The Grader layered intrusion (Havre-Saint-Pierre Anorthosite, Quebec) and genesis of nelsonite and other Fe–Ti–P ores     

Bernard Charlier  Emmanuel Sakoma  Martin Sauv  Kerry Stanaway  Jacqueline Vander Auwera  Jean-Clair Duchesne 《Lithos》2008,101(3-4):359-378

The Grader layered intrusion is part of the Havre-Saint-Pierre anorthosite in the Grenville Province (Quebec, Canada). This intrusion has a basin-like morphology and contains significant resources of Fe–Ti–P in ilmenite and apatite. Outcropping lithologies are massive oxide alternating with anorthosite layers, banded ilmenite–apatite–plagioclase rocks and layered oxide apatite (gabbro-)norites. Drill cores provide evidence for stratigraphic variations of mineral and whole rock compositions controlled by fractional crystallization with the successive appearance of liquidus phases: plagioclase and ilmenite followed by apatite, then orthopyroxene together with magnetite, and finally clinopyroxene. This atypical sequence of crystallization resulted in the formation of plagioclase–ilmenite–apatite cumulates or “nelsonites” in plagioclase-free layers. Fine-grained ferrodiorites that cross-cut the cumulates are shown to be in equilibrium with the noritic rocks. The high TiO₂ and P₂O₅ contents of these assumed liquids explains the early saturation of ilmenite and apatite before Fe–Mg silicates, thus the nelsonites represent cumulates rather than crystallized Fe–Ti–P-rich immiscible melts. The location of the most evolved mineral and whole rock compositions several tens of meters below the top of the intrusion, forming a sandwich horizon, is consistent with crystallization both from the base and top of the intrusion. The concentrations of V and Cr in ilmenite display a single fractionation path for the different cumulus assemblages and define the cotectic proportion of ilmenite to 21 wt.%. This corresponds to bulk cotectic cumulates with ca. 8 wt.% TiO₂, which is significantly lower than what is commonly observed in the explored portion of the Grader intrusion. The proposed mechanism of ilmenite-enrichment is the lateral removal of plagioclase due to its relative buoyancy in the dense ferrodiorite melt. This plagioclase has probably accumulated in other portions of the intrusion or has not been distinguished from the host anorthosite.  相似文献   

Geochemical Mineral Exploration: Should We Use Enrichment Factors or Log-Ratios?     

Emmanuel John M. Carranza 《Natural Resources Research》2017,26(4):411-428

According to previous studies, the use of enrichment factors in environmental studies is inconsistent with its original concept and that such indiscriminate use of enrichment factors should be stopped. In this contribution, it is shown through spatial correlation analysis that using enrichment factors is no better than using log-ratios of geochemical data for mapping of deposit-related anomalies.  相似文献   

Natural Resources Research Publications on Geochemical Anomaly and Mineral Potential Mapping,and Introduction to the Special Issue of Papers in These Fields     

Emmanuel John M. Carranza 《Natural Resources Research》2017,26(4):379-410

In its 26 years of existence, the journal of Natural Resources Research (NRR) has published and continues to publish papers on geochemical anomaly and mineral potential mapping. This is consistent with its aims and scope to publish quantitative studies of natural (mainly but not limited to mineral) resources exploration, evaluation and exploitation, including environmental and risk-related aspects. Over the years, NRR has contributed significantly more to the publication of developments in mineral potential mapping and notably less to the publication of developments in geochemical anomaly mapping. In more detail, NRR has contributed significantly more to the publication of research on development of robust quantitative methods for analysis and synthesis of spatial evidence of mineral potential but notably less to the publication of research on development of geologically focused models of mineral potential. The editorship of NRR recognizes the latter as a challenge to promote further research on development of numerically robust as well as geologically focused mineral potential models, and this special issue is a major initiative in response to that challenge. The recent inclusion of Natural Resources Research for coverage by the Clarivate Analytics (formerly the Institute for Scientific Information) in the Science Citation Index Expanded? and Journal Citation Reports^® (JCR) Science Edition will help make Natural Resources Research meet that challenge.  相似文献   

Petrogenesis,zircon U–Pb age,and geochemistry of the A-type Mogou syenite,western Henan Province: Implications for Mesozoic tectono-magmatic evolution of the Qinling Orogen     

Xinyu He  Jionghui Wang  Changming Wang  Emmanuel John M Carranza  Liang Chen  Bin Wu 《Journal of Earth System Science》2016,125(3):585-603

The Mogou syenite intruded into the Mesoproterozoic Xiong’er Group is the main lithostratigraphic unit, along the southern margin of the North China Craton (NCC). This paper reports zircon LA-ICP-MS data, whole-rock major and trace element compositions of late Triassic magmatic rocks in the Mogou syenite, in order to constrain the formation age of the Mogou syenite, research the origin and evolution of the magma and analyse the geodynamic setting of the Qinling Orogen (QO) in Late Triassic. These rocks consist of medium- to coarse-grained syenite and fine-grained quartz syenite. Zircon U–Pb dating yields a crystallization age of 226.5±2.7 Ma. The syenites are characterized by high SiO₂ (63.49–72.17%), alkali (K₂O+Na₂O of 11.18–15.38%) and potassium (K₂O/Na₂O of 2.88–28.11), are peralkaline or metaluminous (molar A/CNK of 0.87–1.02) and belong to shoshonite series. The syenites have ΣREE of 33.01–191.30 ppm, LREE/HREE of 14–20, (La/Yb)_N of 11–24, with LREE-rich distribution pattern and obvious differentiation between HREE and LREE. Eu anomalies are positive for the medium- to coarse-grained syenite and weakly negative for the fine-grained quartz syenite. In addition, the syenites are enriched in large-ion lithophile elements (Ba, K, Sr, and Pb) but depleted in high strength field elements (Ti, Ta, Nb, Zr, and Hf), and have high differentiation indices of 91.69–97.06. These geochemical features indicate that the primary magma of the Mogou syenite most likely originated from a mantle source with minor crustal component, and underwent a fractional crystallization process during its emplacement. The late Triassic A-type Moguo syenite along the southern margin of the NCC was generated in the late stage of the syn-collision event of QO, recording a transition period from compression to extension at around 227 Ma.  相似文献   

Structural characterization of the Misajé granitic pluton (NW Cameroon): constraints from magnetic and field observations     

Eric Martial Fozing  Théophile Njanko  Séta Naba  Maurice Kwékam  Emmanuel Njonfang  Pierre Rochette 《International Journal of Earth Sciences》2016,105(8):2285-2309

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Dispersive Fluxes Within and Over a Real Urban Canopy: A Large-Eddy Simulation Study     

Akinlabi  Emmanuel  Maronga  Björn  Giometto  Marco G.  Li  Dan 《Boundary-Layer Meteorology》2022,185(1):93-128

Boundary-Layer Meteorology - Large-eddy simulations (LES) are conducted to study the transport of momentum and passive scalar within and over a real urban canopy in the City of Boston, USA. This...  相似文献   

Fluid-induced high-temperature metasomatism at Rundv?gshetta in the Lützow-Holm Complex,East Antarctica: Implications for the role of brine during granulite formation     

Kazuki Takahashi  Toshiaki Tsunogae  Emmanuel Nwachukwu Ugwuonah 《地学前缘(英文版)》2018,9(5):1309-1323

We report new petrological, phase equilibria modeling, and fluid inclusion data for pelitic and mafic granulites from Rundv?gshetta in the highest-grade region of the Neoproterozoic Lützow-Holm Complex(LHC),East Antarctica, and provide unequivocal evidence for fluid-rock interaction and high-temperature metasomatism in the presence of brine fluid. The studied locality is composed dominantly of well-foliated pelitic granulite(K-feldspar+quartz+sillimanite+garnet+ilmenite) with foliation-parallel bands and/or layers of mafic granulite(plagioclase+orthopyroxene+garnet+ilmenite+quartz+biotite). The boundary between the two lithologies is defined by thin(about 1 -20 cm in thick) garnet-rich layers with a common mineral assemblage of garnet+plagioclase+quartz+ilmenite+biotite ? orthopyroxene. Systematic increase of grossular and decrease of pyrope contents in garnet as well as decreasing Mg/(Fe+Mg) ratio of biotite from the pelitic granulite to garnet-rich rock and mafic granulite suggest that the garnet-rich layer was formed by metasomatic interaction between the two granulite lithologies. Phase equilibria modeling in the system NCKFMASHTO demonstrates that the metasomatism took place at 850 -860℃, which is slightly lower than the peak metamorphism of this region, and the modal abundance of garnet is the highest along the metapeliteemetabasite boundary(up to 40%), which is consistent with the field and thin section observations. The occurrence of brine(7.0 -10.9 wt.% Na Cleqfor ice melting or 25.1 -25.5 wt.% NaC leqfor hydrohalite melting) fluid inclusions as a primary phase trapped within plagioclase in the garnet-rich layer and the occurrence of Cl-rich biotite(Cl = 0.22 -0.60 wt.%) in the metasomatic rock compared to that in pelitic(0.15 -0.24 wt.%) and mafic(0.06-0.13 wt.%) granulites suggest infiltration of brine fluid could have given rise to the high-temperature metasomatism. The fluid might have been derived from external sources possibly related to the formation of major suture zones formed during the Gondwana amalgamation.  相似文献   

Empirical Estimation of Uniaxial Compressive Strength of Rock: Database of Simple,Multiple, and Artificial Intelligence-Based Regressions     

Aladejare  Adeyemi Emman  Alofe  Emmanuel Damola  Onifade  Moshood  Lawal  Abiodun Ismail  Ozoji  Toochukwu Malachi  Zhang  Zong-Xian 《Geotechnical and Geological Engineering》2021,39(6):4427-4455

Geotechnical and Geological Engineering - Empirical relationships for estimating Uniaxial Compressive Strength (UCS) of rock from other rock properties are numerous in literature. This is because...  相似文献   

Development of a User-Centred Web-Mapping Application for Ocean Modellers     

Marta Padilla-Ruiz  Emmanuel Stefanakis  Ian Church 《Marine Geodesy》2013,36(6):507-534

Abstract

This paper reports on the User-Centred Design and development of a web-mapping application from the Ocean Mapping Group (OMG) at the University of New Brunswick (UNB), to deliver ocean mapping data to ocean modellers. First, a work domain analysis was conducted to determine the required application functionality and content, consisting of an ocean modeller informal interview, a competitive analysis, and an online survey. Taking insight from the work domain analysis, a requirements document was prepared to support the development of the first application prototype. This prototype was then evaluated by eight target users, using a cognitive walkthrough and an online survey. The results from this evaluation led to a series of revisions to the functionality, content, and interface of the web-mapping application, establishing the revised prototype. The results showed a useful tool, end-user satisfaction, and stated a wide range of recommendations to enhance functionality for the next steps of the development.  相似文献   

Physical studies of Centaurs and Trans-Neptunian Objects with the Atacama Large Millimeter Array     

Arielle Moullet  Emmanuel Lellouch  Mark Gurwell 《Icarus》2011,213(1):382-392

Once completed, the Atacama Large Millimeter Array (ALMA) will be the most powerful (sub)millimeter interferometer in terms of sensitivity, spatial resolution and imaging. This paper presents the capabilities of ALMA applied to the observation of Centaurs and Trans-Neptunian Objects, and their possible output in terms of physical properties. Realistic simulations were performed to explore the performances of the different frequency bands and array configurations, and several projects are detailed along with their feasibility, their limitations and their possible targets. Determination of diameters and albedos via the radiometric method appears to be possible on ∼500 objects, while sampling of the thermal lightcurve to derive the bodies’ ellipticity could be performed at least 30 bodies that display a significant optical lightcurve. On a limited number of objects, the spatial resolution allows for direct measurement of the size or even surface mapping with a resolution down to 13 milliarcsec. Finally, ALMA could separate members of multiple systems with a separation power comparable to that of the HST. The overall performance of ALMA will make it an invaluable instrument to explore the outer Solar System, complementary to space-based telescopes and spacecrafts.  相似文献