A study on geology,geomorphology, hydrology,groundwater, and physical resources of the desertified Badia environment in Jordan towards sustainable development

This paper summarizes information on geomorphology and physical resources as a part of the Jordan Badia Research and Development Program. The research focused on the issue of the environment in arid lands as an aid to providing practical options for sustainable development, for the benefit not only of the Hashemite Kingdom of Jordan but of other arid regions of the world. The research is significant in that there is a need to identify usable natural resources and establish a framework for their effective exploitation and management in a marginal, fragile environment, which is sensitive to change. Pressure for development of the Badia stems from the fact that the great majority of the population in Jordan is compressed into less than 10% of the country by environmental constraints. It is hoped that the Jordan Badia Research and Development Program will provide the required framework to ease current environmental pressures, encourage migration to the Badia, a sparsely populated region, and establish economically and ecologically self-supporting communities. This paper discusses the following areas that are related to the sustainable development of the Jordan Badia with special emphasis on the Safawi area in the northern Jordan Badia; geomorphology, including landform, processes, and hazards; geology and physical resources; hydrology; surface water and water engineering; and groundwater.     

Interglacial high‐tide coasts in the Bristol Channel and Severn Estuary,southwest Britain: a comparison for the Ipswichian and Holocene

The Ipswichian high‐tide coast in the Bristol Channel and Severn Estuary at the time of the highest sea‐levels (5–10 m OD) was wave‐dominated almost everywhere. It is defined by raised beaches and inshore sand shoals, and only in comparatively long but narrow inlets (Somerset Levels) are estuarine conditions evident. The modern Holocene seaway is wave‐dominated at high tide only up to and including the inner Bristol Channel. A muddy upper shore typifies the large, tide‐dominated Severn Estuary to the east and northeast. The larger depth and width of the Ipswichian seaway may explain its greater wave‐dominance, but it is also possible that differences in the sediment regime also contribute to the contrast observed. With water levels continuing to rise, the Holocene seaway could reach Ipswichian depths within a few thousand years and evolve toward greater wave‐dominance. A secondary effect may be the transgression and substantial removal of the Holocene estuarine sequence associated with the Severn Estuary Levels. Copyright © 2002 John Wiley & Sons, Ltd.     

Dynamics and palaeoclimatic significance of a Loch Lomond Stadial glacier: Coire Ardair,Creag Meagaidh,Western Highlands,Scotland

The extent, basal conditions and retreat history of a Loch Lomond Stadial glacier are reconstructed based on detailed geomorphological and sedimentological assessment. We present new evidence from the vicinity of Coire Ardair that supports the former existence of a warm-based, locally-fed valley glacier, with probable cold-based ice on the surrounding plateau. This is broadly consistent with modelled creep-dominated flow in the upper catchment and sliding-dominated flow throughout much of the valley. A dense suite of moraines, primarily formed in ice-marginal environments, records a multi-phase recessional history: (1) active and oscillatory retreat; (2) a prolonged ice stillstand; (3) partial ice stagnation with occasional minor readvances; (4) increased oscillatory retreat with a substantial readvance event; and (5) rapid and uninterrupted retreat. We propose that a Coire Ardair glacier responded to sub-centennial scale climate fluctuations, possibly associated with the periodic delivery of warmer air masses to the region, rather than to a single, prominent shift in climate.     

Large‐scale structures on Gazelle Peninsula,New Britain: Implications for the evolution of the New Britain arc

Geological mapping of fault systems on the Gazelle Peninsula, eastern New Britain arc, combined with a reinterpretation of existing sea floor data indicate that faults previously thought to be a possible location of the boundary between the North and South Bismarck Plates, do not appear to be directly related to the plate boundary spreading centres and transform faults in the 3.5 Ma Manus Basin. Structure on the Gazelle Peninsula is dominated by the Mediva Fault (new name) and the Wide Bay Fault System, both north‐northwest trending, deep‐seated features. The Mediva Fault, an element of the Baining Mountain Horst and Graben Zone, is an extensional structure which has focused Middle Miocene intrusive activity, controlled Mio‐Pliocene sedimentation in the central Gazelle Peninsula, and displaced Quaternary volcanic deposits. The Wide Bay Fault System has been active since at least the Late Oligocene. One hundred kilometres of sinistral strike‐slip motion is likely on this fault since at least the late Middle Miocene, moving the Gazelle Peninsula in a north‐northwest direction with respect to the remainder of New Britain. The nature and timing of movements along these two major structures indicate that some other major tectonic process has operated (and presently continues) in this region of the New Britain arc to create these structures.     

喀斯特生态系统生物地球化学过程与物质循环研究:重要性、现状与趋势

喀斯特地质与生态系统是地球表层系统中的重要组成部分,其变化将对其他地区以及整个地球系统产生影响.生物地球化学循环是全球和区域变化研究的核心内容,而生态系统的演化与系统内水分和养分的生物地球化学循环密切相关。因此,我们有必要将喀斯特生态系统纳入到更大区域或全球生态系统中进行分析研究,在充分研究认识整个喀斯特生态系统物质生物地球化学循环规律的基础上,进一步研究喀斯特生态系统的全球变化响应或影响机制,为喀斯特生态系统优化调控对策和措施提供科学基础。研究生态系统演化过程中物质的生物地球化学循环规律,是研究植物适生性、物种优化配置和适应性生态系统调控机理的关键基础。在介绍前人工作基础的同时,本文全面而概括地总结了我们近年利用元素、同位素(如δ13C、δ15N、δ34S、87Sr/86Sr)示踪和化学计量学理论和方法对喀斯特生态系统中不同界面和流域中物质的生物地球化学循环及其生态环境效应的研究成果。认识到:喀斯特流域生物地球化学循环活跃,相互耦合,并与流域生态环境变化相互制约;人类活动正干预流域物质的自然生物地球化学循环过程,并导致相应的生态和环境效应;全球变化科学深化有赖于区域生态环境变化及物质生物地球化学循环的研究。这些认识是我们将来系统深入开展喀斯特以及其他流域生态系统物质生物地球化学循环研究的重要方向。     

Geological and geochemical constraints on the Cheshmeh-Frezi volcanogenic stratiform manganese deposit,southwest Sabzevar basin,Iran

The Cheshmeh-Frezi Mn deposit belongs to the southwest Sabzevar basin to the north of the Central Iranian microcontinent. This basin, which hosts abundant mineral deposits including Mn exhalative and Besshi-type Cu-Zn volcanogenic massive sulfide deposits, followed an evolution closely related to the subduction of the Neo-Tethys oceanic crust beneath the Central Iranian microcontinent. Two major sedimentary sequences are recorded within this basin: (I) the Lower Late Cretaceous volcano-sedimentary sequence (LLCVSS) and (II) the Upper Late Cretaceous sedimentary dominated sequence (ULCSS). The Cheshmeh-Frezi Mn deposit is hosted within red tuff with interbeds of green tuffaceous sandstone of the LLCVSS. Mineralization occurs as stratiform blanket-like and tabular orebodies. Psilomelane, pyrolusite and braunite are the main minerals of the ore, which display a variety of textures. Such as layered, laminated, disseminated, massive, replacement or open space fillings. The footwall and hanging-wall volcanic rocks are predominantly andesite and trachyandesite rocks. Footwall and hangingwall volcanic rocks at Cheshmeh-Frezi are enriched in light rare earth elements (LREEs) compared to chondrite, have steep REE patterns, and generally show Ta and Nb depletions relative to chondrite which are characteristic of back-arc environments. The significant geochemical characteristics of ore such as high Mn content (12.41–33.14 wt%; average 19.41 wt%), low concentration of Fe (0.64–2.27 wt%; average 1.63 wt%), high Ba (49.7–9901 ppm, average 2728.67 ppm), LREE > HREE, and negative Ce and Eu anomalies reveal a primary distal hydrothermal-exhalative source for mineralization. Cheshmeh-Frezi deposit, in comparison with different types of volcanogenic manganese deposits shows broad similarities with the Cuban-type Mn deposits such as tectonic, host and associated rock types, geometry, textures, structures, mineralogy and lithogeochemistry.     

Bedrock, soils, and hillslope hydrology in the Central Texas Hill Country, USA: implications on environmental management in a carbonate-rock terrain

The Hill Country of Central Texas, USA, is undergoing rapid socioeconomic development, but environmental management of this region is hampered by misconceptions about local bedrock, soils, terrain, and hydrologic processes. The Hill Country is underlain mostly by Glen Rose Limestone (Lower Cretaceous) and exhibits a stepped terrain, which has been incorrectly attributed to alternating hard and soft bedrock strata. Other characteristics mistakenly attributed to this landscape include thin soils with scant water-retention capabilities, and rapid runoff as the dominant hydrologic process. This report presents new findings: unweathered bedrock is well indurated, but interbeds exhibit variable weathering rates. Recessive slopes (“risers”) on this stepped terrain result from rapid deterioration of strata having generally heterogeneous depositional fabrics (bioturbation and irregular clay partings) in contrast to ledge-forming strata having homogeneous fabrics. A stony regolith is thus formed beneath risers, providing porous and permeable ground that retards runoff and promotes the formation of moderately deep to deep (two-tiered) regolith/soil zones. These surficial materials on local steep slopes compose important natural environmental buffers; they support diverse biota and enhanced geochemical cycling of nutrients; they also exhibit significant water retention and enhanced erosion abatement. Proper land management demands recognition of these attributes in the siting, design, and construction of facilities.     

Periglacial trimlines and nunataks of the Last Glacial Maximum: the Gap of Dunloe,southwest Ireland

During the last main phase of glaciation (26–13 ka) an ice‐cap developed in southwest Ireland and ice, from a dispersal centre in the vicinity of Kenmare, flowed north through the Gap of Dunloe in the Macgillycuddy's Reeks. On surrounding hillsides a weathering limit separates ice‐moulded bedrock, on low ground, from frost‐weathered terrain above. Assessment of bedrock dilation joint characteristics, Schmidt hammer R‐value data and clay‐sized mineral contents of basal soil samples, demonstrate significant contrasts in the degree of weathering above and below this limit. The weathering limit declines in altitude along former ice flow‐lines and is confluent with morainic deposits on the eastern side of the Gap. This supports the assertion that the high‐level weathering limit is a periglacial trimline that marks the former maximum upper limit of the body of ice which occupied the Gap of Dunloe during the Last Glacial Maximum (LGM). Reconstruction of the former ice‐surface profile from periglacial trimline limits on the eastern side of the Gap yields a mean estimate for basal shear stress of 106.5 kPa. This value suggests that the ice mass which occupied the Gap of Dunloe at the LGM was warm based and flowed on a bedrock substrate. Copyright © 2004 John Wiley & Sons, Ltd.     

Arsenic-contaminated groundwater from parts of Damodar fan-delta and west of Bhagirathi River,West Bengal,India: influence of fluvial geomorphology and Quaternary morphostratigraphy

Arsenic contamination in groundwater affecting West Bengal (India) and Bangladesh is a serious environmental problem. Contamination is extensive in the low-lying areas of Bhagirathi–Ganga delta, located mainly to the east of the Bhagirathi River. A few isolated As-contaminated areas occur west of the Bhagirathi River and over the lower parts of the Damodar river fan-delta. The Damodar being a Peninsular Indian river, the arsenic problem is not restricted to Himalayan rivers alone. Arsenic contamination in the Bengal Delta is confined to the Holocene Younger Delta Plain and the alluvium that was deposited around 10,000–7,000 years bp, under combined influence of the Holocene sea-level rise and rapid erosion in the Himalaya. Further, contaminated areas are often located close to distribution of abandoned or existing channels, swamps, which are areas of surface water and biomass accumulation. Extensive extraction of groundwater mainly from shallow aquifers cause recharge from nearby surface water bodies. Infiltration of recharge water enriched in dissolved organic matter derived either from recently accumulated biomass and/or from sediment organic matter enhanced reductive dissolution of hydrated iron oxide that are present mainly as sediment grain coatings in the aquifers enhancing release of sorbed arsenic to groundwater.     

Hydrogeologic-structure and groundwater-movement imaging in tideland using electrical sounding resistivity: a case study on the Ariake Sea coast, southwest Japan

Groundwater flow exerts a crucial control on the boundary between the sea and freshwater and is thus a key factor for preserving groundwater resources and preventing seawater intrusion in coastal areas. Although it is highly probable that geological faults in coastal areas affect groundwater flow patterns, the effect has not been described yet in detail. This study is aimed at detecting and imaging groundwater flow and its temporal change around a fault in a coastal area through resistivity and chargeability distributions using electrical sounding. The Okoshiki area in central Kyushu, southwest Japan, was selected as a case study area, because of the presence of Kamiouda Fault. The measurements were conducted along six lines of both parallel and perpendicular orientations to the coastline. A feature suggesting a fault zone was evident on two lines. Through the temporal change of resistivity, movement and mixing processes of the seawater and freshwater during the ebb, low and flood tides were interpreted. A conceptual model of the processes was constructed in which a fault zone and the configuration of bedrock are dominant elements by acting as a selective path and a barrier to the groundwater flow, respectively.     

Glacial geomorphology of Teesdale,northern Pennines,England: Implications for upland styles of ice stream operation and deglaciation in the British-Irish Ice Sheet

The glacial geomorphology of Teesdale and the North Pennines uplands is analysed in order to decipher: a) the operation of easterly flowing palaeo-ice streams in the British-Irish Ice Sheet; and b) the style of regional deglaciation. Six landform categories are: i) bedrock controlled features, including glacitectonic bedrock megablocks or ‘rubble moraine’; ii) discrete mounds and hills, often of unknown composition, interpreted as weakly streamlined moraines and potential ‘rubble moraine’; iii) non-streamlined drift mounds and ridges, representing lateral, frontal and inter-ice stream/interlobate moraines; iv) streamlined landforms, including drumlins of various elongation ratios and bedrock controlled lineations; v) glacifluvial outwash and depositional ridges; and vi) relict channels and valleys, related to glacial meltwater incision or meltwater re-occupation of preglacial fluvial features. Multiple tills in valley-floor drumlin exposures indicate that the subglacial bedform record is a blend of flow directions typical of areas of discontinuous till cover and extensive bedrock erosional landforms. Arcuate assemblages of partially streamlined drift mounds are likely to be glacially overridden latero-frontal moraines related to phases of “average glacial conditions” (palimpsests). Deglacial oscillations of a glacier lobe in mid-Teesdale are marked by five inset assemblages of moraines and associated drift and meltwater channels, named the Glacial Lake Eggleshope, Mill Hill, Gueswick, Hayberries and Lonton stages. The Lonton stage moraines are thought to be coeval with bedrock-cored moraines in the central Stainmore Gap and likely record the temporary development of cold-based or polythermal ice conditions around the margins of a plateau-based icefield during the Scottish Readvance.     

西南某水电站闸址区右岸泥石流特征及其工程效应研究

西南某水电站闸址区右岸三坪子沟,历史上曾多次发生泥石流活动。通过现场系统调查和室内的综合分析认为,该泥石流的特点如下:①地处扬子板块西缘(槽台结合部位),小流域主要出露浅变质的三叠系岩层,岩体经历多期强烈变形,具有复杂的构造背景;②小流域内见11条不同规模的断层,并发育多组节理,岩体破碎,有利于次生改造;③新构造活动强烈,第四纪以来抬升幅度大,多在2mm a以上;④降雨丰富,年降雨达1000mm以上,而且集中在6～9月份;⑤泥石流形成区汇水面积大,崩坡积及洪积物发育,物源丰富;⑥流通区窄陡,有利于泥石流的加速;⑦堆积区位于离沟口上游2km的古堰塞湖内;⑧由于沟口泥石流搬运的大部分固体物质未到沟口就已堆积下来,然后被携沙水流所代替;⑨该泥石流沟仍有发生泥石流的可能性;⑩三坪子沟100a一遇泥石流输送到雅砻江的泥沙量在3×104m3以下。因此,即使未来发生100a一遇的泥石流,对上、下闸址也不会构成直接威胁。     

Crustal structure and sedimentation history over the Alleppey platform,southwest continental margin of India:Constraints from multichannel seismic and gravity data

The Alleppey Platform is an important morphological feature located in the Kerala-Konkan basin off the southwest coast of India. In the present study, seismic reflection data available in the basin were used to understand the sedimentation history and also to carry out integrated gravity interpretation. Detailed seismic reflection data in the basin reveals that:(1) the Alleppey Platform is associated with a basement high in the west of its present-day geometry(as observed in the time-structure map of the Trap Top(K/T boundary)),(2) the platform subsequently started developing during the Eocene period and attained the present geometry by the Miocene and,(3) both the Alleppey platform and the Vishnu fracture zone have had significant impact on the sedimentation patterns(as shown by the time-structure and the isochron maps of the major sedimentary horizons in the region). The 3-D sediment gravity effect computed from the sedimentary layer geometry was used to construct the crustal Bouguer anomaly map of the region.The 3-D gravity inversion of crustal Bouguer anomaly exhibits a Moho depression below the western border of the platform and a minor rise towards the east which then deepens again below the Indian shield. The 2-D gravity modelling across the Alleppey platform reveals the geometry of crustal extension,in which there are patches of thin and thick crust. The Vishnu Fracture Zone appears as a crustal-scale feature at the western boundary of the Alleppey platform. Based on the gravity model and the seismic reflection data, we suggest that the basement high to the west of the present day Alleppey platform remained as a piece of continental block very close to the mainland with the intervening depression filling up with sediments during the rifting. In order to place the Alleppey platform in the overall perspective of tectonic evolution of the Kerala-Konkan basin, we propose its candidature as a continental fragment.     

Lowstand ramps,fans and deep‐water Palaeoproterozoic and Mesoproterozoic facies of the Lawn Hill Platform: The Term,Lawn, Wide and Doom Supersequences of the Isa Superbasin,northern Australia

The Term, Lawn, Wide and Doom Supersequences represent tectonically driven, second‐order sedimentary accommodation sequences in the Isa Superbasin. The four supersequences are stacked to form two major depositional wedges or packages extending south from the Murphy Inlier onto the central Lawn Hill Platform. A major intrabasin structure, the Elizabeth Creek Fault Zone separates the two depositional wedges. The Term and Lawn Supersequences each form a thick, crudely fining‐upward sedimentary succession. The basal part of each supersequence comprises sand‐dominated facies, deposited under lowstand conditions. The overlying transgressive deposits comprise thick successions of carbonaceous, shale‐prone sediment that represents times of increased accommodation. Synsedimentary fault activity along the northwest‐trending Termite Range Fault and major northeast‐trending faults including the Elizabeth Creek Fault Zone resulted in overthickened sections of parts of the Term and Lawn Supersequences in regional depocentres. A regional extensional event occurred during Wide Supersequence time, and resulted in strike‐slip deformation, uplift and tilting of fault blocks and erosion of underlying Lawn sequences. This tectonic event created small, fault‐bounded depocentres, where basal silty turbidites of the Wide Supersequence are locally thickened. Denudation of fault blocks in the hinterland provided increasing coarse clastic sediment‐supply forming thick, sand‐dominated, lowstand deposits of the upper Wide Supersequence. Overall, the Wide Supersequence exhibits a coarsening‐upwards facies trend. Tectonic quiescence resulted in the accumulation of siltstone‐dominated transgressive and highstand turbidite deposits in mid‐Wide time. The base of the Doom Supersequence comprises thick, feldspathic, debris‐flow sandstones signalling a new provenance. Decreasing accommodation is reflected by coarsening‐ and shallowing‐upwards facies trends in late Doom time. Declining accommodation and the end of sedimentation in the Isa Superbasin were most likely initiated by deformation at the start of the Isan Orogeny.     

Fracture-zone conditions on a recently active fault: insights from mineralogical and geochemical analyses of the Hirabayashi NIED drill core on the Nojima fault, southwest Japan, which ruptured in the 1995 Kobe earthquake

An 1800-m-deep borehole into the Nojima fault zone was drilled at Nojima-Hirabayashi, Japan, after the 1995 Hyogo-ken Nanbu (Kobe) earthquake. Three possible fracture zones were detected at depths of about 1140, 1300, and 1800 m. To assess these fracture zones in this recently active fault, we analyzed the distributions of fault rocks, minerals, and chemical elements in these zones. The central fault plane in the shallowest fracture zone was identified by foliated blue-gray gouge at a depth of 1140 m. The degree of fracturing was evidently greater in the hanging wall than in the footwall. Minerals detected in this zone were quartz, orthoclase, plagioclase, and biotite, as in the parent rock (granodiorite), and also kaolinite, smectite, laumontite, stilbite, calcite, ankerite, and siderite, which are related to hydrothermal alteration. Biotite was absent in both the hanging wall and footwall across the central fault plane, but it was absent over a greater distance from the central fault plane in the hanging wall than in the footwall. Major element compositions across this zone suggested that hydrothermal alteration minerals such as kaolinite and smectite occurred across the central fault plane for a greater distance in the hanging wall than in the footwall. Similarly, H₂O+ and CO₂ had higher concentrations in the hanging wall than in the footwall. This asymmetrical distribution pattern is probably due to the greater degree of wall–rock fracturing and associated alteration in the hanging wall. We attributed the characteristics of this zone to fault activity and fluid–rock interactions. We analyzed the other fracture zones along this fault in the same way. In the fracture zone at about 1300 m depth, we detected the same kinds of hydrothermal alteration minerals as in the shallower zone, but they were in fewer samples. We detected relatively little H₂O+ and CO₂, and little evidence for movement of the major chemical elements, indicating little past fluid–rock interaction. In the fracture zone at about 1800 m depth, H₂O+ and CO₂ were very enriched throughout the interval, as in the fracture zone at about 1140 m depth. However, smectite was absent and chlorite was present, indicating the occurrence of chloritization, which requires a temperature of more than 200 °C. Only smectite can form under the present conditions in these fracture zones. The chloritization probably occurred in the past when the fracture zone was deeper than it is now. These observations suggest that among the three fracture zones, that at about 1140 m depth was the most activated at the time of the 1995 Hyogo-ken Nanbu (Kobe) earthquake.     

The controls of geomorphology and sediment supply on sequence stratigraphic architecture and sediment partitioning of the lacustrine rift basin in the Es3 of Liuzan area,Nanpu Sag,Bohai Bay Basin,China

An important hydrocarbon reservoir is hosted by the third member of the Shahejie Formation (Es₃) in the Liuzan area, Nanpu Sag, Bohai Bay Basin, China. The Es₃ can be divided into five third-order sequences (from base to top: Sq1, Sq2, Sq3, Sq4 and Sq5). Utilising well logs, cores and high-resolution 3-D seismic data, this study investigates the development characteristics and styles of sediment transport pathways in the steep-slope zone of the lacustrine rift basin. Two styles of sediment transport pathway are identified in the study area, including the faulted trough and fault slope-break zone. The faulted trough is divided into a single faulted trough, synthetic faulted trough and antithetic faulted trough. The fault slope-break zone is composed of synthetic fault slope-break zone and antithetic fault slope-break zone. The fan-delta plain and fan-delta front are recognised in the study area. The different styles of delivery conduits control depositional facies types and the spatial and temporal evolution of fan-delta depositional systems from Sq3 to Sq5. Based on paleo-geomorphological reconstruction, the dispersal pattern of the steep-slope zone system divided into a northern steep-slope system and an eastern steep-slope system is established. In Sq3, the northern steep-slope system develops large-scale mixed sandy–muddy fan-delta deposits derived from the NW. The eastern steep-slope system feeds the medium-scale gravel-rich fan-delta sediments. In Sq4, the large-scale mixed sandy–muddy fan-delta deposits develop from the NNE direction in the northern steep-slope system. The small-scale sand-rich fan-delta sediments are transported from the eastern steep-slope system. In Sq5, the large-scale mixed sand–mud fan-delta deposits are fed by both the northern steep-slope system and eastern steep-slope system. The strata stacking pattern exhibits a seesaw mode in the study area. Based on the analysis of the channel-belt thickness and the fan-scales, the paleogeomorphology of the drainage area in Sq3 and Sq4 and sediment supply in Sq5 alternatively control the sequence stratigraphic architecture and sediment partitioning in the sink area. The model proposed in this study may aid in the prediction of favourable reservoirs and good source–reservoir–seal development in lacustrine rift basin.     

Timing of basin inversion on the Isle of Wight: New evidence from geophysical log correlation, seismic sections and lateral facies change in the Palaeogene Headon Hill Formation

Paleogene thickness patterns across the Bouldnor Syncline and Porchfield Anticline in the northwestern Isle of Wight have been deduced using outcrop information, borehole correlation, gamma-ray logs and seismic reflection data. The thickness patterns provide evidence for an early phase of basin inversion at around the Bartonian-Priabonian boundary (Late Eocene) in the Isle of Wight. Paleogene strata older than the Becton Sand Formation show little evidence for significant lateral changes in thickness, even though the boreholes are located at various structural positions around the Bouldnor Syncline and Porchfield Anticline. In contrast, both seismic reflection and borehole data provide evidence for marked thinning of Paleogene strata onto the Porchfield Anticline at around the level of the Becton Sand Formation and basal Headon Hill Formation (Totland Bay Member) which probably results from an episode of basin inversion and growth folding. The inversion event was relatively minor and short-lived and continues to point toward the main phase of the basin inversion being late Oligocene or younger. However, it still has important implications for understanding structural control on sedimentation patterns in the Headon Hill Formation, with the migration of sandy channelised depositional systems into the axis of the Bouldnor Syncline, and the sequence stratigraphic significance of the important Bartonian-Priabonian regression event, which may related to tectonics rather than global sea-level change.     

Impact of land use change on groundwater quality in a typical karst watershed of southwest China: a case study of the Xiaojiang watershed,Yunnan Province

The impact of land-use change on the quality of groundwater in the Xiaotjiang watershed, China was assessed for the period 1982–2004. Groundwater samples were collected from 30 monitoring points across the watershed, and were representative of the various changes, determined by remote sensing and geographical information systems. The results indicate that 610 km² (60% of the total watershed area) were subject to land-use change during the period. The most important changes were the conversion of 135 km² of forested land to cultivated land, and 211 km² of unused land to cultivated land. The main impact was ascribed to diffuse pollution from fertilizers applied to newly cultivated land, and from building development. Overall the groundwater pH value was significantly increased, as were the concentrations of ions , , , , and Cl⁻ in groundwater whilst the concentrations of Ca²⁺ and declined. More precisely, in the regions where forested land and unused land were converted into cultivated land, the pH value and the concentrations of Mg²⁺, , , , , Cl⁻ increased whilst the concentrations of Ca²⁺ and declined. However in the region where cultivated land was converted into construction land, the pH value and the concentrations of Ca²⁺, Mg²⁺, , , , , , Cl⁻ increased.

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Résumé  L’impact des changements de l’utilisation du territoire sur la qualité de l’eau souterraine dans le bassin versant de Xiaojiang, en Chine, a été évalué de 1982 à 2004. Des échantillons d’eau souterraine ont été récoltés à partir de 30 points d’observation éparpillés sur le bassin, représentant les divers changements déterminés par télédétection et système d’information géographique. Les résultats indiquent que 610 km² (soit 60% de la surface du bassin) ont été sujets à des modifications de l’utilisation du territoire sur cette période. Les changements les plus importants furent la conversion de 135 km² de forêt et 211 km² de terres inutilisées en terres cultivées. Le principal impact est attribué à la pollution diffuse des engrais utilisés en agriculture et pour les batiments. De manière générale le pH de l’eau souterraine a augmenté significativement, ainsi que les concentrations des ions , , , , et Cl⁻, tandis que les concentration en Ca²⁺ et ont diminué. Plus précisément dans les régions transformées en terres cultivées, la valeur du pH et les concentrations en Mg²⁺, , , , , Cl⁻ ont augmenté tandis que les concentrations en Ca²⁺ et ont diminué. Toutefois dans les régions cultivées converties en zones de construction, le pH et les concentrations en Ca²⁺, Mg²⁺, , , , , , Cl⁻ ont augmenté.

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Resumen  El impacto del cambio en uso de la tierra en la calidad del agua en la cuenca Xiaojiang, China fue evaluado para el periodo 1982–2004. Muestras de agua subterránea fueron tomadas de 30 puntos de monitoreo a través de la cuenca, y fueron representativas de los múltiples cambios, determinados por sensores remotos y sistemas de información geográfica. Los resultados indican que 610 km² (60% del área total de la cuenca) estaban sujetos a cambios de uso de la tierra durante el periodo estudiado. Los cambios más importantes fueron la conversión de 135 km² de bosques a tierra cultivada, y 211 km² de tierra sin uso (ociosa) a tierra cultivada. El impacto principal fue causado por contaminación difusa de fertilizantes aplicados a la tierra recientemente cultivada, y a desarrollo de construcciones. En general el pH en agua subterránea creció significantemente, al igual que las concentraciones de los iones , , , , y Cl⁻ en agua subterránea mientras que las concentraciones de Ca²⁺ y decrecieron. Mas precisamente, en las regiones donde bosque y tierra ociosa fueron convertidas en tierra cultivada, el valor de pH y las concentraciones de Mg²⁺, , , , , Cl⁻ crecieron mientras las concentraciones de Ca²⁺ y decrecieron. Sin embargo en la región donde tierra cultivada fue convertida en construcciones, el valor de pH y las concentraciones de Ca²⁺, Mg²⁺, , , , , , Cl⁻ crecieron.

     

大陆碰撞造山带的流体成分与演化:东喜马拉雅构造结南迦巴瓦岩群高压麻粒岩的流体包裹体研究

位于喜马拉雅东构造结的南迦巴瓦岩群经历了高压麻粒岩相、中压麻粒岩相和角闪岩相三期变质作用.在高压麻粒岩中含有复杂的流体包裹体类型,按照捕获先后顺序有:H2O-CO2±CH4包裹体(Ⅰ型);CO2±CH4±N2包裹体(Ⅱ型);高盐度多相包裹体(Ш型);中.低盐度H2O包裹体(Ⅳ型)和极低密度气体包裹体或"空"包裹体(Ⅴ型).在基性麻粒岩中,被石榴石包裹石英中孤立分布的H2O-CO2 4-CH4包裹体,以及部分沿石榴石晶内裂隙分布的H2-CO2±CH4和H2O包裹体轨迹未穿过围绕石榴石的辉石 斜长石后成合晶冠状体,表明它们有可能是在麻粒岩相变质阶段捕获的.然而,所有流体包裹体的等容线均从麻粒岩相变质峰期P-T区间下方通过,说明麻粒岩相变质峰期捕获的包裹体均受到了不同程度的改造,包括部分爆裂、渗漏和流体-矿物相互作用等.现存的富CO2流体包裹体均具有较低密度,并且往往含有明显数量CH4和N2组分,不可能是麻粒岩相变质峰期捕获的包裹体.根据富CO2包裹体与具有不同相比的H2-CO2包裹体共存推测,大部分CO2包裹体是通过H2O-CO2包裹体中H2O的选择性泄漏而形成的.Ⅲ型高盐度盐水包裹体很可能是角闪岩相退变质过程中捕获的,因其等容线与退变质轨迹近于平行,这些包裹体很可能保存了其在角闪岩相阶段捕获时的原生物理化学特征.沿矿物颗粒裂隙分布的大量Ⅳ型和Ⅴ型包裹体,应该是角闪岩相或更晚期形成的次生包裹体,代表了浅成(近地表)环境的循环流体.与世界许多地区麻粒岩相岩石普遍舍高密度纯CO2流体包裹体不同,南迦巴瓦岩群高压麻粒岩以富含H2O-CO4±CH4和H2O包裹体为特征,这可能与高压麻粒岩与高温麻粒岩产出于不同的构造环境和经历的退变质轨迹有关.     

Delineation and interpretation of spatial coseismic response of groundwater levels in shallow and deep parts of an alluvial plain to different earthquakes: A case study of the Kumamoto City area,southwest Japan

Coseismic changes in groundwater levels have been investigated throughout the world, but most studies have focused on the effects of one large earthquake. The aim of this study was to elucidate the spatial patterns of level changes in response to several earthquakes, and the relationship of the patterns to shallow and deep groundwater in the same area. We selected the Kumamoto City area in southwest Japan, a region with one of the richest groundwater resources in Japan, as our study site. Data from hourly measurements of groundwater levels in 54 wells were used to characterize the coseismic responses to four earthquakes that occurred in 2000, 2001, 2005, and 2008. Although the distance to the hypocenter (12–2573 km), and seismic energy (M_w = 5.0–8.0) of these earthquakes varied, systematic groundwater level changes were observed in the range of 0.01–0.67 m. Spatial patters of the level changes were clarified by interpolating the point data by a spline method. The zones where coseismic rises were observed were generally wider for deep groundwater than for shallow groundwater, probably as a result of an increase in compressive stress. General trends in the changes in groundwater levels, and calculated pressure changes, were clarified to be consistent in the deep groundwater, but the coseismic increases or decreases in compressive stress in the shallow groundwater were variable, depending on the distance to the earthquake epicenter. We developed a conceptual model of the mechanism underlying this phenomenon by assuming permeability enhancement induced by elastic strain and pore-pressure change over the depth range. In addition, the importance of local geology was identified, because levels in the area of Togawa lava (a porous andesite) tended to change more in magnitude, and more quickly, with a shorter recovery time, than levels measured in the area outside the lava.