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1.
Monomineral universal clinopyroxene and garnet barometers for peridotitic,eclogitic and basaltic systems 总被引：1，自引：1，他引：0
I.V. Ashchepkov T. Ntaflos A.M. Logvinova Z.V. Spetsius H. Downes N.V. Vladykin 《地学前缘(英文版)》2017,8(4):775-795
New versions of the universal Jd-Di exchange clinopyroxene barometer for peridotites,pyroxenites and eclogites,and also garnet barometer for eclogites and peridotites were developed.They were checked using large experimental data sets for eciogitic(~530) and peridotitic systems(650).The precision of the universal Cpx barometer for peridotites based on Jd-Di exchange is close to Cr-Tschermalite method produced by Nimis and Taylor(2000).Cpx barometer was transformed by the substitution of major multiplier for K_D by the equations dependent from Al-Na-Fe.Obtained equation in combination with the thermometer of Nimis and Taylor(2000) allow to reconstruct position of the magma feeder systems of the alkali basaltic magma within the mantle diapirs in modern platforms like in Vitim plateau and other Southern Siberia localities and several localities worldwide showing good agreement of pressure ranges for black and green suites.These equations allow construct PTX diagrams for the kimberlite localities in Siberia and worldwide calculating simultaneously the PT parameters for different groups of mantle rocks.They give very good results for the concentrates from kimberlite lamproites and placers with mantle minerals.They are useful for PT estimates for diamond inclusions.The positions of eclogite groups in mantle sections are similar to those determined with new Gar—Cpx barometer produced by C.Beyer et al.(2015).The Fe rich eclogites commonly trace the boundary between the lower upper parts of subcontinental lithospheric mantle(SCLM) at 3-4 CPa marking pyroxenite eclogites layer.Ca-rich eclogites and especially grospydires in SCLM beneath Precambrian kimberlites occurs near pyroxenite layer but in younger mantle sections they became common in the lower parts.The diamondiferous Mg Cr-less group eclogites referring to the ancient island arc complexes are also common in the middle part of mantle sections and near 5-6 GPa.Commonly eclogites in lower apart of mantle sections are remelted and trace the high temperature convective branch.The Mg-and Fe-rich pyroxenites also show the extending in pressure trends which suggest the anatexic melting under the influence of volatiles or under the interaction with plums. 相似文献
2.
Idu–Karmo of the federal capital territory, Abuja, is located within the weathered basement aquifers of Northern Nigeria. Fifteen groundwater samples obtained were analysed for their major ionic components. The physical properties show that the water is slightly acidic to neutral (6.0–7.0) and has moderate to very high values of electrical conductivity (155–2230 µS/cm).The dominant hydrochemical facies of groundwater is the Ca–Cl2 groundwater type. Irrigation parameters measured include: SAR which ranges from 0.12 to 1.06; TH which ranges from 0.8 to 196; KR ranges from 0.03 to 0.42; PI which ranges from 46 to 199; and RSC ranges from ??131.90 to 3.43. These parameters (SAR, total hardness, Kelly’s ratio, permeability index and residual sodium carbonate) show that the water is suitable for agricultural purpose except for the magnesium ratio which has a high unsuitability for irrigation, probably due to the presence of ferro-magnesian minerals contained in the calc-alkaline basement rocks of the Idu–Karmo area. The results of the geochemical survey reveal major ionic components are in the order Cl??>?HCO3??>?NO3??>?SO42? and Mg2+?>?Ca2+?>?Na+?>?K+. Comparison with WHO and APHA standards shows that all the ionic concentrations satisfy all permissible limits for drinking purpose except for elevated concentrations of nitrate which probably may have arisen from poor handling of domestic wastes, leakages from nearby septic tanks/soak-away and the excessive use of fertilisers. Qualitatively, treatment is required especially on the nitrate-contaminated areas to make the water fit for drinking and irrigation. 相似文献
3.
Equivalent in principle to type localities and type specimens in biology and paleontology, geological type sections and type localities, whether for sedimentary, metamorphic or igneous units, are critically important sites as long-term reference and research localities and for geo-education of students. Unlike type specimens that are housed in museums or established institutions of learning, most geological type sections and localities are in field settings and, if they are not located in National Parks or other reserves with some legislated protection, run the risk of being destroyed, inundated, buried by earthworks or otherwise modified. The history of the geological sciences in Australia is such that a number of type localities, or stratigraphic type sections, have been destroyed by local government actions, or developers through lack of knowledge of their importance, or lack of knowledge of their existence. Examples of the severe modification or loss of type sections include those of the Maxicar beds, the Tims Thicket Limestone and the Eaton Sand. The UK, a leader in the field of Geoconservation and with a number of global stratotype section and point locations as well as many other type sections identified within its borders, provides models for preserving and managing important geological sites and type sections. Whole-of-government and local governments are involved in the registering and protection of important geological sites. Aspects of the UK model may be adapted to help secure geological type sections and localities in Australia. While some type sections and heritage localities are already protected, to improve the level of protection for more sites we propose a long-term, multi-pronged approach: creation of an inventory of all nominated locations; registration of appropriate sites at Local, State or Federal government levels, where current legislation allows; education of landowners and land managers, both government and non-government to highlight the importance of type sections to science; and securing more geological type sections and localities in some form of reserve. 相似文献
4.
5.
Preliminary Statistics of Temperatures and Pressures for Formation of Eclogites, Granulites and Peridotites in China 总被引：1，自引：0，他引：1
HuBaoqun WangFangzheng SunZhanxue LiuChengdong BaiLihong 《中国地质大学学报(英文版)》2004,15(2):183-192
The rock-forming temperatures and pressures represent the p-T points of the local regions in the lithosphere at a certain age, providing some important information on rock formation. Based on the preliminary statistics on the temperatures and pressures for the formation of eclogites, granulites and peridotites in China, the variant ranges are given, in this paper, of temperatures, pressures and linear geothermal gradients of eclogites, granulites and peridotites. In addition, since the eclogite is different from granulite and peridotite in the p-T diagram, these three rocks can be classified into two groups: the first group includes eclogites and the second group granulites and peridotites. Then, the p-T correlation functions of these two groups of rocks are provided. Finally, the two groups of rocks have different geothermal gradients at the same pressure gradient or have different pressure gradients at the same geothermul gradient. The temperatures and pressures for the formation of the rocks can be calculated from the mineral chemical compositions, but the depths (H) for the rock formation can be calculated only under the hypotheses of given p-H (or T-H) correlation functions. The explanations for the ultrahigh pressure metamorphism vary obviously with different hypotheses. 相似文献
6.
Ion-microprobe analysis of zircons from an andalusite-bearing orthogneiss within the major Alpujárride nappe complex in the central part of the Betic Cordilleras has yielded a Hercynian age of 285?±?5 (2σ) Ma for euhedral rims, interpreted as the magmatic age of the andalusite-bearing biotite granite parent rock for the gneisses. Zircon age zoning systematics suggest a Paleozoic sedimentation age for the parent material for the anatectic source rock. Zircon cores represent several groups of ages: (1) Archean, c. 2.7?Ga; (2) Early Proterozoic, 2.2–2.0?Ga; (3) Middle Proterozoic, 1.1–0.9?Ga; (4) Pan-African, 0.8–0.5?Ga; including a well-defined event at 612?±?13 (2σ) Ma. Paragenetic and textural relations indicate that gneissification took place during a high-P (12–13?kbar) low-T (450–500?°C) collisional event during which the primary Alpine nappe pile was produced. The second and final Alpine tectono-metamorphic event led to reorganization of the primary nappe pile by extensional tetonics with coeval very fast rock uplift and cooling (from c. 8? to c. 1?kbar and c. 600 to 100?°C within the period 19.5–18.5?Ma). The fast uplift/cooling stage was triggered by slab break-off which is thought to have induced diapiric underplating by high-T asthenospheric material. This may have heated the collisional wedge, causing thermal weakening which might have advanced the late stage fast uplift/cooling. The Alpine events did not leave a zircon crystallization record. The inherited, Archean–Pan-African zircon age pattern corresponds to that established for the Hercynian basement in central and southern Europe which is considered as reworked Gondwana crust. Deeper levels of core complexes within the Betic-Rif belt thus belong to the pre-Triassic basement of the Tethyan realm (Betic-Ligurian lithosphere) and represent reworked material ultimately derived from Archean and Proterozoic rock complexes from the Gondwana crustal domain. This study implies that thermobarometry of rock complexes which went through several phases of tectono-metamorphic reworking may render ambiguous results if based upon field observations and petrography alone. Zircon ion-microprobe dating may provide additional constraints required to arrive at a feasible tectono-metamorphic history, that is P-T-t trajectory, for such rock complexes. 相似文献
7.
In the growing field of Geoheritage, Geoconservation, Geo-education and Geotourism, there is a need to manage sites of geoheritage significance. While there is some great geology in nature available to appreciate for scenic value, education, tourism and research, many locations need to be protected from people and commercialism (e.g. the Iridium layer at the K/T boundary in Gubbio, Italy, the Ediacaran fauna in South Australia, the Burgess Shale in Canada or the zircon crystals at Jack Hills, among many others), and some locations need hazard management to protect people (e.g. continuously collapsing cliffs that have potential to be hazardous via rock falls, or slippery slopes, or high cliffs that are treacherous, or ‘king waves’ on rocky shores). The concept of the ‘8Gs’ is intended as a policy-style guidance that logically and progressively links Geology and Geoheritage through a series of steps to Geo-education and Geotourism. There is a logical progression from Geology the Science, through to Geoheritage and the identification of sites of geoheritage significance, to the establishment of Geosites/Geoparks, Geoconservation, leading to Geomanagement, Geo-education and Geotourism. Geomanagement needs to be undertaken prior to the use of sites for Geo-education and Geotourism. In relation to Geomanagement, sites need to be investigated for safety issues, and for the protection of their geological features. Geodiversity, the eighth ‘G’, is outside the progression but plays an important part in underpinning biodiversity. There is also a need to address and manage geodiversity in a given region or specific site to help understand and manage biodiversity. 相似文献
8.
Liu Qingsheng Department of Geophysics China University of Geosciences Wuhan The State Key Laboratory of Oil/Gas Reservoir Geology Exploitation of China Institute of Chengdu Technology Chengdu Wu Qifan Li Haixia Department o 《中国地质大学学报(英文版)》2001,12(2)
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9.
O. Bruguier D. Bosch R. T. Pidgeon D. I. Byrne L. B. Harris 《Contributions to Mineralogy and Petrology》1999,136(3):258-272
Conventional and SHRIMP U-Pb analyses of zircon, monazite, titanite and apatite from the high grade rocks of the Northampton
Complex in Western Australia provide constraints on the timing of metamorphic processes and deformation events in the northern
Darling Mobile Belt (western margin of the Archean Yilgarn Craton). Paragneisses and mafic volcanics and/or intrusions have
undergone granulite facies metamorphism in a probable extensional tectonic setting prior to formation of W- to NW-verging
folds and thrusts cut by normal shears (interpreted as late collapse structures) during the main deformation event (D1). These structures are folded by open to tight folds with NW-striking axial surfaces developed in a second, NE-SW contractional
event (D2). Zircons from a mafic granulite provide an age of 1079 ± 3 Ma attributed to new zircon growth prior to, or at the peak of
regional granulite facies metamorphism. Metamorphic monazites extracted from a paragneiss yield an identical age of 1083 ± 3 Ma.
The similarity of ages between zircons from the mafic granulite (1079 ± 3 Ma) and monazites from the paragneiss (1083 ± 3 Ma)
is interpreted to reflect fast cooling and/or rapid uplift, which is consistent with thrusting of the gneissic units during
the first deformation event (D1) associated with the onset of retrograde metamorphism. Granitic activity at 1068 ± 13 Ma was followed by intrusion of post-D2 pegmatite (989 ± 2 Ma), which constrains the end of metamorphism and associated deformation. Cooling of the complex to about
500 °C is timed by the apatite age of 921 ± 23 Ma. SHRIMP U-Pb ages of detrital zircons from a paragneiss sample yield a maximum
age of 2043 Ma, with no evidence of an Archean Yilgarn signature. A majority of ages between 1.6 and 1.9 Ga are consistent
with derivation from the Capricorn Orogen on the northern margin of the Yilgarn Craton. Younger detrital zircons with 1150–1450 Ma
ages, however, indicate an additional source that had undergone early Grenvillian igneous or metamorphic event(s) and also
places a maximum age constraint upon deposition. The source of this clastic material may have been from within the southern
Darling Mobile Belt or from Greater India (adjacent to the Northampton Complex in Rodinia reconstructions). This study documents
an extended Grenvillian history, with basin formation, sedimentation, granulite facies metamorphism, contractional tectonics
(two periods with orthogonal directions of shortening) and late pegmatite emplacement taking place between 1150–989 Ma on
the western margin of the Yilgarn Craton. Ages recorded in this study indicate that the proposed global distribution of Grenvillian
belts during assembly of the Rodinia supercontinent should be reassessed to include the Darling Mobile Belt.
Received: 7 January 1998 / Accepted: 10 March 1999 相似文献
10.
11.
E. K. Esawi 《Environmental Geology》2009,57(1):111-117
TerCharts is a comprehensive, fast, flexible, and versatile ternary charting utility that can be used for ternary data presentation
analysis and modeling across many scientific disciplines. TerCharts is developed using Microsoft (MS) Excel 2003 and Visual
Basic for Applications (VBA) which is an object oriented programming language developed by MS as a tool to enhance the capabilities
of MS products. The Excel–VBA interface is important because normally chemical, geochemical, and mineralogical data used in
teaching and basic research are processed using Excel spreadsheets, making TerCharts a more convenient tool for generating
ternary charts which in turn can be used for data presentation and analysis. Ternary charts generated by this utility can
be improved, edited, and modified utilizing MS Excel’s powerful charting and editing techniques. 相似文献
12.
正Cerberus Fossae(CF)is a large fracture system on Mars that extends for more than 1200 km.The structures,or fossae,are southeast of,and oriented approximately radially to,the large shield volcano Elysium Mons.An 相似文献
13.
M. K. Ansari M. Ahmad Rajesh Singh T. N. Singh 《Journal of the Geological Society of India》2018,91(1):47-56
The Saptashrungi gad temple (SGT) situated on basaltic hills belongs to Deccan volcanic of Upper Cretaceous to Lower Eocene, is one among the 51 Shakti Peeths and most holy place for pilgrims. Rockfall is a major problem in the past and causing danger to the lives of the villagers settled at the toe of the SGT hill as well as the pilgrims who perform parikrama along the tracks. On the evening of 16 April 2011, an old woman died due to rockfall at SGT hill when she was performing parikrama, moreover, two persons got injured during the deliverance process of this old woman from the continuous rockfall activity. The problem of rockfall could be linked to rainfall, jointing, weathering, man-made or the compounding of all. In this research, the rockfall hazard analysis at SGT hill is assessed using both 2D and 3D rockfall programs along the two parikrama paths: Parikrama Path 1 (or the Badi Parikrama Path ‘BPP’), and Parikrama Path 2 (or the Chhoti Parikrama Path ‘CPP’). Also, the study area of the SGT hill has been divided into eight zones (Zone#01 to Zone#08), based on field observations, orientations of joint sets and hill slope faces and eighteen topographic profiles (AA' to RR') have been taken from these eight zones for rockfall analysis. A detailed topographic survey along with field investigation has been carried out along the temple for ascertaining the nature of rock, discontinuity orientations, and slope geometry. DEM has been generated using topographic profile in ArcGIS to facilitate the 3D rockfall analysis. Maximum rock block sizes are taken into the analysis and run-out distance, bounce height, kinetic energy and velocity of the basaltic blocks are evaluated separately. Based on the analyzed data, the rockfall hazard zone map has been prepared and site having potential rockfall risks have been identified. Finally, wire/net meshing has been proposed after removal of unstable blocks as a stabilization and protection measures.It is worth mentioning here that for the first time rockfall hazard assessment was made in such detail for a site. Suggestions made are implemented by the State Government for the protection of the temple as well as the life of pilgrims performing the parikrama from the rockfall. 相似文献
14.
This paper briefly introduces twenty-one versions of garnet-biotite Fe-Mg exchange geothermometry,points out the sources of systematic errors inherent in geothermometry.The sources lie in that:(1) ideal Fe-Mg mixing in garnet and biotite is assumed;(2)non-ideal properties of bot garnet and biotite are not considered completely;(3) minor elements-Mn, Ca in garnet,and Al^Ⅵ,Ti,Mn in biotite are almost neglected;(4)effects of pressure on equilibrium,although little,are almost not taken into consideration,and experiments were conducted at one fixed pressure;(5)the data used for egression analysis is too scarce in quantity;(6)internal consistency of the data used for empirical calibration is not fully guaranteed;(7) the authors take energy parameters W‘s(Margule‘s parametrs)independent of pressure and temperature,though the former are actually the functions of the latter items;and (8)the most important composition-activity relationship is not consistent with the mineral compositions used for calibration.Furthermore,it is believed that empirical calibrations cannot avoid the following problems;(1) effect of retrograde metamorphism;(2)inconsistent data set;(3)effect of pressure on temperature estimation;and (4)effect of Fe^3 calculation.Exact experimental work should be done in order to accurately calibrate the geotermometer in which the Margule‘s parameters should be treated as the functions of pressure,temperature,and mineral compositions. 相似文献
15.
Age and Metal Source Constraints for Gold Deposits in Southeast Guizhou Province, China, from Re-Os and He-Ar Isotopes in Arsenopyrites 总被引：1，自引：0，他引：1
Please refer to the attachment(s) for more details 相似文献
16.
《Geochimica et cosmochimica acta》1987,51(9):2349-2354
Pressure-temperature-composition (P, T, x) relations for the co-existing vapor and liquid phases in the system NaCl-H2O were determined experimentally at 450, 475, and 500°C. Data for each isotherm include P-x relations near the critical point and extend to the three-phase assemblage vapor-liquid-halite on the vapor side. On the liquid side the P-x data range from the critical point to the room-temperature halite saturation point (~25 wt.% NaCl). Critical pressures were calculated from measured pressures and compositions and classical theory. The results generally support the few data points of Urusova (1974, 1975) and Ölander and Liander (1950) but differ markedly from the extensive data of Sourirajan and Kennedy (1962). 相似文献
17.
The Sinai Peninsula constitutes an important district of the Egyptian lands where it forms a triangular portion in northeastern Egypt. The southern Sinai metamorphic complexes are the northern uppermost part of the Arabian–Nubian Shield revealing the upper and middle crust from the East African Orogeny, in which they tectonically evolved. The Feiran–Solaf metamorphic complex (FSMC) of Sinai, Egypt is one of the highest grades metamorphic complexes of a series of basement domes that trends NW and crops out throughout the Arabian–Nubian Shield. The main aim of the present study is to apply the geospatial technology and to represent the capability of the geospatial technology to estimate the combined influence of lithology and structure studies, and to construct the lithological and structural maps of FSMC. Furthermore, detailed structural analysis is carried out to reveal the different ductile and brittle deformational events and proposed the tectonic evolutionary model for the study area. Mainly geospatial technology and structural analysis software have been used to go well with the aim of the present study. Developing specific image processing of satellite images and structural analysis were succeeded to discriminate the various lithological rock units, and the geological structural features of the FSMC, using geographic information system tools to construct the different thematic maps, were extracted. The present detailed investigations of the enhanced satellite images, structural analysis, and field verification reveal that the FSMC reached its present tectonic setting through more than four deformational phases concluding that the Pan-African Najd Fault System continued in Sinai and was reactivated during Red Sea tectonics as indicated by the dextral shear zone (Rihba) bordering the northern side of the FSMC. 相似文献
18.
WANG Zhongliang YANG Liqiang GUO Linnan LIU Yue ZHANG Chao LI Ruihong ZHANG Liang ZHENG Xiaoli ZHAO Rongxin 《地质学报》2014,88(Z2):1167-1168
Please refer to the attachment(s) for more details. 相似文献
19.
《Applied Geochemistry》1987,2(2):217-226
Well characterized synthetic δ-MnO2 can be used successfully for trace metal speciation studies in natural waters. Characteristics and adsorption behavior of δ-MnO2 depend on the preparation method and subsequent treatment and aging.Three different recipes were used to prepare δ-MnO2. Methods involving a redox reaction between Mn2+ and Mn7+ at neutral pH (δ-MnO2-redox), and reduction of Mn7+ at low pH (δ-MnO2-red), yielded compounds with characteristics in agreement with literature data; they also have a high adsorption capacity for Cu. A method involving oxidation of Mn2+ at high pH yielded a δ-MnO2(ox), with some variant characteristics and a lower adsorption capacity for Cu.An artificial aging process, using heat treatment at neutral pH, produced cryptomelane from δ-MnO2(ox), but not from δ-MnO2(redox) or δ-MnO2(red). Conversion of δ-MnO2(redox) to cryptomelane and loss of approximately one-half of the adsorption capacity, as a result of a natural aging process, can be avoided for at least four years if the K content is 10% in the solid, and the solid is stored at low temperature. Potassium content, and not a low pH, appears to control the conversion to cryptomelane.Adsorption capacity of δ-MnO2 for Cu appears to be related to the K and H2O content of the solid, which is structure dependent.Because of their higher adsorption capacity for Cu, δ-MnO2(redox) or δ-MnO2(red) are more suitable for trace metal studies in natural waters, than δ-MnO2(ox). 相似文献
20.
Please refer to the attachment(s) for more details 相似文献