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1.
In this paper, I analyze the connections made between women and water in a Rajasthani drinking water supply project as a significant part of drinking water’s commodification. For development policy makers, water progressing from something free to something valued by price is inevitable when moving economies toward modernity and development. My findings indicate that water is not commodified simply by charging money for it, but through a series of discourses and acts that link it to other “modern” objects and give it value. One of these objects is “women”. I argue that through women’s participation activities that link gender and modernity to new responsibilities and increased mobility for village women involving the clean water supply, a “traditional” Rajasthani woman becomes “modern”. Water, in parallel, becomes “new”, “improved” and worth paying for. Women and water resources are further connected through project staff’s efforts to promote latrines by targeting women as their primary users. The research shows that villagers applied their own meanings to latrines, some of which precluded women using them. This paper fills a gap in feminist political ecology, which often overlooks how gender is created through natural resource interventions, by concerning itself with how new meanings of “water” and “women” are mutually constructed through struggles over water use and its commodification. It contributes to critical development geography literatures by demonstrating that women’s participation approaches to natural resource development act as both constraints and opportunities for village constituents. It examines an under-explored area of gender and water research by tracing village-level struggles over meanings of latrines.  相似文献   

2.
Onshore–offshore seismic refraction profiling allows for the determination of crustal and mantle structures in the transition between continental and oceanic environments. Islands and narrow landmasses have the unique geometry of allowing for double-sided onshore–offshore experiments that favor the construction of composite “super-gathers” using the acquisition of onshore–offshore and ocean-bottom seismometer receiver gathers, land explosion shot gathers, and near-vertical incidence multichannel seismic (MCS) profiling. A number of sites at plate boundaries are amenable to the application of double-sided onshore–offshore imaging, including the Indo-Australian/Pacific transform boundary on South Island, New Zealand. By comparing the ratio of island width to mantle refraction (Pn) “maximum” crossover distance, using nondimensional distances, we provide an indicator of raypath “coverage” for crustal illumination. Islands or narrow land masses whose widths are less than twice their maximum crossover distance are candidates for double-sided onshore–offshore experiments. The SIGHT (South Island GeopHysical invesTigation) experiment in New Zealand is located where the width of South Island is sufficiently narrow with respect to its crustal thickness that a double-sided onshore–offshore experiment allows for complete crustal imaging of the associated plate boundary.  相似文献   

3.
J. -B. Edel   《Tectonophysics》2003,363(3-4):225-241
Generally, the lack of bedding criteria in basement units hampers the interpretation of paleomagnetic results in terms of geotectonics. Nevertheless, this work demonstrates that successive remagnetizations recorded in Early Carboniferous metamorphic and plutonic units, without clear bedding criteria, can be used to constrain a polyphased tectonic evolution consisting of a regional clockwise rotation, followed by a folding phase, a tilting phase and a second regional clockwise rotation.Metamorphic, ultrabasic, tonalitic and granitic rocks from different parts of Limousin (western French Massif central; 45.5°N/1.25°E), which underwent metamorphism during Devonian–Early Carboniferous or were intruded in the Early–Middle Carboniferous, were sampled in order (a) to identify the magnetic overprinting phases and the related tectono-magmatic events and (b) to constrain the regional and plate tectonic evolution of Limousin. Paleomagnetic results from 32 new and 26 sites investigated previously show that at least 90% of the magnetization isolated in rocks older than 330 Ma are overprints. In agreement with results from adjacent areas of the Variscan belt, the major overprinting phases occurred: (a) in the last stages of the major exhumation phase [332–328 Ma; mean Virtual Geomagnetic Pole (VGP) “Cp”: 37°N/70.5°E], (b) during the post-collisional syn-orogenic extension (325–315 Ma; VGP “B”: 11°N/114°E), (c) in the Latest Carboniferous and Early Permian (VGP “A1”: 27°N/149°E) and (d) in the Late Permian (VGP “A”: 48°N/146°E). The Middle–Late Carboniferous overprints “Cp” and “B” are contemporaneous with emplacement of leucogranitic, crustal derived plutons, and probably result from the hydro-thermal activity related to the magmatism. The drift from “Cp” directions to “B” directions implies that after 330 Ma, Limousin underwent a clockwise rotation by 65°, together with the Central Europe Variscides. The “Bt” components, the VGPs of which deviate from the mean apparent polar wander path (APWP) of the belt, are interpreted as “B” overprints tilted during Late Variscan tectonics, that is, in the time range 325–315 Ma. The first and most important generation of “Bt” overprints was tilted during NW–SE folding associated with NE–SW shortening, updoming and emplacement of leucogranitic plutons. The second generation reveals southeastward tilting due to NE-striking normal faulting. The drift from “B” to “A1” directions implies that Limousin has participated to the second clockwise rotation by 40° of the whole belt in Westphalian times.  相似文献   

4.
Using open-ended interviews to conduct research on foreign elites raises methodological questions which conducting research on non-foreign elites and foreign non-elites does not. In this paper I first reflect upon some of the practical issues I have encountered when conducting interviews with members of foreign elites. I then examine the issue of positionality to suggest that the dualism of “insider” knowledge and status versus “outsider” knowledge and status is not as stable as it is often assumed to be, and that it should not be presumed that an “insider” will necessarily produce “better” knowledge than will an “outsider” simply by dint of their positionality. Indeed, given that the interview process is about constructing social meaning – a process that involves both the researcher and the source – in many ways such a dualism is meaningless.  相似文献   

5.
Amino acid enantiomeric (D/L) ratios in the mollusk Mercenaria are compared with recently published biostratigraphic and/or U-series solitary coral data from 22 Quaternary localities on the central and southern Atlantic Coastal Plain. In all cases, local relative aminostratigraphic sequences are consistent with relative ages inferred from U-series or biostratigraphic data, although occasionally more depositional events are recognized by aminostratigraphic than biostratigraphic methods. However, if the U-series data are used as age calibrations for the D/L values, latitudinal trends of “isochronous” D/L values are highly variable and conflict with trends expected from the present temperature gradient, which is smooth and nearly linear between 45° and 25° N. Age estimation can be performed independently of the U-series data using a kinetic model that relies on the assumption that Pleistocene temperature gradients have also been smooth functions of latitude, although significantly steeper than the present temperature gradient. Within the uncertainties of this assumption, kinetic model age estimates for localities in the coastal plain fall into the following groups: 70,000–130,000 yr, 200–250,000 yr, 300,000–400,000 yr, 500,000–600,000 yr, 700,000–800,000 yr, and > 1,000,000 yr. Major conflicts between these model age estimates are observed for localities near Charleston, South Carolina and in central Virginia. These conflicts could indicate that the basic temperature assumptions of aminostratigraphy are incorrect, and that apparent local aminostratigraphic sequences (clusters of different D/L values) could be due to factors other than age difference. Alternatively, some of the U-series dates may be only minimum ages for these localities.  相似文献   

6.
The Jinshajiang Suture Zone is important for enhancing our understanding of the evolution of the Paleo-Tethys and its age, tectonic setting and relationship to the Ailaoshan Suture Zone have long been controversial. Based on integrated tectonic, biostratigraphic, chemostratigraphic and isotope geochronological studies, four tectono-stratigraphic units can be recognized in the Jinshajiang Suture Zone: the Eaqing Complex, the Jinshajiang Ophiolitic Melange, the Gajinxueshan “Group” and the Zhongxinrong “Group”. Isotope geochronology indicates that the redefined Eaqing Complex, composed of high-grade-metamorphic rocks, might represent the metamorphic basement of the Jinshajiang area or a remnant micro-continental fragment. Eaqing Complex protolith rocks are pre-Devonian and probably of Early–Middle Proterozoic age and are correlated with those of the Ailaoshan Complex. Two zircon U–Pb ages of 340±3 and 294±3 Ma, separately dated from the Shusong and Xuitui plagiogranites within the ophiolitic assemblage, indicate that the Jinshajiang oceanic lithosphere formed in latest Devonian to earliest Carboniferous times. The oceanic lithosphere was formed in association with the opening and spreading of the Jinshajiang oceanic basin, and was contiguous and equivalent to the Ailaoshan oceanic lithosphere preserved in the Shuanggou Ophiolitic Melange in the Ailaoshan Suture Zone; the latter yielded a U–Pb age of 362±41 Ma from plagiogranite. The re-defined Gajinxueshan and Zhongxinrong “groups” are dated as Carboniferous to Permian, and latest Permian to Middle Triassic respectively, on the basis of fossils and U–Pb dating of basic volcanic interbeds. The Gajinxueshan “Group” formed in bathyal slope to neritic shelf environments, and the Zhongxinrong “Group” as bathyal to abyssal turbidites in the Jinshajiang–Ailaoshan back-arc basin. Latest Permian–earliest Middle Triassic synorogenic granitoids, with ages of 238±18 and 227±5–255±8 Ma, respectively, and an Upper Triassic overlap molasse sequence, indicate a Middle Triassic age for the Jinshajiang–Ailaoshan Suture, formed by collision of the Changdu-Simao Block with South China.  相似文献   

7.
The Glueckstadt Graben is one of the deepest post-Permian structures within the Central European Basin system and is located right at its “heart” at the transition from the North Sea to the Baltic Sea and from the Lower Saxony Basin to the Rynkoebing–Fyn High.The Mesozoic to recent evolution is investigated by use of selected seismic lines, seismic flattening and a 3D structural model. A major tectonic event in the latest Middle–Late Triassic (Keuper) was accompanied by strong salt tectonics within the Glueckstadt Graben. At that time, a rapid subsidence took place within the central part, which provides the “core” of the Glueckstadt Graben. The post-Triassic tectonic evolution of the area does not follow the typical scheme of thermal subsidence. In contrast, it seems that there is a slow progressive activation of salt movements triggered by the initial Triassic event. Starting with the Jurassic, the subsidence centre partitioned into two parts located adjacent to the Triassic “core.” In comparison with other areas of the Central European Basin system, the Glueckstadt Graben was not strongly affected by additional Jurassic and Cretaceous events. During the late Jurassic to Early Cretaceous, the area around the Glueckstadt Graben was affected by relative uplift with regional erosion of the elevated relief. However, subsidence was reactivated and accelerated during the Cenozoic when a strong subsidence centre developed in the North Sea. During Paleogene and Quaternary–Neogene, the two centres of sedimentation moved gradually towards the flanks of the basin.The data indeed point toward a control of post-Permian evolution by gradual withdrawal of salt triggered by the initial exhaustion along the Triassic subsidence centre. In this sense, the Glueckstadt Graben was formed at least partially as “basin scale rim syncline” during post-Permian times. The present day Hamburger, East and Westholstein Troughs are the actual final state of this long-term process which still may continue and may play a role in terms of young processes and, e.g., for coastal protection.  相似文献   

8.
We have developed a significant body of new field-based evidence relating to the history of crustal extension in western Turkey. We establish that two of the NE–SW-trending basins in this region, the Gördes and Selendi Basins, whose sedimentary successions begin in the early Miocene, are unlikely to relate to late-stage Alpine compressional orogeny or to E–W extension of Tibetan-type grabens as previously suggested. We argue instead that these basins are the result of earlier (?) late Oligocene, low-angle normal faulting that created approximately N–S “scoop-shaped” depressions in which clastic to lacustine and later tuffaceous sediments accumulated during early–mid-Miocene time, separated by elongate structural highs. These basins were later cut by E–W-trending (?) Plio–Quaternary normal faults that post-date accumulation of the Neogene deposits. In addition, we interpret the Alaşehir (Gediz) Graben in terms of two phases of extension, an early phase lasting from the early Miocene to the (?) late Miocene and a young Plio–Quaternary phase that is still active. Taking into account our inferred earlier phase of regional extension, we thus propose a new three-phase “pulsed extension” model for western Turkey. We relate the first two phases to “roll-back” of the south Aegean subduction zone and the third phase to the westward “tectonic escape” of Anatolia.  相似文献   

9.
Although “barkinite” has long been studied by many geologists, its geochemical characteristics and environment of deposition are still not known in detail. In order to study the petrography and geochemical characteristics of “barkinite”, coal samples from two Permian coal seams were taken from the Dahe mine, Guizhou Province. The samples were separated into maceral fractions, and then analyzed by microscopical, isotopic, Rock-Eval, and geochemical methods. The microscopical results indicate that “barkinite” occurs as four main types. According to their relationship to other maceral groups, “barkinite” is ostensibly formed under variably dry–wet or oxidizing–reducing conditions. The extract yield, isotope data and Rock-Eval values of “barkinite” are different from other macerals. Microscopical and geochemical results indicate that “barkinite” forms part of the liptinite group.  相似文献   

10.
Modern Tethyan, Mediterranean, and Pacific analogues are considered for several Appalachian, Caledonian, and Variscan terranes (Carolina, West and East Avalonia, Oaxaquia, Chortis, Maya, Suwannee, and Cadomia) that originated along the northern margin of Neoproterozoic Gondwana. These terranes record a protracted geological history that includes: (1) 1 Ga (Carolina, Avalonia, Oaxaquia, Chortis, and Suwannee) or 2 Ga (Cadomia) basement; (2) 750–600 Ma arc magmatism that diachronously switched to rift magmatism between 590 and 540 Ma, accompanied by development of rift basins and core complexes, in the absence of collisional orogenesis; (3) latest Neoproterozoic–Cambrian separation of Avalonia and Carolina from Gondwana leading to faunal endemism and the development of bordering passive margins; (4) Ordovician transport of Avalonia and Carolina across Iapetus terminating in Late Ordovician–Early Silurian accretion to the eastern Laurentian margin followed by dispersion along this margin; (5) Siluro-Devonian transfer of Cadomia across the Rheic Ocean; and (6) Permo-Carboniferous transfer of Oaxaquia, Chortis, Maya, and Suwannee during the amalgamation of Pangea. Three potential models are provided by more recent tectonic analogues: (1) an “accordion” model based on the orthogonal opening and closing of Alpine Tethys and the Mediterranean; (2) a “bulldozer” model based on forward-modelling of Australia during which oceanic plateaus are dispersed along the Australian plate margin; and (3) a “Baja” model based on the Pacific margin of North America where the diachronous replacement of subduction by transform faulting as a result of ridge–trench collision has been followed by rifting and the transfer of Baja California to the Pacific Plate. Future transport and accretion along the western Laurentian margin may mimic that of Baja British Columbia. Present geological data for Avalonia and Carolina favour a transition from a “Baja” model to a “bulldozer” model. By analogy with the eastern Pacific, we name the oceanic plates off northern Gondwana: Merlin (≡Farallon), Morgana (≡Pacific), and Mordred (≡Kula). If Neoproterozoic subduction was towards Gondwana, application of this combined model requires a total rotation of East Avalonia and Carolina through 180° either during separation (using a western Transverse Ranges model), during accretion (using a Baja British Columbia “train wreck” model), or during dispersion (using an Australia “bulldozer” model). On the other hand, Siluro-Devonian orthogonal transfer (“accordion” model) from northern Africa to southern Laurussia followed by a Carboniferous “Baja” model appears to best fit the existing data for Cadomia. Finally, Oaxaquia, Chortis, Maya, and Suwannee appear to have been transported along the margin of Gondwana until it collided with southern Laurentia on whose margin they were stranded following the breakup of Pangea. Forward modeling of a closing Mediterranean followed by breakup on the African margin may provide a modern analogue. These actualistic models differ in their dictates on the initial distribution of the peri-Gondwanan terranes and can be tested by comparing features of the modern analogues with their ancient tectonic counterparts.  相似文献   

11.
Northwestern Fujian Province is one of the most important Pre-Palaeozoic areas in the Cathaysia Block of South China. Metavolcano-sedimentary and metasedimentary rocks of different types, ages and metamorphic grades (granulite to upper greenschist facies) are present, and previously were divided into several Formations and Groups. Tectonic contacts occur between some units, whereas (deformed) unconformities have been reported between others. New SHRIMP U–Pb zircon ages presented here indicate that the original lithostratigraphy and the old “Group” and “Formation” terminology should be abandoned. Thus the “Tianjingping Formation” was not formed in the Archaean or Palaeoproterozoic, as previously considered, but must be younger than its youngest detrital zircons (1790 Ma) but older than regional metamorphism (460 Ma). Besides magmatic zircon ages of 807 Ma obtained from metavolcano-sedimentary rocks of the “Nanshan Formation” and 751–728 Ma for the “Mamianshan Group”, many inherited and detrital zircons with ages ranging from 1.0 to 0.8 Ga were also found in them. These ages indicate that the geological evolution of the study area may be related to the assembly and subsequent break-up of the Rodinia supercontinent. The new zircon results poorly constrain the age of the “Mayuan Group” as Neoproterozoic to early Palaeozoic (728–458 Ma), and not Palaeoproterozoic as previously thought. Many older inherited and detrital zircons with ages of 3.6, 2.8, 2.7, 2.6–2.5, 2.0–1.8 and 1.6 Ga were found in this study. A 3.6 Ga detrital grain is the oldest one so far identified in northwestern Fujian Province as well as throughout the Cathaysia Block. Nd isotope tDM values of eight volcano-sedimentary and clastic sedimentary rock samples centre on 2.73–1.68 Ga, being much older than the formation ages of their protoliths and thus showing that the recycling of older crust played an important role in their formation. These rocks underwent high grade metamorphism in the early Palaeozoic (458–425 Ma) during an important tectono-thermal event in the Cathaysia Block.  相似文献   

12.
The Andaman arc in the northeastern Indian Ocean defines nearly 1100 km long active plate margin between the India and Burma plates where an oblique Benioff zone develops down to 200 km depth. Several east-trending seismologic sections taken across the Andaman Benioff Zone (ABZ) are presented here to detail the subduction zone geometry in a 3-D perspective. The slab gravity anomaly, computed from the 3-D ABZ configuration, is a smooth, long-wavelength and symmetric gravity high of 85 mGal amplitude centering to the immediate east of the Nicobar Island, where, a prominent gravity “high” follows the Nicobar Deep. The Slab-Residual Gravity Anomaly (SRGA) and Mantle Bouguer Anomaly (MBA) maps prepared for the Andaman plate margin bring out a double-peaked SRGA “low” in the range of − 150 to − 240 mGal and a wider-cum-larger MBA “low” having the amplitude of − 280 to − 315 mGal demarcating the Andaman arc–trench system. The gravity models provide evidences for structural control in propagating the rupture within the lithosphere. The plate margin configuration below the Andaman arc is sliced by the West Andaman Fault (WAF) as well as by a set of sympathetic faults of various proportions, often cutting across the fore-arc sediment package. Some of these fore-arc thrust faults clearly give rise to considerably high post-seismic activity, but the seismic incidence along the WAF further east is comparatively much less particularly in the north, although, the lack of depth resolution for many of the events prohibits tracing the downward continuity of these faults. Tectonic correlation of the gravity-derived models presented here tends to favour the presence of oceanic crust below the Andaman–Nicobar Outer Arc Ridge.  相似文献   

13.
Several definitions of stromatolites are discussed and Kalkowsky's most important statements about stromatolites are translated from German to English. A new definition for stromatolites is proposed, namely “Stromatolites are laminated rocks, the origin of which can clearly be related to the activity of microbial communities, which by their morphology, physiology and arrangement in space and time interact with the physical and chemical environment to produce a laminated pattern which is retained in the final rock structure”. Unconsolidated laminated systems, clearly related to the activity of microbial communities and often called “recent stromatolites” or “living stromatolites”, are defined as “potential stromatolites”.The main microbial activities which are important in the formation of potential stromatolites and stromatolites are described and examples of stromatolites of various types, including iron stromatolites, are also described.  相似文献   

14.
This report extends previous work ([Louda et al., 1998a] and [Louda et al., 1998b]. Chlorophyll degradation during senescence and death. Organic Geochemistry 29, 1233–1251.) in which we detailed type-I (alteration) and -II (destruction) degradation of chlorophyll with representative fresh water phytoplankton. The present study covers similar experiments with marine phytoplankton, namely, a cyanobacterium (“ANA” Anacystis sp), a coccolithophore (“COC” Coccolithophora sp.), a dinoflagellate (“GYM” Gymnodinium sp.) and two diatoms (“CYC” Cyclotella meneghiniana and “THAL” Thalassiosira sp.). Mg loss (‘pheophytinization') was rapid and continuous in all species under room-oxic conditions and slow or sporadic under anoxic conditions. The proportion of dephytylated pigments (pheophorbides-a, chlorophyllides-a), relative to the phytylated forms (chlorophyll-a, pheophytins-a), increased over the first year under room-oxic conditions and in room-anoxic conditions only in “CYC”. Pheophorbide-a was converted to pyropheophorbide-a within 15 months only in “THAL” and “ANA”, and slightly in “COC”. After 9–15 months of oxic incubation, “COC” was found to contain traces of purpurin-18 phytyl ester. Consideration of carotenoid pigments is also included herein. All fucoxanthin containing species, except “THAL”, exhibited conversion of fucoxanthin to fucoxanthinol in room-oxic conditions. Diadinoxanthin was rapidly de-epoxidized to give diatoxanthin within the first 2–4 weeks. Diatoxanthin then disappeared from all species by 15 months with a concurrent increase in a pigment which we tentatively identify as a cis-zeaxanthin. Incubations of pure cultures are found to be an effective way by which to model the early type-I reactions for both chlorophylls and carotenoids. The influence of oxygen during senescence-death and the onset of early diagenesis is of paramount importance. The absence of oxygen and, by inference, aerobic microbiota, retards the breakdown of these pigments dramatically.  相似文献   

15.
A cross-section of earthquakes located in northeastern Japan is presented by using pPdepths reported by the International Seismological Centre. Travel-time corrections for the water layer were used to recompute pP-depths of earthquakes located below the sea regions. Seven new focal-mechanism solutions, based on teleseismic and Japanese data, were determined for this region. The reconstructed cross-section shows a double seismic zone at intermediate depths of 80–150 km. Earthquakes located within the upper seismic plane are characterized by down-dip compression while those in the lower plane, located about 35 km below the other seismic plane, are characterized by down-dip extension. These observations suggest that, at these depths, stresses attributable to a simple “unbending” of a plate may contribute to the generation of earthquakes in addition to stresses generated by the gravitational sinking of the lithosphere. A detailed cross-section of shallow earthquakes in the same area between the trench and eastern coast of northeastern Honshu is presented along with focal-mechanism solutions. This cross-section delineates more clearly the seismic zones characterized by normal and low-angle thrust faulting.  相似文献   

16.
Most Quaternary research in Canada during the first half of the twentieth century focused on Pleistocene glaciation. Given the dramatic shifts in climate during the Pleistocene, it is not surprising that the Holocene was viewed as a time of benign climate. Holocene climate variability was first recognized around the middle of the century when paleoecologists found evidence that the early part of the epoch was warmer and drier than the later part. In 1970s and 1980s, another generation of geologists, geographers, and botanists began to recognize more complexity in Holocene climate and vegetation in western Canada. Several millennial-scale glacier “advances” postdating the early Holocene warm interval were defined, including the Garibaldi Phase (6.9–5.6 ka), the Tiedemann–Peyto Advance (3.5–1.9 ka), and the Little Ice Age (AD 1200–1900). Subsequently, application of dendrochronological techniques and stratigraphic studies in glacier forefields showed that the Little Ice Age was itself more complex than previously thought. During that 700-year period, glaciers repeatedly advanced and retreated in response to climatic variability on time scales ranging from centuries to decades. Recent work shows that the glacier record of the Garibaldi Phase and the Tiedemann and Peyto advances are similar in complexity to the Little Ice Age, with multiple advances of glaciers separated by intervals of more restricted ice cover. Researchers have also identified other times in the Holocene when glaciers expanded from restricted positions – 8.20, 4.90–3.80, and 1.70–1.40 ka. Continued research undoubtedly will reveal additional complexities, but with what is currently known the appropriateness of terms such as “Tiedemann Advance,” “Peyto Advance,” and “Little Ice Age” can be questioned. Only short periods of time separate these episodes as currently defined, and it seems likely that intervals of restricted glacier cover within each of these millennial-length intervals are just as long as the intervals separating them.  相似文献   

17.
The Tiámaro deposit in Michoacán state has been dated as Lower Cretaceous (Valanginian), though most of the porphyry deposits in central Mexico were dated or have an attributed Eocene–Oligocene age. The host rocks belong to a volcanoplutonic complex overlain by red conglomerates. These rocks were intruded by pre-Valanginian plutonic and hypabissal rocks. Propylitic, phyllic, and argillic alteration assemblages developed, and their superimposition draws the evolution of the deposit. Stage I is represented by propylitic assemblages, stage II contains the main ore forming stockworks and both phyllic and argillic assemblages, and stage III contains late carbonatization assemblages. The obtained temperatures and salinities from inclusion fluids are low for a porphyry-type deposit, but we interpret that the known part of the deposit represents the shallow portion of a bigger deposit. The evolution of mineralizing fluids draws a dilution trend of brines from “porphyry-like” to “epithermal-like” stages. The richest ore zone is roughly located between the 300 and 350 °C isotherms, though unnoticed resources may occur at depth.  相似文献   

18.
Jody Emel  Matthew T. Huber   《Geoforum》2008,39(3):1393-1407
Natural resource investment in the mining sector is often mediated through conflicts over rent distribution between corporate capital and landowner states. Recent rounds of neoliberal policy promoted by the World Bank have highlighted the need for landowner states to offer incentives in order to attract “high risk” capital investment. In Sub-Saharan Africa, in particular, countries have been pushed to offer attractive fiscal terms to capital, thereby lowering the proportion traditionally called rent. This paper examines how the concept of “risk” has been mobilized to legitimate such skewed distributional arrangements. While certain conceptions of social and ecological “risk” have been prevalent in political and social theoretic discourse on mining, such focus elides the overwhelming contemporary power of our notion of “neoliberal risk” – or the financial/market risks – in actually setting the distributional terms of mineral investment. We illustrate our argument by examining the nexus of World Bank mining policy promotion and Tanzanian policy in the late 1990s meant to attract foreign direct investment in gold production. In closing, we suggest that just as “risk” is used to legitimate attractive fiscal terms for investment, recent events highlight how skewed distribution of benefits may set into motion risks that corporate capital had not bargained for.  相似文献   

19.
The Owl Creek Gold Mine is located in Hoyle Township, approximately 18 km northeast of Timmins, Ontario, Canada. The open-pit mine exposes a sequence of altered and mineralized mafic tholeiitic volcanics bounded to the north and south by greywacke and argillite. Gold occurs in the free state in quartz veins, often with graphite, and as fine gold on surfaces of, and within fractures in, pyrite.The study was designed to determine the distribution and distance of transport of Au in overburden down-ice from subcropping Au mineralization. This required an understanding of the glacial history of the area.The Quaternary stratigraphy at Owl Creek was studied and sampled by means of 17 sonic and 15 reverse-circulation overburden drill holes near the open pit, and several overburden exposures in the open-pit walls. Nonmagnetic heavy-mineral concentrates (specific gravity >3.3) were made from the <2000 μm (−10 mesh) fraction of all overburden samples from the drill hole and section sampling. The heavy-mineral concentrates were analyzed for Au by neutron activation. A till pebble lithology study was done on the >2000 μm (−10 mesh) fraction of the sonic drill core.Our stratigraphic studies indicate that there were three major Wisconsinan (Weichselian) ice advances and one minor, late readvance in the Timmins area. The transport and deposition of sediments comprising the “Oldest”, “Older”, Matheson and Cochrane stratigraphic “packages” (oldest to youngest) are related to three ice advances and one readvance which moved towards 240° ± 10°, 150° ± 5°, 170° ± 5° and 130° ± 5°, respectively.Geochemically anomalous levels of Au in the overburden define two dispersal trains down-ice of the Owl Creek Gold Mine. One, in the “Older” lodgement till, is 400–500 m long. The other in Matheson ablation and waterlain tills, is approximately 700 m long.The till pebble lithology study showed that pebble counting can be used to approximate bedrock contacts, but may not necessarily identify the source rock type of the matrix.  相似文献   

20.
Leping coal is known for its high content of “barkinite”, which is a unique liptinite maceral apparently found only in the Late Permian coals of South China. “Barkinite” has previously identified as suberinite, but on the basis of further investigations, most coal petrologists conclude that “barkinite” is not suberinite, but a distinct maceral. The term “barkinite” was introduced by (State Bureau of Technical Supervision of the People's Republic of China, 1991, GB 12937-91 (in Chinese)), but it has not been recognized by ICCP and has not been accepted internationally.In this paper, elemental analyses (EA), pyrolysis-gas chromatography, Rock-Eval pyrolysis and optical techniques were used to study the optical features and the hydrocarbon-generating model of “barkinite”. The results show that “barkinite” with imbricate structure usually occurs in single or multiple layers or in a circular form, and no definite border exists between the cell walls and fillings, but there exist clear aperture among the cells.“Barkinite” is characterized by fluorescing in relatively high rank coals. At low maturity of 0.60–0.80%Ro, “barkinite” shows strong bright orange–yellow fluorescence, and the fluorescent colors of different cells are inhomogeneous in one sample. As vitrinite reflectance increases up to 0.90%Ro, “barkinite” also displays strong yellow or yellow–brown fluorescence; and most of “barkinite” lose fluorescence at the maturity of 1.20–1.30%Ro. However, most of suberinite types lose fluorescence at a vitrinite reflectance of 0.50% Ro, or at the stage of high volatile C bituminous coal. In particular, the cell walls of “barkinite” usually show red color, whereas the cell fillings show yellow color under transmitted light. This character is contrary to suberinite.“Barkinite” is also characterized by late generation of large amounts of liquid oil, which is different from the early generation of large amounts of liquid hydrocarbon. In addition, “barkinite” with high hydrocarbon generation potential, high elemental hydrogen, and low carbon content. The pyrolysis products of “barkinite” are dominated by aliphatic compounds, followed by low molecular-weight aromatic compounds (benzene, toluene, xylene and naphthalene), and a few isoprenoids. The pyrolysis hydrocarbons of “barkinite” are mostly composed of light oil (C6–C14) and wet gas (C2–C5), and that heavy oil (C15+) and methane (C1) are the minor hydrocarbon.In addition, suberinite is defined only as suberinized cell walls—it does not include the cell fillings, and the cell lumens were empty or filled by corpocollinites, which do not show any fluorescence. Whereas, “barkinite” not only includes the cell walls, but also includes the cell fillings, and the cell fillings show bright yellow fluorescence.Since the optical features and the hydrocarbon-generating model of “barkinite” are quite different from suberinite. We suggest that “barkinite” is a new type of maceral.  相似文献   

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