Spatio-temporal occurrences and mineralogical–geochemical characteristics of airborne dusts in Khuzestan Province (southwestern Iran)     

A. Zarasvandi  E.J.M. Carranza  F. Moore  F. Rastmanesh 《Journal of Geochemical Exploration》2011,111(3):138-151

Dust storms in Khuzestan province (Iran) are causing problems in industries and human health. To mitigate the impact of those phenomena, it is vital to know the physical and chemical characteristics of airborne dusts. In this paper, we give an overview of the spatio-temporal occurrences and geochemical characteristics of airborne dusts in Khuzestan. Meteorological data from 10 stations in Khuzestan during 1996–2009 indicate (a) an average of 47 dust storm days per year, (b) a lowest annual average of 13 dust storm days in 1998, (c) a highest annual average of 104 dust storm days in 2008, and (d) an average increase of two dust storm days per year. Above-average number of dust storm days usually occurred in the cities of Dezful, Ahvaz, Masjed-e-Soleiman, Abadan and Bostan, whereas below-average number of dust storm days usually occurred in the cities of Mahshahr, Ramhormoz, Behbahan, Shoushtar and Izeh. XRD analyses of airborne dust samples collected in 2008 and 2009 show that the mineralogy of airborne dusts is dominated by calcite, followed by quartz and then kaolinite, with minor gypsum. SEM analyses of the samples indicate that airborne dusts have rounded irregular, prismatic and rhombic shapes. The sizes of airborne dusts vary from 2 to 52 μm, but 10 to 22 μm are the dominant sizes. The smallest and largest dust particles are clays, sulfates or carbonates. XRF and ICP analyses of the samples show that the most important oxide compositions of airborne dusts are SiO₂, Al₂O₃, Fe₂O₃, CaO and MgO. Estimates of enrichment factors (EF) for all studied elements show that Mn, Hf, U, Sc, K, V and Sr, with EF < 10, are of natural origin, whereas Na, Ni, Co, Ba and Cr, with EF > 10, are of anthropogenic origin. Flat REE patterns with depletion in Th, V, Nb, Zr and enrichment in Al, Rb, Sr and Mn indicate that airborne dusts in Khuzestan come from the same source, which is likely an eroded sedimentary environment outside Iran. In general, airborne dusts in Khuzestan are geochemically similar to airborne dusts elsewhere in the world.  相似文献   

Knowledge-guided data-driven evidential belief modeling of mineral prospectivity in Cabo de Gata,SE Spain     

E.J.M. Carranza  F.J.A. van RuitenbeekC. Hecker  M. van der MeijdeF.D. van der Meer 《International Journal of Applied Earth Observation and Geoinformation》2008

Spurious evidence and spurious spatial associations between target mineral deposits and certain classes of spatial data undermine GIS-based data-driven modeling of mineral prospectivity. In a case study application of data-driven evidential belief functions, such problems were recognized and then, based on sound geological judgment, were addressed accordingly. By invoking knowledge of genetic associations between mineral deposits of the type sought and spatial geological attributes (lithology, fault/fracture density, hydrothermal alteration intensity), spurious spatial associations depicted in ‘original’ evidence maps were addressed by treatment of input spatial data via applications of certain basic GIS functionalities in order to derive ‘treated’ evidence maps. By invoking knowledge of geological processes involved in the formation of mineral deposits of the type sought and knowledge of how operations to combine evidence maps function, the integration of evidence maps was guided such that the inter-play of geological processes involved in the formation of mineral deposits of the type sought is represented in the modeling procedure and such that spurious evidence is filtered and not transmitted into the output map representing likelihood of mineral deposit occurrence in every location within a study area. The results show that: (a) using ‘treated’ evidence maps, instead of ‘original’ evidence maps, results in better mineral prospectivity maps and, thus, (b) knowledge-guided data-driven modeling of mineral prospectivity is better than a ‘purely’ data-driven modeling of mineral prospectivity.  相似文献   

Book Review     

John Carranza 《Natural Resources Research》2017,26(1):113-115

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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   

Physical conditions in NGC 6164-5     

Agüero  E. L.  Carranza  G. J. 《Astrophysics and Space Science》1986,120(1):17-25

From spectroscopic observations of the emission lines H, 4959 and 5007[Oiii], H, 6584[Nii], 6717 and 6731[Sii] and some interferometric data in H and [Nii] it was established that NGC 6164 and NGC 6165 have characteristics of normal Hii regions for Ne and Te. They are embedded in a very tenuous medium nearly coincident with the Strömgren sphere of the central star HD 148937, corresponding to the outer peripheral structure described by Westerlund. Variations of the relative abundances of N, O, and S are discussed.  相似文献   

Application of Data-Driven Evidential Belief Functions to Prospectivity Mapping for Aquamarine-Bearing Pegmatites,Lundazi District,Zambia   总被引：6，自引：0，他引：6  

Carranza  E. J. M.  Woldai  T.  Chikambwe  E. M. 《Natural Resources Research》2005,14(1):47-63

A case application of data-driven estimation of evidential belief functions (EBFs) is demonstrated to prospectivity mapping in Lundazi district (eastern Zambia). Spatial data used to represent recognition criteria of prospectivity for aquamarine-bearing pegmatites include mapped granites, mapped faults/fractures, mapped shear zones, and radioelement concentration ratios derived from gridded airborne radiometric data. Data-driven estimates EBFs take into account not only (a) spatial association between an evidential map layer and target deposits but also (b) spatial relationships between classes of evidences in an evidential map layer. Data-driven estimates of EBFs can indicate which spatial data provide positive or negative evidence of prospectivity. Data-driven estimates of EBFs of only spatial data providing positive evidence of prospectivity were integrated according to Dempster’s rule of combination. Map of integrated degrees of belief was used to delineate zones of relative degress of prospectivity for aquamarine-bearing pegmatites. The predictive map has at least 85% prediction rate and at least 79% success rate of delineating training and validation deposits, respectively. The results illustrate usefulness of data-driven estimation of EBFs in GIS-based predictive mapping of mineral prospectivity. The results also show usefulness of EBFs in managing uncertainties associated with evidential maps.  相似文献   

Artificial Neural Networks for Mineral-Potential Mapping: A Case Study from Aravalli Province,Western India   总被引：1，自引：0，他引：1  

Porwal  Alok  Carranza  E. J. M.  Hale  M. 《Natural Resources Research》2003,12(3):155-171

This paper describes a GIS-based application of a radial basis functional link net (RBFLN) to map the potential of SEDEX-type base metal deposits in a study area in the Aravalli metallogenic province (western India). Available public domain geodata of the study area were processed to generate evidential maps, which subsequently were encoded and combined to derive a set of input feature vectors. A subset of feature vectors with known targets (i.e., either known mineralized or known barren locations) was extracted and divided into (a) a training data set and (b) a validation data set. A series of RBFLNs were trained to determine the network architecture and estimate parameters that mapped the maximum number of validation vectors correctly to their respective targets. The trained RBFLN that gave the best performance for the validation data set was used for processing all feature vectors. The output for each feature vector is a predictive value between 1 and 0, indicating the extent to which a feature vector belongs to either the mineralized or the barren class. These values were mapped to generate a predictive classification map, which was reclassified into a favorability map showing zones with high, moderate and low favorability for SEDEX-type base metal deposits in the study area. The method demarcates successfully high favorability zones, which occupy 6% of the study area and contain 94% of the known base metal deposits.  相似文献   

A Hybrid Neuro-Fuzzy Model for Mineral Potential Mapping   总被引：5，自引：0，他引：5  

Alok Porwal  E. J. M. Carranza  M. Hale 《Mathematical Geology》2004,36(7):803-826

A GIS-based hybrid neuro-fuzzy approach to mineral potential mapping implements a Takagi–Sugeno type fuzzy inference system in a four-layered feed-forward adaptive neural network. In this approach, each unique combination of predictor patterns is considered a feature vector whose components are derived by knowledge-based ordinal encoding of the constituent predictor patterns. A subset of feature vectors with a known output target vector (i.e., unique conditions known to be associated with either a mineralized or a barren location), extracted from a set of all feature vectors, is used for the training of an adaptive neuro-fuzzy inference system. Training involves iterative adjustment of parameters of the adaptive neuro-fuzzy inference system using a hybrid learning procedure for mapping each training vector to its output target vector with minimum sum of squared error. The trained adaptive neuro-fuzzy inference system is used to process all feature vectors. The output for each feature vector is a value that indicates the extent to which a feature vector belongs to the mineralized class or the barren class. These values are used to generate a favorability map. The procedure is applied to regional-scale base metal potential mapping in a study area located in the Aravalli metallogenic province (western India). The adaptive neuro-fuzzy inference system demarcates high favorability zones occupying 9.75% of the study area and identifies 96% of the known base metal deposits. This result is significant both in terms of reduction in search area and the percentage of deposits identified.  相似文献