel  Pablo Santos-Sanz  Bruce Swinyard  Nicolas Thomas  Audrey Thirouin  David Trilling 《Earth, Moon, and Planets》2009,105(2-4):209-219

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well.  相似文献   

Behaviour of REE and mass balance calculations in a lateritic profile over chlorite schists in South Cameroon     

Veronique Kamgang Kabeyene Beyala  Estelle Ndome Effoudou Priso  Georges Emmanuel Ekodeck 《Chemie der Erde / Geochemistry》2009,69(1):61-13

An in situ weathering profile overlying chlorite schists in the Mbalmayo-Bengbis formations (South Cameroon) was chosen for the study of the behaviour of REE and the evaluation of geochemical mass balance. After physical and mineralogical studies, the chlorite schists and the undisturbed weathered materials were chemically analyzed for major elements (X-ray fluorescence and titrimetry) and REE (ICP-MS). The behaviour of the REE in the Mbalmayo weathering system was established in comparison with the REE of the reference parent rock. Mass balance calculations were applied to both major elements and REE. The mineralogy of the materials was determined with the aid of a Philips 1720, diffractometer. The chlorite schists of the Mbalmayo sector show low REE contents (Σ=153.44 ppm). These rocks are relatively rich in LREE (about 125 times the chondritic value) and relatively poor in HREE (about 20 times the chondritic value). The REE diagram normalized to chondrites shows a slightly split graph ((La/Yb)_N=6.18) with marked enrichment in LREE (LREE/HREE=9.50) in relation to HREE. Moreover, these spectra do not present any Ce anomaly, but a slightly positive Eu anomaly. The imperfectly evolved profile, whose materials are genetically linked, shows an atypical behaviour of REE. In effect, the LREE are more mobile than the HREE during weathering ((La/Yb)NASC<1) with weak Ce anomalies. This has been rarely reported in lateritic profiles characterized by higher HREE mobility than LREE during weathering processes with high Ce anomalies. This is either due to the difference in the stability of REE-bearing minerals, or to the weak acidic to basic pH conditions (6.70<pH<7.80), or even due to the average evolution of the weathering materials. The pathway of the REE along the profile is as follows: (1) leaching in the saprolites and summit of the profile, except for Ce, which precipitates very weakly in the nodular materials and the coarse saprolite materials, (2) at the base of the profile, solutions come in contact with chlorite schist formations, at this level, the pH increases (pH=7.79), HREE and a part of LREE partially void of Ce precipitate and (3) the other part of LREE precipitates further up in the profile. The geochemical mass balance calculations reveal that these elements are leached in the same phases as the relatively high Si, Al, K and Fe²⁺ contents.  相似文献   

Paleoproterozoic volcanic rocks in the southern margin of the North China Craton,central China:Implications for the Columbia supercontinent   总被引：1，自引：0，他引：1  

Changming Wang  Xinyu He  Emmanuel John M.Carranza  Chengmin Cui 《地学前缘(英文版)》2019,10(4):1543-1560

The volcanic rocks of the Xiong'er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia supercontinent during the Paleoproterozoic.In this study,to constrain the age of the Xiong'er volcanic rocks and identify its tectonic environment,we report zircon LA-ICP-MS data with Hf isotope,whole-rock major and trace element compositions and Sr-Nd-Pb-Hf isotopes of the volcanic rocks of the Xiong'er Group.The Xiong'er volcanic rocks mainly consist of basaltic andesite,andesite.dacite and rhyolite,with minor basalt.Our new sets of data combined with those from previous studies indicate that Xiong'er volcanism should have lasted from 1827 Ma to 1746 Ma as the major phase of the volcanism.These volcanics have extremely low MgO.Cr and Ni contents,are enriched in LREEs and LILEs but depleted in HFSEs(Nb,Ta,and Ti),similar to arc-related volcanic rocks.They are characterized by negative zircon ε_(Hf)_(t) values of-17.4 to 8.8,whole-rock initial ~(87)Sr/~(86)Sr values of 0.7023 to 0.7177 andε_(Nd)(t) values of-10.9 to 6.4.and Pb isotopes(~(206)Pb/~(204)Pb =14.366-16.431,~(207)Pb/~(204)Pb =15.106-15.371,~(208)Pb/~(204)Pb= 32.455-37.422).The available elemental and Sr-Nd-Pb-Hf isotope data suggest that the Xiong'er volcanic rocks were sourced from a mantle contaminated by continental crust.The volcanic rocks of the Xiong'er Group might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by oceanic subduction in the Archean.Thus,we suggest that the subduction-modified lithospheric mantle occurred in an extensional setting during the breakup of the Columbia supercontinent in the Late Paleoproterozoic,rather than in an arc setting.  相似文献   

Maximum Entropy and Random Forest Modeling of Mineral Potential: Analysis of Gold Prospectivity in the Hezuo–Meiwu District,West Qinling Orogen,China     

Zhang  Shuai  Xiao  Keyan  Carranza  Emmanuel John M.  Yang  Fan 《Natural Resources Research》2019,28(3):645-664

Natural Resources Research - This study tested and compared the mineral potential mapping capabilities of the random forest (RF) and maximum entropy (MaxEnt) algorithms using gold deposit...  相似文献   

3D Mineral Prospectivity Mapping with Random Forests: A Case Study of Tongling,Anhui, China     

Xiang  Jie  Xiao  Keyan  Carranza  Emmanuel John M.  Chen  Jianping  Li  Shi 《Natural Resources Research》2020,29(1):395-414

Natural Resources Research - In the past few decades, a variety of data-driven predictive modeling techniques has led to a dramatic advancement in mineral prospectivity mapping (MPM). The random...  相似文献   

Co-simulated Size Number: An Elegant Novel Algorithm for Identification of Multivariate Geochemical Anomalies     

Madani  Nasser  Carranza  Emmanuel John M. 《Natural Resources Research》2020,29(1):13-40

Natural Resources Research - Identification of geochemical anomalies is of particular importance for tracing the footprints of anomalies. This can be implemented by advanced techniques of...  相似文献   

Best practices for the use of meteorite names in publications     

Philipp R. Heck  Christopher Herd  Jeffrey N. Grossman  Dmitry Badjukov  Audrey Bouvier  Emma Bullock  Hasnaa Chennaoui‐Aoudjehane  Vinciane Debaille  Tasha L. Dunn  Denton S. Ebel  Ludovic Ferrire  Laurence Garvie  Jrme Gattacceca  Matthieu Gounelle  Richard Herd  Trevor Ireland  Emmanuel Jacquet  Robert J. Macke  Tim McCoy  Francis M. McCubbin  Takashi Mikouchi  Knut Metzler  Mathieu Roskosz  Caroline Smith  Meenakshi Wadhwa  Linda Welzenbach‐Fries  Toru Yada  Akira Yamaguchi  Ryan A. Zeigler  Michael Zolensky 《Meteoritics & planetary science》2019,54(7):1397-1400

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Compositional Balance Analysis: An Elegant Method of Geochemical Pattern Recognition and Anomaly Mapping for Mineral Exploration     

Liu  Yue  Carranza  Emmanuel John M.  Zhou  Kefa  Xia  Qinglin 《Natural Resources Research》2019,28(4):1269-1283

Natural Resources Research - Geochemical pattern recognition and anomaly mapping are always involved in the fields of environmental and exploration geochemistry. Principal component analysis (PCA)...  相似文献   

Modulating the Impacts of Stochastic Uncertainties Linked to Deposit Locations in Data-Driven Predictive Mapping of Mineral Prospectivity     

Parsa  Mohammad  Carranza  Emmanuel John M. 《Natural Resources Research》2021,30(5):3081-3097

Natural Resources Research - The operation of large-scale ore-forming processes triggers the development of neighboring mineral deposits of the same or related types in a metallogenic province....  相似文献   

‘Borehole Race’ and the Dilemma of Governing the ‘Ungoverned’: Understanding the Urban Political Ecology of Groundwater Exploitation in Nigeria     

Emmanuel M. Akpabio  Ekerette S. Udom 《社会与自然资源》2018,31(9):1030-1044

Groundwater exploitation is an essential aspect of the numerous processes of transforming the urban natural environment for human gains. We use the political ecology of borehole exploitation in Nigeria’s urban environment to understand the micro-and macro-level processes mediating the transformation and changes in urban “groundwater scape”. The fieldwork processes depend on field counting of borehole distribution, in-depth and semi-structured interviews, and a review of secondary literatures. We argue that the social and environmental changes arising from the exploitation of groundwater bespeak the active and continual manifestation of the interplay of combustible interests and power friction among institutional agents within the permissible range of the natural environment. Such dynamic power relations engender a pattern of socio-natural transformation consistent with Swyngedouw’s notion of urban metabolism- “a series of interconnected heterogeneous and dynamic but contested and contestable processes of continuous quantitative and qualitative transformations that re-arranges humans and non-humans in new and often unexpected ways”.  相似文献