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1.
In the study area (the Upper Rhine Lowlands and the southern Black Forest), colluvial and alluvial sediments could be dated with the aid of 14C analysis, archaeological finds, pollen analysis and stratigraphic assessments. On the basis of these dated deposits, six different maps have been produced showing the distribution of the colluvial and alluvial sediments for the corresponding archaeological cultural periods. For each of these periods, the intensity of human impact on the environment has been estimated in relation to climatic conditions and different economic activities; for example, woodland clearance and mining activities.  相似文献   

2.
Geoarchaeological investigations at two archaeological excavation sites lead to new results with respect to the Holocene landscape development of an archaeologically important loess landscape of Central Europe. Colluvial and alluvial sediments were sampled during archaeological excavations on the valley edge of the Weiße Elster and dated by means of 14C, TL and dendrochronology, and on the basis of archaeological finds. Thus, for the first time, the development of a valley edge of a river in the Leipzig area, which has been continuously settled for 7300 years, can be reconstructed. The first soil erosion on the valley edge is established towards the end of the Atlantic period. During the High Middle Ages, a colluvial sediment developed. Its deposition time can be limited to between ad 1000 and 1100. The flood loam near Großstorkwitz, which can be stratified by means of the soil and colluvial deposits, originated in the late Sub‐Boreal and early Sub‐Atlantic, as well as after ad 1100. During the first millennium ad, a soil developed in the older flood loam, which indicates a phase of reduced flood loam sedimentation.  相似文献   

3.
The Basin of Phlious in southern Greece is known for its thick colluvial and alluvial deposits from the Holocene. It offers a good opportunity to reconstruct the history of Holocene soil erosion and its interaction with historical farming activities. In this study, we present new results based on optically stimulated luminescence (OSL) dating from the Basin of Phlious. The comparison between OSL and 14C AMS ages shows good agreement, and demonstrates the need for the detection of insufficiently bleached OSL samples in order to obtain accurate results. The discovery of a Neolithic site, buried under thick alluvial deposits, confirms the hitherto postulated Neolithic human impact on the landscape.  相似文献   

4.
This study focuses on the analysis of the structural and textural features of the colluvial (deluvial) deposits in the Suwałki Lake District (NE Poland) and their absolute age. The colluvium has a thickness of up to 150 cm. The dates of the peat under colluvium or lowermost fossil humus-rich horizons point to the ages from 5405±80 BP to 480 BP. Deposition of material at the footslope is a result of a denudation triggered by human action (surface water erosion and tillage erosion) and usually corresponds with the settlement stages. The 14C dating of deposited sediment sometimes indicated to older dates of colluvium then the archaeological evidence available for examined sites. Locally, the overlying fossil humic horizon was older then the lowermost one. The textural features of the colluvial deposits such as: the content of fine fraction, weak sorting and relationship between the mean grain-size (Mz) and the sorting index (σ1) were used to recognize sediment redeposited from the upper part of the slope. Basing on the mineral composition and electrical conductivity of fossil humus horizon it is possible to say whether the soil was degraded or aggraded. These features of the humus-rich horizons occurring between colluvial sediments can be used to explain discrepancy between the radiocarbon dating and archaeological evidence.  相似文献   

5.
P. Birkle 《Geofluids》2016,16(3):565-584
Provenance studies of produced water are essential to trace flow dynamics and reservoir compartmentalization in petroleum systems and to quantify fluid recovery rates from unconventional fracturing. Produced water from a hydraulically fractured well in the Qusaiba Hot Shale in the Northern Exploration Area, Saudi Arabia, was daily monitored and analyzed for water chemistry, and environmental (δ2H, δ13C, δ18OH2O, δ18OSO4, δ34SSO4, δ37Cl, 87Sr/86Sr) and cosmogenic isotopes (3H, 14C, 36Cl), to differentiate from reference fluids of supply water, fracturing fluids, and formation water from adjacent Paleozoic units. Initially, recovered water is composed of fracturing fluids and subsequently replaced by a homogeneous cut of pristine formation water. Formation water is composed of dominant meteoric water (approximately 84 vol%) and minor fossil evaporated seawater. The young 14C‐apparent age between 6000 and 6700 years BP and depleted δ18O/δ2H values for the meteoric component confirm the infiltration of surface water into the Qusaiba Hot Shale interval or adjacent units during the Early Holocene Pluvial Period under cooler and wetter climatic conditions than present, which suggest the presence of a very recent, dynamic hydraulic flow system. 36Cl/Cl ratios between 102 × 10?15 and 31 × 10?15 are ambiguous and can be attributed to atmospheric recharge close to the coast, mixing of 36Cl‐enriched Quaternary meteoric recharge with 36Cl‐depleted fossil seawater, and/or hypogene production by U‐Th‐enriched host rock. Produced waters from Qusaiba Hot Shale are within the compositional range of Na‐Cl‐type formation water from Paleozoic reservoir units in northern Saudi Arabia with salinities from 30 000 to 130 000 mg l?1. As a novel technological approach for exploration wells in Northern Saudi Arabia, multi‐isotopic methods were successfully implemented to quantify flowback volumes from hydraulic fracturing, and to fingerprint pristine formation water or pore water in Paleozoic systems on their provenance, residence time, migration pathways, and secondary alteration processes.  相似文献   

6.
The Middle Son valley in north-central India preserves extensive Quaternary alluvial deposits. A long history of archaeological and geological research in the valley has resulted in the discovery of lithic assemblages ranging from Lower Palaeolithic to microlithic, a rich corpus of fossilised faunal remains, and ash deposits from the 74,000 year-old Toba supereruption. This paper reviews the chronology and stratigraphy of the valley’s Quaternary sediments, and presents a model that hypothesizes the temporal sequence of important lithic assemblages from excavated and surface contexts. Artefacts in these assemblages are analysed and changes in lithic technology through time are described; this evidence is used to propose shifts in hominin behaviour and demographic structure in this region during the Upper Pleistocene. Recognising gaps in our understanding of the Middle Son record, future avenues of research are recommended that will build upon previous research and address questions of palaeoanthropological significance. The Middle Son valley preserves a long and rich record of hominin occupation from all periods of the Palaeolithic that is rarely paralleled by other sites in India.  相似文献   

7.
The kinetics of thermochemical sulfate reduction (TSR) were studied in experiments at 205–250°C, with determination of both sulfate and sulfide at intervals during the runs of up to 430 h. Analysis of the data indicates the reaction to have first‐order kinetics, and extrapolating these data, plus data from the literature, to 150°C gives a range of possible rate constants from 100 to 10?4 year?1. Although the rate law has not been well established, a reasonable estimate allows calculation of the amount of sulfide ore formed as a function of flow conditions and time. It is here concluded that TSR could happen during the formation of Mississippi Valley‐type ore deposits, subject to several caveats.  相似文献   

8.
Abstract

Environmental interpretation is flowering in Denmark. In 1986 it was decided to carry out a three‐year experimental project with 14 environmental interpreters. Today the number of environmental interpreters has grown to 230. The inspiration came from abroad, but the project is established according to Danish cultural and democratic traditions. Some Environmental Interpreters are employed by the State in the National Forests, others by counties, local authorities, museums or ‘green associations’, but they are all linked together in the Environmental Interpreter Service with secretariat in The National Forest and Nature Agency. A modern organisation provides training courses for the interpreters and has developed a series of active interpretation methods in order to make experiencing nature an important tool in modern Danish environmental management and inspire a positive attitude to the future—to sustainable development and management. The aim of setting up an Environmental Interpreter Service was to give people interesting experiences in and knowledge of the countryside and thereby a greater understanding of the complexity of nature, the conditions for agriculture and perhaps an increased environmental consciousness. It was also the hope that if people had a greater understanding of nature, they will love and care for it better. The Brundtland Report ‘Our Common Future, the conference in Rio in 1992 and Agenda 21 has changed the Environmental Interpreters’ work. We have recognised, that it is important to use live Interpreters and not only technical media in this important work. People respond best to personal, face‐to‐face interpretation. The interpreters try to create a love of nature, and at the same time, create an understanding of local and global environmental conditions.  相似文献   

9.
The adsorption onto other minerals of charged gold nanoparticles, carried by gas ascending from the Earth’s interior, is an important component of their transport and deposition in surficial cover such as alluvial, aeolian, and glacial sediments. To simulate the adsorption of these particles, an experiment was conducted in which a flow of air that contained gold nanoparticles was passed upward through a sample of alluvium from the middle–lower reaches of the Yangtze River. These experiments showed that gold nanoparticles are adsorbed on kaolinite, halloysite, goethite, and hematite in the alluvial cover. Both the gold nanoparticles and minerals (i.e., kaolinite, halloysite, goethite, and hematite) carry surface charges that provide them with excellent adsorption properties. This study showed that the specific mineral composition of surficial alluvial cover affects the concentration of gold nanoparticles in the ascending gas. This phenomenon may plausibly be used in exploration for concealed gold, copper–gold, and silver–gold deposits in areas of thick alluvial cover. Geofluids (2010) 10 , 438–446  相似文献   

10.
The geomorphological evolution of the upper Chienti river basin, during the late Pleistocene and the Holocene, was characterized mainly by numerous landslides, strongly affecting the river dynamics, that produced falls, deviations and in some cases total obstructions with the formation of lakes sometimes extending for some kilometres. Moreover, particularly during the Holocene, phytoclastic and phytohermal travertine deposits were deposited in correspondence of steps along the river bed; one of these deposits, by means of radiocarbon dating, has been dated between 8260 ± 100 yr BP and 7740 ± 80 yr BP. Stromatolithic travertine is also present at the base of Holocene channels, slightly incised on the top of the upper Pleistocene alluvial plain.  相似文献   

11.
The pre-Magdalenian phase of the Côa River Valley open-air rock art is mostly distributed at the boundary between the rocky valley slopes and the floodplain that correspond to the most favourable geomorphological setting for the preservation of pecked and deeply superposed engravings of the most famous artistic phase of the area. The natural vertical panels of the engraved art located at this geomorphological interface have suffered weathering during two cold events of the Lateglacial. They were buried by several colluvial and alluvial deposits. The reconstruction of the sedimentary and archaeological context of the CôaRiver Valley engraving permits a better assessment of the preservation processes and interpretation of Palaeolithic open-air rock art.  相似文献   

12.
Radiocarbon (14C) dates are the most important means for determining the age of Holocene archaeological deposits. The theoretical physical basis of this method is by now unassailable, having been consistently tested and refined over two generations. However, the means by which this method has been applied and the interpretation of these results remain as key issues, particularly for complex archaeological discoveries that substantially affect our understanding of world prehistory and social evolution. Many factors can produce uncertainty or variation in the 14C concentrations of samples, even those that have been selected from the same archaeological context or event. A number of recent studies have also addressed the ways in which ambiguities and irregularities in the 14C calibration curve can affect the interpretation of archaeological dates and temporal patterns. Of greatest concern, however, is a growing practice of using only one or two samples to date a significant prehistoric context or event. The date of these events, usually relative to other human activities, often holds important theoretical implications for evolutionary anthropology and related disciplines. In this article, we demonstrate that such a practice is rarely adequate or acceptable. Rather, proper procedure requires a suite of dates that permit statistical verification that the deposit or event itself is being correctly dated. We present a detailed case study that highlights the importance of analyzing multiple samples of 14C from significant archaeological contexts.  相似文献   

13.
The Terramara Santa Rosa is a Middle and Late Bronze Age archaeological site located in the Po alluvial plain, northern Italy. It is constituted of two moated villages delimited by earthen ramparts. The peripheral structures of the site are sealed by fine-textured flood plain deposits and they have not been fully explored through excavation due to their large extent. Because the shape of the villages and their relation to moats and the fluvial network are of paramount importance to understanding the landscape management and the use of water resources in the Terramare civilisation, a geophysical survey was planned to extend the results of the existing archaeological excavations to the site scale. A frequency-domain electro-magnetic sounding (FDEM) and electrical resistivity imaging (ERI) covered an area of approximately 26 ha; ERI was conducted for a total length >9000 m. Despite the predominance of electrically conductive fine-textured sediments, electrical resistivity anomalies were observed and they were attributed to subtle lithological differences in the sedimentary context of the alluvial plain. The geophysical interpretation, after the calibration with the excavation data, revealed the structures of the Terramara and of the surrounding hydraulic network, which are not visible at the surface due to flood plain deposits. The Santa Rosa site was founded in a favourable geomorphological position, on the top of a crevasse splay lobe of the adjoining Po palaeo-channel, rising above the surrounding alluvial plain. The Terramara and their surroundings were delineated through an artificial modification of this pre-existing crevasse splay lobe and a well-targeted urban design, with the objective of diverting water, most likely from a palaeo-channel of the Po River, through the digging of peripheral moats used to collect water around the site and to distribute it to the surrounding fields for irrigation. The water management documented by this study in the Terramara Santa Rosa can be considered as paradigmatic for the whole Terramare civilisation, which is therefore responsible of the introduction of the irrigated agriculture into western Europe for the first time.  相似文献   

14.
Mineral deposits in the Cupp‐Coutunn/Promeszutochnaya cave system (Turkmenia, central Asia) record a phase of hydrothermal activity within a pre‐existing karstic groundwater conduit system. Hydrothermal fluids entered the caves through fault zones and deposited sulphate, sulphide and carbonate minerals under phreatic conditions. Locally, intense alteration of limestone wall rocks also occurred at this stage. Elsewhere in the region, similar faults contain economic quantities of galena and elemental sulphur mineralization. Comparisons between the Pb and S isotope compositions of minerals found in cave and ore deposits confirm the link between economic mineralization and hydrothermal activity at Cupp‐Coutunn. The predominance of sulphate mineralization in Cupp‐Coutunn implies that the fluids were more oxidized in the higher permeability zone associated with the karst aquifer. A slight increase in the δ34S of sulphate minerals and a corresponding δ34S decrease in sulphides suggest that partial isotopic equilibration occurred during oxidation. Carbonate minerals indicate that the hydrothermal fluid was enriched in 18O (δ18OSMOW ~ + 10‰) relative to meteoric groundwater and seawater. Estimated values for δ13CDIC (δ13CPDB ~ ? 13‰) are consistent with compositions expected for dissolved inorganic carbon (DIC) derived from the products of thermal decomposition of organic matter and dissolution of marine carbonate. Values derived for δ13CDIC and δ18Owater indicate that the hydrothermal fluid was of basinal brine origin, generated by extensive water–rock interaction. Following the hydrothermal phase, speleothemic minerals were precipitated under vadose conditions. Speleothemic sulphates show a bimodal sulphur isotope distribution. One group has compositions similar to the hydrothermal sulphates, whilst the second group is characterized by higher δ34S values. This latter group may either record the effects of microbial sulphate reduction, or reflect the introduction of sulphate‐rich groundwater generated by the dissolution of overlying evaporites. Oxygen isotope compositions show that calcite speleothems were precipitated from nonthermal groundwater of meteoric origin. Carbonate speleothems are relatively enriched in 13C compared to most cave deposits, but can be explained by normal speleothem‐forming processes under thin, arid‐zone soils dominated by C4 vegetation. However, the presence of sulphate speleothems, with isotopic compositions indicative of the oxidation of hydrothermal sulphide, implies that CO2 derived by reaction of limestone with sulphuric acid (‘condensation corrosion’) contributed to the formation of 13C‐enriched speleothem deposits.  相似文献   

15.
A fossil mandible and incisor of the diprotodontid marsupial Palorchestes azeal Owen is reported from a new locality at Pulbeena, near Smithon, in northwestern Tasmania. The fossils occurred with a piece of wood which has a 14C age of 54,200-4,500 +11,000 B.P. Both fossils and wood were deposited contemporaneously in shallow-lake shell marls and swamp peat deposits of late Quaternary age. Pollen analysis indicates that this P. azael inhabited a Eucalyptus woodland.  相似文献   

16.
A long‐term pump test was conducted in the KTB pilot borehole (KTB‐VB), located in the Oberpfalz area, Germany. It produced 22 300 m3 of formation fluid. Initially, fluid production rate was 29 l min?1 for 4 months, but was then raised to an average of 57 l min?1 for eight more months. The aim of this study was to examine the fluid parameters and hydraulic properties of fractured, crystalline crusts as part of the new KTB programme ‘Energy and Fluid Transport in Continental Fault Systems’. KTB‐VB has an open‐hole section from 3850 to 4000 m depth that is in hydraulic contact with a prominent continental fault system in the area, called SE2. Salinity and temperature of the fluid inside the borehole, and consequently hydrostatic pressure, changed significantly throughout the test. Influence of these quantities on variations in fluid density had to be taken into account for interpretation of the pump test. Modelling of the pressure response related to the pumping was achieved assuming the validity of linear Darcy flow and permeability to be independent of the flow rate. Following the principle ‘minimum in model dimension’, we first examined whether the pressure response can be explained by an equivalent model where rock properties around the borehole are axially symmetric. Calculations show that the observed pressure data in KTB‐VB can in fact be reproduced through such a configuration. For the period of high pumping rate (57 l min?1) and the following recovery phase, the resulting parameters are 2.4 × 10?13 m3 in hydraulic transmissivity and 3.7 × 10?9 m Pa?1 in storativity for radial distances up to 187 m, and 4.7 × 10?14 m3 and 6.0 × 10?9 m Pa?1, respectively, for radial distances between 187 and 1200 m. The former pair of values mainly reflect the hydraulic properties of the fault zone SE2. For a more realistic hydraulic study on a greater scale, program FEFLOW was used. Parameter values were obtained by matching the calculated induced pressure signal to fluid‐level variations observed in the KTB main hole (KTB‐HB) located at 200 m radial distance from KTB‐VB. KTB‐HB is uncased from 9031 to 9100 m and shows indications of leakage in the casing at depths 5200–5600 m. Analysis of the pressure record and hydraulic modelling suggest the existence of a weak hydraulic communication between the two boreholes, probably at depths around the leakage. Hydraulic modelling of a major slug‐test in KTB‐HB that was run during the pumping in KTB‐VB reveals the effective transmissivity of the connected formation to be 1 to 2 orders of magnitude lower than the one determined for the SE2 fault zone.  相似文献   

17.
Abstract

Environmental monitoring at the World Heritage Site of Bryggen in Bergen, Norway, has shown damaging settling rates caused by degradation of underlying archaeological deposits. Measurements of piezometric head, oxygen, and soil moisture content, as well as chemical analyses of water and soil samples are key elements of the environmental monitoring.

Groundwater monitoring and geochemical analyses reveal a complex and dynamic flow through the natural and anthropogenic stratigraphy. The preservation conditions within the organic archaeological deposits are strongly correlated with oxygen and soil moisture content, that are controlled by the groundwater flow conditions at the site. To quantify decay rates, it is thus essential to understand the wider hydrogeological context of the site. This paper presents recent advancements in quantifying decay rates in the saturated zone at Bryggen. The paper also shows that 3D geo-archaeological modelling can contribute to preservation management by visually combining results of geological, archaeological, geochemical, and hydrological investigations. This opens up for improved multidisciplinary understanding of preservation potential, thereby contributing to an improved protection of archaeological deposits in situ.  相似文献   

18.
Caesium-137 from fallout from nuclear weapons tests is adsorbed on fine sediments and becomes an effective tracer. It is hypothesised that within a drainage basin, sites undergoing little or no erosion accumulate 137 Cs in their upper layers; cultivated soils will have 137 Cs uniformly distributed within the cultivated layer; eroded soils, cultivated or not, will have relatively less l37 Cs, depending on the severity of erosion. Accumulated sediments will have characteristic 137 Cs profiles reflecting temporal fallout variations and sedimentation history. This hypothetical model is largely confirmed by results from Maluna Creek basin, where erosion and accumulation of sediments has taken place. Soils under viticulture have about one third the 137 Cs content of soils with grass cover, indicating more severe erosion under cultivation. Caesium-137 profiles in alluvial fan and flood plain deposits correlate with sediment layers and known cultivation history.  相似文献   

19.
Antlers and bones of reindeer (Rangifer tarandus L.) are the most frequently found vertebrate remains from the Late Glacial deposits of Southern Scandinavia. The Danish collection now consists of more than 350 specimens and of these 47 have been radiocarbon dated extending the range of occurrence in the area with ca. 1300 14C yr. Thus the first occurrence is pushed back to ca. 12?500 14C yr BP (late Bølling chronozone) while the youngest date lies at ca. 9200 14C yr BP (late Preboreal chronozone) establishing that the reindeer survives well into the Holocene. The seasonal dates of the reindeer indicate for the first human occupation (the Havelte group from the Bølling period) a summer, autumn and early winter occupation, with reindeer, as well as man, apparently being absent during the coldest winter months. Finally, it is shown that Southern Scandinavia acted as a calving area throughout the Late Glacial and Early Holocene thus discrediting the North–South model of reindeer groups moving from a wintering area in Southern Scandinavia to a calving area in the foothills of the North European plain.  相似文献   

20.
P. W. Cromie  Khin Zaw 《Geofluids》2003,3(2):133-143
Carlin‐type gold deposits in southern China are present in Palaeozoic to Mesozoic siliciclastic and carbonate rocks. The border region of Yunnan, Guizhou and Guangxi Provinces contains gold deposits on the south‐western margin of the Pre‐Cambrian South China Craton in south‐eastern Yunnan Province. The Fu Ning gold deposits host epigenetic, micron‐sized disseminated gold in: (i) Middle Devonian (D1p) black carbonaceous mudstone at the Kuzhubao gold deposit and (ii) fault breccia zones at the contact between Triassic gabbro (β ) and the Devonian mudstone (D1p) at the Bashishan gold deposit. The deposits are associated with zones of intense deformation with enhanced permeability and porosity that focused hydrothermal fluid flow, especially where low‐angle N‐S striking thrust faults are cut by NW striking strike‐slip and/or NE striking normal faults. Major sulphide ore minerals in the Fu Ning gold deposits are pyrite, arsenopyrite, arsenic‐rich pyrite, stibnite and minor iron‐poor sphalerite. Gangue minerals are quartz, sericite, calcite, ankerite and chlorite. Hypogene ore grades range from 1 to 7 g t?1 Au and up to 18 g t?1 Au at the Kuzhubao gold deposit and are generally less than 3 g t?1 Au at the Bashishan gold deposit. Sub‐microscopic gold mineralization is associated with finely disseminated arsenic‐rich pyrite in the Stage III mineral assemblage. Two types of primary fluid inclusions have been recorded: Type I liquid–vapour inclusions with moderate‐to‐high liquid/vapour ratios, and Type II inclusions containing moderate liquid/vapour ratios with CO2 as determined from laser Raman analysis. Temperature of homogenization (Th) data collected from these primary fluid inclusions in gold‐ore Stage III quartz ranged from 180 to 275°C at the Kuzhubao gold deposit and 210 to 330°C at the Bashishan gold deposit. Salinity results indicate that there were possibly two fluids present during gold deposition, including: (i) an early fluid with 0.8–6.5 wt.% NaCl equivalent, similar to salinity in shear‐zone‐hosted gold deposits with metamorphic derived fluids; and (ii) a late fluid with 11.8–13.4 wt.% NaCl equivalent, indicating possible derivation from connate waters and/or brine sources. CO2 and trace CH4 were only detected by laser Raman spectrometry in gold‐ore‐stage primary fluid inclusions. Results of sulphur isotope studies showed that δ34S values for pyrite and arsenopyrite associated with gold‐ore mineralization during Stage III at the Kuzhubao and Bashishan gold deposits are isotopically similar and moderately heavy with a range from +9 to +15 per mil, and also fall into the range of δ34S values reported for Carlin‐type gold deposits. Sulphur isotopes suggest that the Fu Ning gold deposits were formed from connate waters and/or basinal brines. Fluid geochemistry data from the Fu Ning gold deposits suggest a Carlin‐type genetic model, involving fluid mixing between: (i) deep CO2‐rich metamorphic fluids, (ii) moderately saline, reduced connate waters and/or basinal brines; and (iii) evolved meteoric waters.  相似文献   

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