Mapping the archaeological soil archive of sand and gravel mineral reserves in Britain

Primary sand and gravel deposits in Britain play an important role in preserving our cultural heritage and are also a valuable aggregate resource. While an understanding of the extrinsic properties of the soil archive (such as pH, redox, groundwater) can provide a firstorder assessment of the potential risk to any archaeologically sensitive deposits, we have very poor definition of spatial variations in the extrinsic properties of soil that influence archaeological preservation at a regional and national scale. Developments in digital geological mapping, remote sensing, and geochemical survey data undertaken by the British Geological Survey (BGS) have, however, significantly extended capabilities in this respect and can potentially be used to provide a primary assessment of the sensitivity of the present soil archive and the potential risk from changes to the soil process on cultural material in areas earmarked for aggregate extraction. Two of the major factors affecting archaeological preservation—soil acidification and groundwater—can be mapped or predicted at scales of better than 1:50,000 across increasingly large parts of the country using a combination of regional hydrogeological, geophysical, and geochemical data. Additional data from site investigations may further refine preservation potential as a function of changes in redox potential and acidity. These data, maps and models can be used to (1) better establish a baseline for archaeological preservation at a regional and national scale and (2) improve our understanding of how the physical and chemical properties of the near surface environment can be managed to sustainably preserve archaeological materials in areas impacted by sand and gravel extraction. © 2009 Wiley Periodicals, Inc.     

Weathered bedrock as a source of sand and gravel aggregate in north-eastern New South Wales, Australia

 The most commonly recognized sources of sand and gravel aggregate are the deposits of coastal, fluvial and glacial sedimentary processes. It is not commonly recognized that weathered bedrock is also an important source of sand and gravel aggregate. In the case of weathered sedimentary bedrock the product may be indistinguishable from modern sedimentary materials and deposits may be misidentified. Batson's quarry is a major sand and gravel aggregate resource for the rapidly developing region of north-eastern New South Wales. The deposit has previously been assumed to be a young sedimentary deposit, but detailed field examination and comparison with surrounding rock types indicates that it has formed from weathered Mesozoic sandstone bedrock. The extraction of weathered bedrock aggregate deposits has distinctive environmental implications because, unlike sedimentary aggregates, they are not restricted by the geometry of sedimentary environments and do not necessarily interfere with surface drainage systems. This study shows that the recognition of the geological origin of a resource is essential in order to determine its potential geographical extent, and thereby maximize its utilization and minimize land use conflict. Received: 3 January 1996 / Accepted: 1 November 1996     

Mapping the Pliocene Clay Deposits Using Remote Sensing and its Impact on the Urbanization Developments in Egypt: Case Study,East Sohag Area

In the current study, Thematic Mapper image was compiled along with field and laboratory investigation results to map the Pliocene clay deposits. These deposits have high swelling potential; consequently they will have a negative impact on the urbanization expansion surrounding the flood plain zone (Low desert zone) in Egypt. Principle Component and Minimum Noise Fraction techniques with the help of supervised classification were successful in the mapping of these deposits. The interpretation shows that the Pliocene clay deposits occupy most of the wadis terraces and part of the wadis floors, and sometimes they covered by Quaternary deposits (1–5 m of sand and gravel). The physio-chemical characteristics of these deposits indicate that the Pliocene clay ranges from silty clay to clay with small amounts of sand. Laboratory analysis (Atterberg limits, saturation degree, and cation exchange capacity) indicate the swelling characteristics of the Pliocene clay. Different classification systems were applied and all reveal the expansive nature of this soil, which should be taken into account for future development in the area.     

海南岛北部海域海砂资源潜力评价

海南岛北部浅海海砂资源丰富,以砂砾质沉积为主,集中于琼州海峡东口潮流沙脊区、河口三角洲和沿岸水下岸坡等海域。本文通过对海南岛北部海域的地形地貌、地层、底质类型等方面的调查,分东、西两个区域研究了海砂资源的分布、范围、规模和类型等地质特征,并估算了海砂资源量,结合沉积环境,评价了各区域海砂的资源潜力。研究区海砂分布广泛,但东、西区特征和规模具有较大差异,西区海砂以砂质砾和泥质砂为主,厚度5~10 m;东区海砂以砂、砾质砂和砂质砾为主,厚度10~50 m,规模远超西区。研究区共圈定出9处资源潜力区,资源量为91.4亿m³,其余区域为远景区,其资源量为71.5亿m³。根据地形地貌、水动力和沉积环境等因素,研究区海砂可分为潮流沙脊堆积体系、河口水下三角洲堆积体系、岬湾海岸水下岸坡堆积体系和侵蚀残留体系几种类型。其中位于琼州海峡东口浅滩区的潮流沙脊堆积体系海砂连续分布面积达328 km²,平均厚度超过25 m,资源量83.9亿m³,最具潜力。     

Geologically controlled bi-directional exchange of groundwater with a hypersaline lake in the Canadian prairies

Hypersaline lakes occur in hydrologically closed basins due to evaporitic enrichment of dissolved salts transported to the lakes by surface water and groundwater. At the hypersaline Lydden Lake in Saskatchewan, Canada, groundwater/lake-water interaction is strongly influenced by the geological heterogeneity of glacial deposits, whereby a highly permeable glaciofluvial sand/gravel deposit is underlain by glaciolacustrine deposits consisting of dense clay interspersed with silt/sand lenses. Pressure head distribution in a near shore area indicates a bi-directional flow system. It consists of topographically driven flow of fresh groundwater towards the lake in the sand/gravel aquifer and density-driven, landward flow of saline groundwater in the underlying glaciolacustrine deposits. Electrical resistivity tomography, and chemical and isotopic composition of groundwater clearly show the landward intrusion of saline water in the heterogeneous unit. The feasibility of bi-directional flow and transport is supported by numerical simulations of density-coupled groundwater flow and transport. The results suggest that the geologically controlled groundwater exchange processes have substantial influences on both inputs and outputs of dissolved minerals in hypersaline lakes in closed basins.     

Karst subsidence as a control on the accumulation and preservation of aeolian deposits: A Pleistocene example from a proglacial outwash setting,Ebro Basin,Spain

Meltwater flows emanating from the Pyrenees during the Pleistocene constructed a braided outwash plain in the Ebro Basin and led to the karstification of the Neogene gypsum bedrock. Synsedimentary evaporite dissolution locally increased subsidence rates and generated dolines and collapses that enabled the accumulation and preservation of outwash gravels and associated windblown deposits that were protected from erosion by later meltwater flows. In these localized depocentres, maximum rates of wind deceleration resulted from airflow expansion, enabling the accumulation of cross‐stratified sets of aeolian strata climbing at steep angles and thereby preserving up to 5 m thick sets. The outwash plain was characterized by longitudinal and transverse fluvial gravel bars, channels and windblown facies organized into aeolian sand sheets, transverse and complex aeolian dunes, and loess accumulations. Flat‐lying aeolian deposits merge laterally to partly deformed aeolian deposits encased in dolines and collapses. Synsedimentary evaporite dissolution caused gravels and aeolian sand deposits to subside, such that formerly near‐horizontal strata became inclined and generated multiple internal angular unconformities. During episodes when the wind was undersaturated with respect to its potential sand transporting capacity, deflation occurred over the outwash plain and coarse‐grained lags with ventifacts developed. Subsequent high‐energy flows episodically reached the aeolian dune field, leading to dune destruction and the generation of hyperconcentrated flow deposits composed in part of reworked aeolian sands. Lacustrine deposits in the distal part of the outwash plain preserve rhythmically laminated lutites and associated Gilbert‐type gravel deltas, which developed when fluvial streams reached proglacial lakes. This study documents the first evidence of an extensive Pleistocene proglacial aeolian dune field located in the Ebro Basin (41˙50° N), south of what has hitherto been considered to be the southern boundary of Pleistocene aeolian deposits in Europe. A non‐conventional mechanism (evaporite karst‐related subsidence) for the preservation of aeolian sands in the stratigraphic record is proposed.     

Arsenic toxicity of groundwater in parts of the Bengal basin in India and Bangladesh: the role of Quaternary stratigraphy and Holocene sea-level fluctuation

 Arsenic toxicity in groundwater in the Ganges delta and some low-lying areas in the Bengal basin is confined to middle Holocene sediments. Dissected terraces and highlands of Pleistocene and early Holocene deposits are free of such problems. Arsenic-rich pyrite or other arsenic minerals are rare or absent in the affected sediments. Arsenic appears to occur adsorbed on iron hydroxide-coated sand grains and clay minerals and is transported in soluble form and co-precipitated with, or is scavenged by, Fe(III) and Mn(IV) in the sediments. It became preferentially entrapped in fine-grained and organic-rich sediments during mid-Holocene sea-level rises in deltaic and some low-lying areas of the Bengal basin. It was liberated subsequently under reducing conditions and mediated further by microbial action. Intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater. This practice has induced groundwater flow, mobilizing phosphate derived from fertilizer, as well as from decayed organic matter, which has promoted the growth of sediment biota and aided the further release of arsenic. However, the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the Ganges floodplains upstream of Rajmahal. Thus, arsenic toxicity in the groundwater of the Bengal basin is caused by its natural setting, but also appears to be triggered by recent anthropogenic activities. Received: 23 August 1999 · Accepted: 16 November 1999     

海河流域地下水资源保护

地下水资源在海河流域至关重要的资源。海河平原的浅层和深层含水层大面积处于严重超采状态。地下水资源的的过量开采造成了严重环境问题。为了保护地下水资源，评价了可行的技术。利用洪水和废水进行人工回灌已进行了试验。在很多地区可以应用地表回灌系统，城市地区实施深层含水层的回灌。更好地策略是减少地下水的抽取量，特别是为了减缓地面沉降和海水入侵。应该联合运用减少地下水抽水量和人工回灌，以解决地下水位持续下降和含水层恢复的问题。     

Using a Particle Tracking Method to Quantify Groundwater Circulation rates: a Case Study in the Ordos Plateau

Groundwater is a valuable resource in many areas, and commonly plays a key role in economic development. Therefore, groundwater circulation rates at different depths are key issues for groundwater development and management in the Ordos Plateau. In this study, a particle tracking method was used to quantify circulation rates in the Ordos plateau. The results show that groundwater mainly circulates in shallow groundwater systems up to 400m depth. The results of this study can be used to develop effective programs for groundwater management and development     

Mineral resources for a new town

Of all the materials required for construction of a new town, the only one that must be obtained locally is aggregate for concrete. Very large tonnages of sand and gravel, or crushed stone, will be needed. Their production must be planned for from the beginning, to avoid the conflicts in land use that have long plagued older communities that undergo expansion. Production of sand, gravel, and stone is now disallowed by zoning in most major urban corridors in the U.S.A., making it necessary to bring these materials from a distance, at higher costs than formerly. Yet some success has been achieved in fitting the aggregates industry into the urban picture. Two examples are cited, involving production of stone in New Jersey and gravel in southern California. Where planning is done from the start, areas of occurrence of sand, gravel, or good-quality stone must be set aside for extractive industry. It is the geologiest's responsibility to provide information on locality of occurrence, tonnage present, thickness of overburden, best way to exploit the deposit with minimum environmental effect, and feasible use of the area after it has been worked out. The possibility of obtaining stone from below ground should also be evaluated. Only by such advance planning, with geological input, can conflicts in land use and excessive cost of construction aggregate be avoided.     

Geomorphological evidence from the Lleyn Peninsula constraining models of the magnitude and rate of isostatic rebound during deglaciation of the Irish Sea Basin

A stepped series of sand and gravel terraces on the Lleyn peninsula of North Wales is used to test the magnitude and rate of isostatic depression required by the recently proposed glacimarine model of deglaciation of the Irish Sea Basin. A relative sea-level fall of 70 m is required while the ice remained pinned at the north Lleyn coast. Even taking the maximum known rate of isostatic uplift, the margin would have to remain stationary for 1400 years. It seems more reasonable to interpret the Lleyn terraces, and similar features around the Irish Sea Basin, as glacifluvial and glacilacustrine.     

Confined groundwater system in Tokyo

The Musashino Terrace and the Shitamachi Lowland, the main urban areas in the Tokyo metropolis, are in the eastern part of Tokyo and are underlain by thick Quaternary sediments. The geologic structrue of these sediments has a general strike of WNW—ESE, with a gentle dip to the east in the western part of the Musashino Terrace, and strikes generally to the E—W with a gentle dip to the north in the eastern part of the terrace and strikes WNW—ESE to N—S with a very gentle dip to the east in the Shitamachi Lowland. The basal sediments in this area consist chiefly of massive thick silty layers, whereas the sediments overlying them consist of alternating layers of silt, sand, and gravel, which act as confined aquifers throughout the Musashino Terrace and the Shitamachi Lowland. Confined groundwater systems are being developed in the Tama District, the western part of the terrace, and are mainly recharged with river water from the Tama River. The unconfined groundwater system is being developed in the surface layers such as terrace sand and gravel formations and the Kanto Loam Formation. These confined aquifers that are being developed throughout the terrace and the lowland have been exploited for household water supplies and industrial and air-conditioning use for nearly seven decades. The heavy utilization of the confined groundwater, however, has caused a major lowering of groundwater levels. As a result of the lowering of groundwater levels, land subsidence has occurred all over the Lowland and the terrace. At this time the national government and the Tokyo Metropolitan Government restricted groundwater withdrawals for industrial, air-conditioning use and the others except for household supply. Owing to these restrictions, not only have the water levels recovered, but land subsidence has rapidly declined since around 1973.     

Hyperpycnal delivery of sand to the continental shelf: Insights from the Jurassic Lajas Formation,Neuquén Basin,Argentina

Hyperpycnal currents are river‐derived turbidity currents capable of transporting significant volumes of sediment from the shoreline onto the shelf and potentially further to deep ocean basins. However, their capacity to deposit sand bodies on the continental shelf is poorly understood. Shelf hyperpycnites remain an overlooked depositional element in source to sink systems, primarily due to their limited recognition in the rock record. Recent discoveries of modern shelf hyperpycnites, and previous work describing hyperpycnites deposited in slope or deep‐water settings, provide a valuable framework for understanding and recognizing shelf hyperpycnites in the rock record. This article describes well‐sorted lobate sand bodies on the continental shelf of the Neuquén Basin, Argentina, interpreted to have been deposited by hyperpycnal currents. These hyperpycnites of the Jurassic Lajas Formation are characterized by well‐sorted, medium‐grained, parallel‐laminated sandstones with hundreds of metre extensive, decimetre thick beds encased by organic‐rich, thinly laminated sandstone and siltstone. These deposits represent slightly obliquely‐migrating sand lobes fed by small rivers and deposited on the continental shelf. Hyperpycnites of the Lajas Formation highlight several unique characteristics of hyperpycnal deposits, including their distinctively thick horizontal laminae attributed to pulsing of the hyperpycnal currents, the extraction of coarse gravel due to low flow competence, and the extraction of mud due to lofting of light interstitial fluid. Recognition of shelf hyperpycnites in the Lajas Formation of the Neuquén Basin allows for a broader understanding of shelf processes and adds to the developing facies models of hyperpycnites. Recognizing and understanding the geometry and internal architecture of shelf hyperpycnites will improve current understanding of sediment transfer from rivers to deeper water, will improve palaeoenvironmental interpretations of sediment gravity‐flow deposits, and has implications for modelling potentially high‐quality hydrocarbon reservoirs.     

Hydrogeophysical investigations for assessing the groundwater potential in part of the Peshawar basin,Pakistan

A large number of valleys and basin systems are present in the northwestern part of the Himalayas in Pakistan which form significant aquifers in the region. Hydrogeophysical investigations in the western part of Nowshera District, a part of the intermontane Peshawar basin, were undertaken to help to determine the availability of groundwater resources in the region. Thirty vertical electrical resistivity soundings (VES) were acquired using a Schlumberger expanding array configuration with a maximum current electrode spacing (AB/2) of 150 m in delineating the groundwater potential in the study area. The results of the interpreted VES data using a combination of curve matching technique and computer iterative modeling methods suggest that the area is underlain by 3 to 5 geo-electric layers. The interpretation results showed that the geo-electrical succession consists of alluvium comprising of alternating layers of clay, silty clay, fine to coarse sands, sand with gravels and gravels of variable thickness. High subsurface resistivity values are correlated with gravel–sand units and low resistivity values with the presence of clays and silts. The modeled VES results were correlated with the pumping tests results and lithological logs of the existing wells. The pumping test suggests the transmissivity of the aquifer sediments is variable corresponding to different sediments within the area. The gravel–sand intervals having high resistivity value show high transmissivity values, whereas clay–silt sediments show low transmissivities. It is concluded that majority of the high resistive gravel–sand sediments belong to an alluvial fan environment. These gravel–sand zones are promising zones for groundwater abstraction which are concentrated in the central part of the study area.     

张掖城市湿地地下水防污性评价研究

通过系统分析张掖城市湿地水文地质条件,采用DRASTIC法,选取了地下水位埋深、净补给量、含水层介质、土壤介质、地形、包气带介质和渗透系数共七项影响因子对张掖城市湿地城市区地下水防污性进行了评价。结果表明,张掖城市湿地地下水防污性较好地带主要分布在研究区南部新墩镇——二十里铺一带地下水深埋区,水位埋深一般大于10 m,...     

Groundwater resources protection and aquifer recovery in China

The groundwater resources in China and especially the northern part represent a vital water resource. Both the shallow and deep aquifers are highly overexploited in a large area of north China. The heavy overexploitation of groundwater resources is causing major environmental damage. To protect groundwater resources, several technical feasibility studies were performed. Artificial recharge using floodwater and wastewater was tried. Surface spreading systems are applicable in many areas of the Yellow River basin and Hai River basin. Deep aquifer injections were undertaken in the urban area. A far better strategy is to reduce the extraction of groundwater, especially to stop or slow down land subsidence and seawater intrusion. To address the problem of falling groundwater levels and aquifer recovery, there is a need reduce groundwater extraction and artificial recharge.     

Bed forms and stratification types of modern gravel meander lobes, Nueces River, Texas

All major streams draining the southwestern flank of the Edwards Plateau in south-central Texas transport large volumes of gravel and sandy muddy gravel and are developing meander lobe sequences consisting predominantly of coarse gravel. The largest of these streams, the Nueces River, has a sinuosity index of 1.3 and an average stream surface slope of 1.8 m/km in the study area. Stream discharge is variable and has ranged from no flow to more than 17,000 m³/s. Mean clast b-axis length for the ten largest clasts at thirteen sample sites ranged from 2.5 to 10.8 cm. Velocities of 2.7-4.4 m/s 1 m above the stream bed are required to transport these clasts. Stream velocities of these magnitudes occur about once in 8 years when discharge of the Nueces River exceeds 3300 m³/s. Mean grain size of Nueces River alluvium ranges from 1.2 to 3.4 cm. At a flow depth of 1 m, sediment of this size has a critical erosion velocity of 1.8-3 m/s. Velocities of this magnitude occur about once in two years when discharge exceeds 340 m³/s. Under these conditions flow is subcritical, with critical shear stresses on depositional surfaces ranging from 6.4 to 12.7 kg/m². Gravel clasts are imbricated and channel bed forms are predominantly transverse gravel bars with slip faces ranging up to 2 m high and wavelengths in excess of 100 m. Stratification includes graded planar crossbeds and horizontal beds. Lower lateral accretion face sediments are also predominantly transverse bars; upper lateral accretion face deposits occur as longitudinal gravel ridges deposited in the lee of vegetation and, less commonly, as chute bars. Near the upper limit of meander lobes where vegetation is heavy, mud and muddy sand occur as overbank deposits; in these deposits sedimentary structures other than desiccation cracks are rare. Sedimentary sequences in gravel meander lobe systems deposited by low sinuosity streams are graded or non-graded horizontal beds and planar cross-beds overlain by mud and muddy sand interbedded with horizontally bedded gravels. Sequences may be several metres thick, but probably do not exceed 8-10 m in thickness. These deposits in turn are overlain by overbank deposits of mud and muddy sand. Similar sedimentary sequences occur in the extensive Quaternary terraces that parallel the Nueces River.     

A gravel lobe deposit in the prodelta of the Doumsan fan delta (Miocene), SE Korea

The Doumsan fan-delta system in the Pohang Basin (Miocene), SE Korea comprises tripartite components of Gilbert-type topset, foreset, and bottomset environments with an extended prodelta in the deeper part (a few hundred metres deep). The present study documents sedimentologic features and origin of a gravel body (here interpreted as a gravel lobe) formed in the prodelta region of the Doumsan fan delta. The gravel lobe lies on sandy mud deposits and is capped by a thick massive sand bed. It extends for more than 1.5 km with a height of up to 30 m and shows a narrow tongue-like geometry. Eight sedimentary facies have been distinguished to describe characteristic features of the gravel lobe and the associated deposits. Of these, three types of gravelly sedimentary facies are important with regard to volumetric contribution and depositional processes: (1) crudely stratified pebble-grade conglomerate; (2) disorganized, clast-rich pebble(-to-cobble)-grade conglomerate; and (3) matrix-rich, bimodal cobble-grade conglomerate. The former two types dominate the central part of the lobe where they are not accompanied by sand beds, whereas the latter, as subordinate units, is prevalent in the fringe which otherwise is dominated by thick sandy mud deposits. The stacked successions of crudely stratified pebble-grade conglomerate are representative of the active aggradational phases of the gravel lobe, whereas the occurrence of channels within the lobe reflects that the gravel lobe prograded under the influence of subaqueous channel systems. The gravel lobe resulted from catastrophic disturbance (slumping) on the foreset region that further caused the development of channel systems, promoting efficient transport of gravelly sediments. This type of deposit may represent an important additional category of low-efficiency subaqueous fans.     

Groundwater quality of porous aquifers in Greece: a synoptic review

Greece is dependent on groundwater resources for its water supply. The main aquifers are within carbonate rocks (karstic aquifers) and coarse grained Neogene and Quaternary deposits (porous aquifers). The use of groundwater resources has become particularly intensive in coastal areas during the last decades with the intense urbanization, tourist development and irrigated land expansion. Sources of groundwater pollution are the seawater intrusion due to over-exploitation of coastal aquifers, the fertilizers from agricultural activities and the disposal of untreated wastewater in torrents or in old pumping wells. In the last decades the total abstractions from coastal aquifers exceed the natural recharge; so the aquifer systems are not used safely. Over-exploitation causes a negative water balance, triggering seawater intrusion. Seawater intrusion phenomena are recorded in coastal aquifer systems. Nitrate pollution is the second major source of groundwater degradation in many areas in Greece. The high levels of nitrate are probably the result of over-fertilization and the lack of sewage systems in some urban areas.     

基于GMS软件的海砂矿体三维地质建模和资源量估算

本文以南海北部某海域海砂矿区为例,提出了基于GMS软件的海砂矿三维地质建模和资源量估算方法.以钻孔和综合物探数据为源数据,划定了矿区内V1和V2矿体的边界,基于GMS软件系统构建了数据库,综合利用钻孔、综合物探、剖面图和海底地形控制面等资料,建立了三维地质模型,有效实现了海砂矿体三维可视化和体积资源量的估算.三维地质模...