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1.
The F–(Ba–Pb–Zn) ore deposits of the Zaghouan District, located in NE Tunisia, occur as open space fillings or stratabound orebodies, hosted in Jurassic, Cretaceous and Tertiary layers. The chondrite-normalized rare earth element (REE) patterns may be split into three groups: (i) “Normal marine” patterns characterizing the wallrock carbonates; (ii) light REE (LREE) enriched (slide-shaped) patterns with respect to heavy REE (HREE), with small negative Ce and Eu anomalies, characteristic of the early ore stages; (iii) Bell-shaped REE patterns displaying LREE depletion, as well as weak negative Ce and Eu anomalies, characterizing residual fluids of subsequent stages. The 87Sr/86Sr ratios (0.707654–0.708127 ± 8), show that the Sr of the epigenetic carbonates (dolomite, calcite) and ore minerals (fluorite, celestite) are more radiogenic than those of the country (Triassic, Jurassic, Cretaceous, lower Miocene) sedimentary rocks. The uniformity of this ratio, throughout the District, provides evidence for the isotopic homogeneity and, consequently, the identity of the source of the mineralizing fluids. This signature strongly suggests that the radiogenic Sr is carried by Upper Paleozoic basinal fluids.The δ34S values of barite, associated to mineralizations, are close to those of the Triassic sea water (17‰). The δ34S values of sulfide minerals range from − 13.6‰ to + 11.4‰, suggesting two sulfur-reduced end members (BSR/TSR) with a dominant BSR process.Taking account of the homogeneity in the Pb-isotope composition of galenas (18.833–18.954 ± 0.001, 15.679–15.700 ± 0.001 and 38.690–38.880 ± 0.004, for the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios respectively), a single upper crustal source for base-metals is accepted. The Late Paleozoic basement seems to be the more plausible source for F–Pb–Zn concentrated in the deposits. The genesis of the Zaghouan District ore deposits is considered as the result of the Zaghouan Fault reactivation during the Late Miocene period. 相似文献
2.
T. K. Zlobin 《Doklady Earth Sciences》2018,480(1):599-601
The peculiarities of catastrophic earthquakes that occurred in the Northwest Pacific region on January 13, 2007, and January 15, 2007, east of the Kuril Islands and the Tohoku megaearthquake of March 11, 2011, east of Japan are considered and analyzed. It is revealed that these earthquakes, apart from the fact that they occurred in the transition zone from the Pacific to island arcs and the Eurasian continent, have common features and similar characteristics. The seismotectonic slip in the source of the chronologically first event, the 2006 Kuril earthquake, was a gentle thrust, while that of the second event of January 13, 2007, was a downthrow beneath the Kuril deep trench. 相似文献
3.
K. S. R. Murthy V. Subrahmanyam A. S. Subrahmanyam G. P. S. Murty K. V. L. N. S. Sarma 《Natural Hazards》2010,55(2):167-175
The South Indian (Peninsular) Shield which includes both the Eastern and Western Continental Margins of India is not as stable
as it was originally thought of. The importance of intraplate seismicity within this Shield has recently been realized with
some devastating earthquakes that occurred during the last few decades. It is also significant to note that most of the Precambrian
tectonic lineaments in this Shield are oriented in either a NW–SE or W–E direction, joining the eastern offshore. In contrast,
the western margin has an elevated coast, associated with a linear coast parallel escarpment, particularly on the southern
side, superimposed by Deccan Trap volcanics on the northern side. The fault reactivation and the associated seismicity are
hence more predominant on the east coast. Recent geophysical studies delineated land–ocean tectonics (LOTs) over the eastern
margin, in some cases associated with moderate seismicity as a result of the compressional stress acting on the Indian Plate.
Though the Eastern Continental Margin of India (ECMI) is considered as a passive margin, coastal seismicity due to the reactivation
of the pre-existing tectonic lineaments extending offshore represents a potential natural hazard. In this context, the ECMI
appears to be much more vulnerable compared to its counterpart on the west. 相似文献
4.
《矿物岩石地球化学通报》2007,26(2):207-208
The French Society of Mineralogy and Crystallography is honoured to be invited to give a short presentation of its activity to the Chinese Society for Mineralogy,Petrology and Geochemistry.BRIEF HISTORY AND SOME FRENCH FOUNDERS OF MINERALOGY 相似文献
5.
Kosakowski Paweł Kotarba Maciej J. Piestrzyński Adam Shogenova Alla Więcław Dariusz 《International Journal of Earth Sciences》2017,106(2):743-761
International Journal of Earth Sciences - We present geochemical characteristics of the Lower Palaeozoic shales deposited in the Baltic Basin and Podlasie Depression. In the study area, this strata... 相似文献
6.
7.
H. Z. Abidin R. J. Davies M. A. Kusuma H. Andreas T. Deguchi 《Environmental Geology》2009,57(4):833-844
Global positioning system (GPS) and satellite-based InSAR (Interferometric Synthetic Aperture Radar) measurements of the subsidence
and uplift of a populated area of Sidoarjo, East Java are due to the eruption of the Lusi mud volcano (2006–present). These
data are the first direct quantitative measurements of deformation due to the growth of a mud volcano edifice. The GPS data
were recorded over periods of a few hours to several months and show that between June 2006 and September 2007, the earth’s
surface has been subsiding at rates of 0.1–4 cm/day. Maximum rates of subsidence occurred in an area 300–400 m to the northwest
of the main mud volcano vent. Horizontal displacements were 0.03–0.9 cm/day and were also towards this area. In general uplifts
of up to 0.09 cm/day were recorded in areas outside of the edifice. Changes in elevation measured using satellite imagery
(InSAR technique) provide regional datasets of subsidence and uplift. They confirm that during the first year a roughly circular
area was undergoing sag-like subsidence centered to the northwest of the main vent and that uplift was occurring 3–4 months
after the initiation of the eruption due to the movement Watukosek fault system. Subsidence occurred due to the weight of
mud and man-made dams and the collapse of the overburden due to removal of mud from the subsurface. Assuming constant rates
of subsidence of 4 cm/day, then in the centre of the edifice there would be up to 44 m of subsidence in 3 years, and up to
16 m in 10 years. The mud volcano is now in a self-organizing state with new fluid conduits forming as a result of the collapse.
An erratum to this article can be found at 相似文献
8.
Geology of Ore Deposits - Paragenetic associations of tetrahedrite-(Zn) and sphalerite are distinguished in the Teremki gold-ore deposit. The chemical composition of coexisting minerals of this... 相似文献
9.
10.
Pinios (Peneus) River (Central Greece): Hydrological — Geomorphological elements and changes during the quaternary 总被引:1,自引:0,他引:1
George Migiros George D. Bathrellos Hariklia D. Skilodimou Theodoros Karamousalis 《Central European Journal of Geosciences》2011,3(2):215-228
The Pinios River is the third longest river of Greece. It drains the entire drainage basin of Thessaly (eastern part of Central Greece), part of which is the largest plain of the country. In this research the hydrological, geomorphological and geological characteristics of the riverine area of Pinios were studied. Classification and grouping of these characteristics were then carried out, which led to the segmentation of the Pinios River into seven sections, each one with its own set of thematic data. These sets assign separate functions and evolutions of the river system during the Quaternary. Specifically, the basin of the present Pinios River, before its evolution into a river basin, comprised three separate and independent systems. The present Pinios River emerged as a river system from the merging of the lacustrine paleoenvironments along with the major tributaries that drained large parts of the present hydrological basin and as soon as the karstic openings of the central hill valley and the Tempi valley took place during the Quaternary. The followed methodology for the segmentation of the river can be used for the study of heterogeneous river systems. 相似文献
11.
Spiridonov E. M. Filimonov S. V. Semikolennykh E. S. Korotaeva N. N. Krivitskaya N. N. 《Geology of Ore Deposits》2020,62(7):638-651
Geology of Ore Deposits - Chevkinite-(Се) and perrierite-(Се), which are characteristic minerals of alkaline igneous rocks and high-temperature alkaline alterations, are... 相似文献
12.
Paleogeographical Distribution and Stratigraphical Range of the Lower Triassic Claraia,Pseudoclaraia and Eumorphotis(Bivalvia) 总被引:1,自引:0,他引:1
Yin Hongfu 《中国地质大学学报(英文版)》1990,(1)
On the basis of a worldwide review of Claraia,Pseudoclaraia andEumorphotis,especially their important species,two range zones are recog-nized:the Pseudoclaraia wangi range zone——Upper Griesbachia——and the Claraia stachei-C.aurita-Eumorphotis multiformis acme zone——Upper Griesbachian to Lower Smithian .This result revises both the traditional Chinese concept regarding these fossils as limited in Lower Scythian andthe viewpoint of some Eurasian researchers who hold Eumorphotis multifor-mis to be Upper Scythian.The paleogeographical distribution of the three genera is controlledprimarily by temperature(latitude)and secondarily by physiographic separa-tions.Distribution of these fossils is subdivided into four realms and five prov-inces.The Eastern Asia province of the Tethys realm is suggested as thesource area of these fossils.The striking contrast between the composition ofthe species along the southern and northern margins of the Tethys,togetherwith other distributional characters,supports the pla 相似文献
13.
Kálmán T?r?k 《International Journal of Earth Sciences》2012,101(6):1581-1597
Rarely occurring clinopyroxene-plagioclase bearing, felsic granulite and skarn xenoliths were studied from the mantle and crustal xenolith-bearing alkaline basaltic and pyroclastic localities of the Bakony–Balaton Highland Volcanic Field (W-Hungary). Geobarometry and geothermometry of the xenoliths made it possible to categorise them in three groups according to their depth of formation. The first group formed in the lower crust together with mafic and metasedimentary granulites. The second group represents magmatic intrusions of the middle crust, and the third one comprises contact metamorphic rocks of relatively shallow origin. The calculated pressure difference from the core and rim compositions of plagioclase and clinopyroxene as well as garnet breakdown reactions in some xenoliths show evidence for pressure decrease due to crustal thinning both in lower crustal and middle crustal xenoliths during formation of the Pannonian Basin. Fluid inclusion studies reveal the dominance of the CO2-rich fluids in the whole crustal section in contrast with fluids found in mafic garnet-bearing xenoliths. Crustal stratigraphy was constructed for the periods prior to the extension and after the extension on the basis of geobarometry and geophysical data. On the basis of mineral stabilities and geothermo-barometry, we estimated that the pre-extensional thickness of the lower and upper crust may have been 27–34 and 26–28?km, respectively. Comparison of pre-extensional and present-day thickness of the lower and upper crust indicate that thinning affected both the lower and the upper portion of the crust but on a different scale. The calculated thinning factors are between 2.25 and 3.4 for the lower crust and 1.3–1.56 for the upper crust. 相似文献
14.
Franco Rolfo Bruno Lombardo Roberto Compagnoni Patrick Le Fort Yves Lemennicier Arnaud Pêcher 《Geodinamica Acta》2013,26(5):251-270
AbstractMetamorphism of the Askore Amphibolite, metabasaltic and metasedimentary medium-grade hornblendebearing schists at the northernmost portion of the Ladakh Terrane and of the Shyok Suture Zone, mainly a low-grade volcano-sedimentary series, has been studied in the area between the Chogo Lungma glacier and the Indus river halfway between Skardu and Rondu.In the Askore Amphibolite the peak assemblage in the amphibolite facies defines the regional metamorphic foliation, and is overprinted by a later static recrystallization at comparable P-T conditions. In spite of similar peak temperatures (630–650°C), geobarometry based on amphibole composition reveals a marked difference between garnet – epidote – andesine amphibolites exposed just above the Main Mantle Thrust at the head of Turmik valley, which equilibrated at high pressures (about 10 kbar) in late Miocene (Tortonian), and biotite – epidote – oligoclase amphibolites outcropping at the mouth of Turmik valley, which equilibrated at pressures of c. 6 kbar before late Eocene (Priabonian).The Dasu Ultramafite and other smaller lens-shaped bodies of low- to medium-grade metaperidotite separate the Ladakh Terrane from the Shyok Suture Zone. They are antigorite serpentinites, often with talc and magnesite, in which relict cumulitic structures are locally recognisable. The ultramafites may represent remnants of oceanic lithosphere separating the Ladakh-Kohistan island arc from the Asian plate, or they may be deep crustal rocks stripped from the basement of the arc.The mostly greenschist-facies Shyok Suture Zone shows the lithology of a calc-alkaline volcano-sedimentary series. It is supposed to be a remnant of a back arc basin of early Cretaceous age, separating the arc from the southern margin of Asia. Chloritoid, kyanite and biotite have been found in individual thrust sheets occurring at different structural levels and totally subordinate in volume to very low- and low-grade rocks. Such sharp differences in mineral paragenesis, together with field evidence of local shear, suggest a complex internal structure for the Shyok Suture Zone. From the head of Chogo Lungma glacier to the Basha valley, close to the contact with the Karakorum Metamorphic Complex, the rocks of the Shyok Suture Zone record a late Miocene metamorphic event at medium pressures and temperatures. Thermobarometric and geochronological evidence suggests that this event can be related to the exhumation and thrusting of the Karakorum metamorphic core over the Shyok Suture Zone. 相似文献
15.
An integrated radio-astrochronological framework of the Agrio Formation in the Andean Neuquén Basin of west-central Argentina provides new constraints on the age and the duration of the late Valanginian through Hauterivian stratigraphic interval. A CA-ID TIMS U-Pb age of 126.97 ± 0.04(0.07)[0.15] Ma is presented here from the upper Hauterivian Agua de la Mula Member of the Agrio Formation. Biostratigraphic data from ammonoids and calcareous nannofossils and this high precision new radioisotopic age, together with three former ones from the same Agrio Formation are combined with new astrochronological data in the Andes. These are correlated with modern cyclostratigraphic studies in the classical sections of the Mediterranean Province of the Tethys, supporting detailed interhemispheric correlations for the Early Cretaceous. We also provide new δ13C data from the Agrio Formation which are compared with records from the classic Tethyan sections. According to our calibration, the minimum in the values in the mid-Hauterivian appears to be synchronous and, thus, another important stratigraphic marker for global correlation. A new duration of 5.21 ± 0.08 myr is calculated for the Hauterivian Stage, starting at 131.29 ± 0.19 Ma and ending at 126.08 ± 0.19 Ma. The difference between the duration of the Hauterivian in GTS2016 and in this study is 1.32 myr while the base and top of the GTS2016 Hauterivian differ respectively by 3.40 and 4.69 myr. 相似文献
16.
The kinematic pattern and associated metamorphism of the predominant ductile deformation and the subsequent deformational
stages of the Serbomacedonian metamorphic rocks and granitoids are presented in terms of peri-Tethyan tectonics. A systematic
record of structural and metamorphic data gives evidence of a main top-to-ENE to ESE ductile flow of Cretaceous age (120–90 Ma)
associated with a crustal stretching and unroofing. A subordinate WSW to WNW antithetic sense of movement of the tectonic
top is observed in places. The associated metamorphic conditions are estimated at 4.5–7.5 kbar and 510–580 °C. During Eocene
to Miocene times these fabrics were successively deformed by low-angle extensional De ductile shear zones with top-to-NE and SW sense of movement and brittle shear zones of similar kinematic pattern, suggesting
a transition from ductile to brittle deformation. De deformation was accompanied during its later stages by NW/SE-directed shortening. We also discuss the relation of this Cretaceous–Tertiary
deformation of the Serbomacedonian metamorphic rocks with the Eocene to Miocene ductile, top-to-southwestward crustal shear
of the adjacent Rhodope crystalline rocks. We regard the Serbomacedonian and the Rhodope metamorphic rocks to represent related
metamorphic provinces, the most recent exhumation and cooling history of which is bracketed between the Eocene and Neogene.
Received: 8 December 1998 / Accepted: 19 April 1999 相似文献
17.
The paper examines relations among geomorphological processes and the landforms of the Polická vrchovina Highland in the Bohemian Massif. Geologically, the Polická vrchovina Highland is a part of the Intra-Sudetic Basin on the boundary between Bohemia and Poland. The basin structure of the Highland developed during the neotectonic period. In the outer parts of the Highland, Mesozoic rocks dip gently to the centre of the basin to form cuestas. In the central part, layers are horizontal or subhorizontal. Mesas (Hejda and Osta Mesa) provide evidence of the erosion of the Mesozoic deposits. The relative uplift of the Highland resulted in the incision of the Metuje River and its tributaries. Unloading of rocks and erosion initiated typical geomorphological processes such as deep- seated creep, cambering, rockfalls, landslides and pseudokarst processes. These processes produced some typical forms controlled by rock properties, jointing, relative differences in height and climatic changes in the Tertiary and Quaternary. 相似文献
18.
Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy
and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density
functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width
of the Raman band related to OH stretching modes is ascribed to mode–mode anharmonic coupling due to medium-strength H-bonding.
Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence
of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature
behavior, narrow absorption features at ~2,000 cm−1 and anti-resonance at ~2,966 cm−1 in the IR spectrum are interpreted as overtones of fundamental bending bands. 相似文献
19.
Helmut Tenzer Chan-Hee Park Olaf Kolditz Christopher Ian McDermott 《Environmental Earth Sciences》2010,61(4):853-880
Earth-reservoirs are increasingly exploited today with the extraction of resources, such as heat and hydrocarbons, and the
large-scale emplacement of waste, such as CO2 sequestration. The characterization, site investigation, predictive modeling and long-term monitoring are dependent on the
processes being investigated and modeled. In most cases complex coupled processes have to be addressed in a geologically complex
rock mass system. In this paper we present a conceptual holistic framework known as geomechanical facies linking all the scales
of investigation, characterization and reservoir development methods. We demonstrate this concept on the work undertaken during
the design and development of the enhanced geothermal systems (EGS) systems at the forefront of European Hot-Dry-Rock (HDR)
technology, Soultz-sous-Forêts (France) and Spa Urach (Germany). Soultz-sous-Forêts is situated within granitic rocks and
an active tectonic graben system in the central part of the Rhine Graben. It presents conditions of lithology, temperature,
stress, hydraulics and geochemistry that are very different from those at Spa Urach, located in a very dense gneiss formation
in the South German crystalline complex. Spa Urach exhibits more elastic behavior and is set tectonically within an almost
inactive strike-slip stress field described in more detail in Sects. “Drill core analysis” and “Hydraulic stimulation at Spa Urach”. This paper compares the exploration and field development methods used at these two sites against the back drop of the
geomechanical facies concept. Issues addressed include the key parameters for flow and heat transport properties, coupled
hydro-mechanical process identification, the success of the HDR reservoir as a heat exchanger and exploration techniques applicable
to the different facies. Identification of the key geomechanical facies gives an indication as to which technologies will
prove more efficient in the application of HDR technology. The results of this study will hopefully help in developing heat
recovery schemes for the long-term economical operation of future HDR plants and EGS as well as assist in the understanding
of engineered geosystems. 相似文献
20.
Chen D. 《大地构造与成矿学》2015,(1):110-127
After years of prospecting and mining of the basaltic copper deposits in the border area of Yunnan-Guizhou provinces, many people think the potential of metallogenic prospect is dismay and the deposits are of small sized. However, some researchers proposed in 2002 that these deposits have characteristics similar to those of the Keweenaw copper deposits, and thus their significance is worthy of further consideration. To investigate the resource potential in the region, we carried out a comparative study of the deposits in the two regions. The results show that the existence of redbed may be an important facor controlling the potential of copper mineralization. Therefore, we suggest that the native copper mineralization in the mid-low Triassic sandrocks demands further investigation and it is promising for metallogenic prospecting. ©, 2015, Science Press. All right reserved. 相似文献