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Different Origins of the Fractionation of Platinum-Group Elements in Raobazhai and Bixiling Mafic-Ultramafic Rocks from the Dabie Orogen, Central China  [PDF]
Qing Liu,Quanlin Hou,Liewen Xie,Hui Li,Shanqin Ni,Yudong Wu
Journal of Geological Research , 2012, DOI: 10.1155/2012/631426
Abstract: Concentrations of the platinum group elements (PGEs), including Ir, Ru, Rh, Pt, and Pd, have been determined for both Raobazhai and Bixiling mafic-ultramafic rocks from the Dabie Orogen by fire assay method. Geochemical compositions suggest that the Raobazhai mafic-ultramafic rocks represent mantle residues after variable degrees of partial melting. They show consistent PGE patterns, in which the IPGEs (i.e., Ir and Ru) are strongly enriched over the PPGEs (i.e., Pt and Pd). Both REE and PGE data of the Raobazhai mafic-ultramafic rocks suggest that they have interacted with slab-derived melts during subduction and/or exhumation. The Bixiling ultramafic rocks were produced through fractional crystallization and cumulation from magmas, which led to the fractionated PGE patterns. During fractional crystallization, Pd is in nonsulfide phases, whereas both Ir and Ru must be compatible in some mantle phases. We suggest that the PGE budgets of the ultramafic rocks could be fractionated by interaction with slab-derived melts and fractional crystallization processes. 1. Introduction The platinum group elements (PGEs), including Os, Ir, Ru, Rh, Pt, and Pd, are strongly siderophile and chalcophile elements. They have similar geochemical behaviors during magmatic processes. Traditionally, the PGEs are subdivided into two groups, the compatible IPGEs (Os, Ir, and Ru) and the incompatible PPGEs (Rh, Pd, and Pt) [1]. It has been suggested that the IPGEs are refractory and tend to be retained in the mantle peridotites during partial melting [2]. In contrast, the PPGEs are concentrated in the base metal sulphides (e.g., pentlandite, chalcopyrite), which are released to the melts along with the molten sulfide melts [2]. Because of their unique geochemical characteristics, the PGEs can be used to identify the magma sources and unravel the complex petrogenetic processes, such as partial melting, melt percolation, and metasomatism in the mantle [1]. Mafic-ultramafic rocks have lower REE contents but higher PGE contents than other rocks, so the PGEs have advantages in studying their petrogenetic processes [1, 3–7]. In this study, we present the PGE data of both Raobazhai and Bixiling mafic-ultramafic rocks from Dabie Orogen, central China, to discuss their fractionation behaviours during magma evolution. The mechanisms of differentiation between these elements will be examined below, taking into account the geochemical affinities of the PGE and their partition in the mineral phases. The results also demonstrate that the PGEs can provide important information on the genesis
THE CHARACTERISTICS OF YIDUN-TYPE MAFIC-ULTRAMAFIC ROCKS AND THEIR COMPARISON WITH OPHIOLITES
义敦型镁铁—超镁铁岩的主要特征及其与蛇绿岩的对比

Zhang Qi,Li Dazhou,Zhang Kuiwu,Zhao Dasheng,
张旗
,李达周

岩石学报 , 1990,
Abstract: Yidun-type mafic-ultramafic rocks are a new type, which were raised by the authors at the time when we studied the mafic-ultramafic rocks in this region. It is similar to Alpine type but it is not ophiolite. The Yidun-type mafic-ultramafic body is mainly composed of metamorphic-peridotite (harzburgite and lherzolite are common, and dunite is limited), and is associated with a small amount of cumulative rocks(clinopyroxene peridotite, pyroxenite, amphibole-pyroxenite and etc.), gabbro and diabase. Its wall rock includes neritic limestone, sandy slate and rhyolite. The petrographic characteristics and chemical compositions of metamorphic peridotite are similar to that of the same kind of rock on the oceanic floor and indicate that both of them are members of upper mantle. Particularly, except LREE depleted ones(few samples), most REE distributions are the LREE-enriched. Its characteristics are not the same as that of the same kind of rocks in ophiolite, but it is similar to that of mantle inclusions in alkaline basalt. Gabbro is rich in Fe, Ti, P and large ion lithophile elements (LILE) as well as LREE, and poor in Mg and Al. It is different from the gabbro in ophiolite, but is similar to gabbros in Alpine area and in oceanic islands which suggests that the Yidun-type gabbro is a product of low-grade partial melting. The characteristics of Yidun-type body mentioned above are similar to Alpine type body, but tectonic environment of their emplacemcnt is different from those of ophiolite, therefore, it is very difficult to explain them by nappes. It may be believed that they are not ophiolite but are products derived from mantle and emplaced as diapir from below continental crust into shallow part of crust. The authors think that "Yi-dun-type" is of significance not only in theory, but also in ore-prospecting. We know that ophiolite is a rock assemblage with a particular structural implication, and represents residuals of oceanic crust and upper mantle; however Yidun-type body has no relations with evolution of oceanic basins, it is a member of mantle under continental crust. Although the features of metamorphic peridotite in Yidun-type body are similar to those in ophiolite, the ore-bearing features are different as they occur in different tectonic environments. Taking chromite as an example, due to relatively weak depleted degrees of Yidun-type body, important industrial deposites are rare, although chrome mineralization is commonly seen in the body. It is however favoutable for gold, asbestos, magnesite and precious stone deposites and so on.
Lg Coda Variations in North-Central Iran  [PDF]
Mojtaba Naghavi,Zaher Hossein Shomali,Mehdi Zare
International Journal of Geophysics , 2012, DOI: 10.1155/2012/673506
Abstract: Ground motion records in north-central Iran have been used in order to obtain the Lg coda , using stack spectral ratio method. The lateral variations in 0 and its frequency dependence are estimated in the 0.3–7.0 Hz frequency range which led to =267(±32)×0.71(±0.14). The observed variations in quality factor show low values of 0 in western part of the study region where bounded by relatively high values in southern and northern parts. Since the seismicity of the study area is quite shallow the obtained results can be attributed to the upper 30 km of the crust. The Damavand volcano and its surrounding region also exhibit variations in the value of 0 which result in low and intermediate values of 0 in western and eastern parts, respectively. Current seismicity in Damavand is mostly confined to its southwestern part, whereas our results proved to possess low values of 0. In general, most of factor variations can be attributed to the lateral heterogeneity as well as the severity of the crustal velocity gradient, and as expected the north-central Iran is well inferred as a tectonically active region.
PALEONTOLOGICAL STUDY OF THE ECHINODERMS IN THE QOM FORMATION (CENTRAL IRAN)
Earth Sciences Research Journal , 2007,
Abstract: the qom formation was formed in the oligo-miocene during the final sea transgression in central iran (figure 1). the best outcrop is located in the vicinities of the qom city, approximately 130 km at the south of tehran. in general, the great heights of the zone are the result of intense tectonic activities. these heights have a number of faults and folds. echinoderms are one of the most important and numerous fossil groups present in the qom formation and confirm the relationship of this environment with free waters. in the present investigation more than 100 prepared samples were studied and 17 species were identified, scanned and classified. these fossils are more abundant in the upper part of the a member, which illustrates the abundance and diversity in c1 and c3 sub-members belonging to the c member. to classify these samples, classical and up-to-date methods were used. however, the systematic schemes were used more frequently (moore, 1966; 1969-1971). besides these studies, the other concomitant microfossils in the formation were investigated simultaneously to estimate the accurate age of them. it is concluded that the study of oligo-miocene echinoderms present in the qom formation is essential and important because, at the same time, the central iran sea had a communicative role between the indo-pacific ocean and the mediterranean sea.
PALEONTOLOGICAL STUDY OF THE ECHINODERMS IN THE QOM FORMATION (CENTRAL IRAN)  [cached]
Khaksar Keyvan,Moghadam Iraj Maghfouri
Earth Sciences Research Journal , 2007,
Abstract: The Qom formation was formed in the Oligo-Miocene during the final sea transgression in Central Iran (Figure 1). The best outcrop is located in the vicinities of the Qom City, approximately 130 km at the south of Tehran. In general, the great heights of the zone are the result of intense tectonic activities. These heights have a number of faults and folds. Echinoderms are one of the most important and numerous fossil groups present in the Qom Formation and confirm the relationship of this environment with free waters. In the present investigation more than 100 prepared samples were studied and 17 species were identified, scanned and classified. These fossils are more abundant in the upper part of the A member, which illustrates the abundance and diversity in C1 and C3 sub-members belonging to the C member. To classify these samples, classical and up-to-date methods were used. However, the systematic schemes were used more frequently (Moore, 1966; 1969-1971). Besides these studies, the other concomitant microfossils in the formation were investigated simultaneously to estimate the accurate age of them. It is concluded that the study of Oligo-Miocene Echinoderms present in the Qom formation is essential and important because, at the same time, the Central Iran Sea had a communicative role between the Indo-Pacific Ocean and the Mediterranean Sea.
Lg Coda Variations in North-Central Iran  [PDF]
Mojtaba Naghavi,Zaher Hossein Shomali,Mehdi Zare
International Journal of Geophysics , 2012, DOI: 10.1155/2012/673506
Abstract: Ground motion records in north-central Iran have been used in order to obtain the Lg coda , using stack spectral ratio method. The lateral variations in and its frequency dependence are estimated in the 0.3–7.0?Hz frequency range which led to . The observed variations in quality factor show low values of in western part of the study region where bounded by relatively high values in southern and northern parts. Since the seismicity of the study area is quite shallow the obtained results can be attributed to the upper 30?km of the crust. The Damavand volcano and its surrounding region also exhibit variations in the value of which result in low and intermediate values of in western and eastern parts, respectively. Current seismicity in Damavand is mostly confined to its southwestern part, whereas our results proved to possess low values of . In general, most of factor variations can be attributed to the lateral heterogeneity as well as the severity of the crustal velocity gradient, and as expected the north-central Iran is well inferred as a tectonically active region. 1. Introduction The energy of a seismic wave decays while passing through a “real” medium such as the earth which is not completely elastic. The decay in energy due to nonelastic phenomena is called intrinsic attenuation and is characterized with the parameter, the large values of which represent small values of attenuation and as approaches zero the pertaining attenuation will become quite strong. Therefore, could be considered as a measure of elasticity of the media. In the present study, the factor is obtained for the Central Alborz in Iran using the Lg coda method. The Lg phase was originally observed using earthquakes occurred in California and has similar characteristics as SH phase with an average group velocity in the order of 3.5?km/s [1]. The regional Lg phase, comprised of multiple shear wave reverberations trapped in the crust, is often used to determine the quality factor variations for event-station distances less than 1500?km. The Lg phase is typically the most prominent short-period seismic phase observed over continental paths at distances greater than 200?km [2]. Lg phase can be treated as a sum of higher modes of surface waves, or multiple supercritically reflected waves trapped in the crust [2]. The average group velocity of Lg phase is in order of 3.3~3.6?km/s, while in stable shields show faster velocities than young active regions [3]. In this study, the Lg coda is estimated using ground motions recorded at 35 short-period seismic stations in north-central Iran, using
The Prevalence and Associated Factors of Central obesity in Northern Iran
G Veghari,M Sedaghat,H Joshaghani,A Hoseini
Iranian Cardiovascular Research Journal , 2010,
Abstract: Background: The main objective of this study was to evaluate theprevalence of central obesity and some related factors in the north of Iran(Golestan province) in 2006.Method: This was a population –based cross-sectional study that comprised2471 subjects (1250 males and 1221 female), using stratified cluster sampling.Interviewers recorded the data using the multidimensional questionnaire andanthropometric indexes. Waist circumference ≥102 and ≥88 cm categorized ascentral obesity for men and women respectively. SPSS 16.0 software was used forstatistical analysis.Results: The mean and standard deviation of age was 39.2±14.28 years andwaist circumference was 87.1±13.7 cm in men and 90.2±15.8 cm in women,respectively. In total, the prevalence of central obesity was 32.01% and it wassignificantly higher in women (57.2%) than in men (15.8%), in urban area (40.5%)than in rural areas (31.9%) and in uneducated people (52.3%) than in collegeeducated people (19.9) (P=0.001). Logistic regression analysis revealed thatcentral obesity was significantly associated with age, urbanization, parity andilliteracy (P<0.05).Conclusion: Central obesity was the most serious health problem in thenorth of Iran and it was more prevalent in women than men. Socio-demographicfactors such as younger age (between 15-25 and 25-35 years), urbanization,marital status and illiteracy were associated with central obesity. Furtherstudies are necessary to establish the association between central obesity andracial differences in this area.
Survey of Echinococcosis and Hydatidosis in Kashan Region, Central Iran
M Arbabi,H Hooshyar
Iranian Journal of Public Health , 2006,
Abstract: Hydatidosis is one of the major zoonotic diseases that cause considerable economic losses and public health problems worldwide. The present study was conducted to determine the prevalence of E. granulosus in domestic and wild carnivores and the infection rate of hydatid cyst in slaughtered animals and people in Kashan area, central Iran. A total of 142 carnivores including 70 stray dogs, 40 jackals, 22 red foxes, and 10 wolves were examined for the presence of E. granulosus, as well as, 170510 slaughtered sheep, 162665 goats and 13059 cattle for hydatid cyst infection. In addition, 500 inhabitants in rural areas were examined for antibodies to hydatid cyst. Results indicated that 43.7% of carnivores were infected with E. granulosus. Infection rate in slaughtered animals was 2.7%. Overall, the seroprevalence rate in human cases was 2.4%. Eighty-five patients including 47 females and 38 males were hospitalized. The mean annual incidence rate of hydatidosis in human was three cases per 100 000 populations. In general, the situation of the hydatidosis in the livestock and human and echinococcosis in the carnivores of the Kashan is similar to the other zones in Iran.
The Biggest Salt-Tongue Canopy of Central Iran  [PDF]
Mehran Arian, Hamideh Noroozpour
Open Journal of Geology (OJG) , 2015, DOI: 10.4236/ojg.2015.52005
Abstract: One of the most interesting salt structures is salt-tongue canopy. The Central Iran basin has a few salt provinces and in this paper, morphotectonic concept of the salt-tongue canopy on the west of Garmsar city has been investigated. In this study, field data coupling with the salt tectonic-related factors to provide a position for salt rocks in the west Garmsar. Firstly, various geological factors such as faults, folds and roads were extracted and compiled. This is because the factors mentioned above play important role in the instability of the region. The results of this study showed that the salt extrusion from the Lower Red formation is severe. Further, it is evident that the shortening of main structures has had a great impact on it whilst the salt movements have occurred within Garmsar Syncline. Finally, the paper concluded that the salt-tongue canopy in the region has increased the rates of salt extrusion.
Molecular Detection of Anaplasma bovis in Cattle from Central Part of Iran
Vahid Noaman,Parviz Shayan
Veterinary Research Forum , 2010,
Abstract: Anaplasma bovis is a leukocytotropic agent of bovine anaplasmosis and there is no available information about molecular study on this agent in cattle of Iran. In this study a total 150 cattle blood samples were collected from central part of Iran. The presence of A. bovis examined using light microscopic detection and species-specific nested polymerase chain reaction (nested-PCR) based on 16S rRNA gene. Of the 150 cattle, 4 (2.66 %) was positive for A. bovis by nested-PCR. These data is the first A. bovis DNA presence in cattle from central part of Iran.
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