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In the general framework of seismic hazard analysis for quantifying site amplification, knowledge of the near surface shear wave velocity profile is crucial. The non-destructive and affordable ambient vibration array technique has been shown to be a superior method for estimating this shear wave velocity. The present study seeks to investigate the robustness of shear wave velocity profiles obtained using the ambient vibration array technique at sites exhibiting various (low to high) impedance contrasts by investigating a site in the central business district of Adelaide, South Australia. The city is founded on a regolith, which generally exhibits a range of impedance contrasts, and it is accepted that it is one of the Australian capital cities with the highest seismic risk. Eight ambient vibration array measurements were undertaken across the city. The acquired data were used to invert the shear wave velocity profiles, which are currently very limited, through the analysis of the dispersion characteristics of the surface waves by means of the spatial autocorrelation (SPAC) method, from which a further adjustment was carried out to suit the measured horizontal vertical spectral ratio (HVSR) curve ellipticity. Validation of the proposed shear wave velocity models was carried using previous studies and forward modeling techniques. The present study demonstrates that the SPAC method provides reliable results at regolith sites which are subject to various (low to high) impedance contrasts, provided the frequency band of the captured dispersion curve is wide enough to resolve the investigated depth. The primary innovations of this paper are to: (1) investigate the applicability of the microtremor SPAC method to obtain the near surface shear wave velocity of a low to high impedance contrast site; and (2) propose a new near surface shear wave velocity profile for Adelaide, South Australia.

The data presented in this article contain datasets of passive noise measurements at regolith sites in Adelaide, South Australia. The data were acquired using three component (3C) LE-3Dlite Lennartz seismometers with an eigenfrequency of 1 Hz. The data were acquired at eight sites across Adelaide׳s regolith in a hexagonal array layout. Four tests, each with a duration of 30 min, were conducted at different times. The ambient noise data can be used for both horizontal to vertical spectral ratio (HVSR) analysis and array analyses, which are essential to obtain the site fundamental frequency and the ellipticity of the fundamental mode Rayleigh waves at the measured site. The array analyses are useful to obtain the dispersion curves, which are needed to estimate the shear wave velocity profile. Keywords: Passive noise, Array, HVSR, SPAC, Regolith

Subsurface geometry, particularly the depth of bedrock, is crucial in seismic hazard studies because the basin geometry has been shown to play an important role in the altering of seismic waves. Estimating the bedrock surface using ambient seismic noise analysis has been undertaken by many researchers, with most studies focusing on sites with a strong impedance contrast between the bedrock and the overlying materials. The application of this technique at regolith sites, which is subjected to impedance contrasts in the low to high range is underdeveloped and requires further attention. This study seeks to address this need and is focused on the city of Adelaide in South Australia, which exhibits site amplification and is associated with various impedance contrasts. Analyses of ambient noise data are carried out using the generic function (GF) of the classic horizontal vertical spectral ratio (HVSR) method and the spatial autocorrelation (SPAC) technique to estimate the depth to bedrock. Comparison of the bedrock depth predictions from the seismic methods with boreholes drilled in close proximity to the measured sites demonstrate that the SPAC method provides superior estimates especially to those obtained from the other approach. This work demonstrates that the microtremor SPAC method is an effective tool for estimating bedrock structure at regolith sites.

Seismic site classification is the most widely accepted practical method in the design of seismic resistant infrastructure. The horizontal vertical spectral ratio (HVSR) technique for analyzing ambient noise data has been successfully applied to quantify site effects in the estimation of seismic site classes associated with seismic hazards. This successful application was mainly carried out in high impedance contrast sites. The present paper focuses on the application of the HVSR technique to regolith sites which were suggested by previous studies to be low in impedance contrast between the upper and underlying bedrock layers (

Fine-grained lacustrine, riverine and ash-fall sediments of the Shooting Iron Formation, whose late Pliocene age is established by Blancan gastropods and vertebrates, yield a pollen flora that is essentially similar in composition to the modern pollen rain in the Jackson Hole area. The Pliocene assemblage suggests a climate like that of the Jackson valley and foothills today. These spectra also resemble a Pliocene pollen flora from Yellowstone Park dated at ∼ 2.02 Ma. However, the underlying Miocene Teewinot sediments differ by containing pollen of four exotic deciduous hardwoods (Tertiary relicts) that suggest a summer–moist climate, unlike that of today. The Shooting Iron sediments lie with an angular unconformity on and above the Miocene lake sediments of the Teewinot Formation. Both of these deposits probably preceded the main uplift of the Teton Range based on the absence of Precambrian clasts in the Tertiary valley deposits. Because the Pliocene floras were modern in aspect, a Plio-Pleistocene transition would be floristically imperceptible here. The sequence denotes a protracted period of relative stability of climate during Teewinot time, and a shift in vegetational state (summer–wet trees drop out) sometime between the latest Miocene and latest Pliocene. The Pliocene spectra suggest a dry, cooler climate toward the end of Shooting Iron time.

The Mzingwane River is a sand filled channel, with extensive alluvial aquifers distributed along its banks and bed in the lower catchment. LandSat TM imagery was used to identify alluvial deposits for potential groundwater resources for irrigation development. On the false colour composite band 3, band 4 and band 5 (FCC 345) the alluvial deposits stand out as white and dense actively growing vegetation stands out as green making it possible to mark out the lateral extent of the saturated alluvial plain deposits using the riverine fringe and vegetation . The alluvial aquifers form ribbon shaped aquifers extending along the channel and reaching over 20 km in length in some localities and are enhanced at lithological boundaries. These alluvial aquifers extend laterally outside the active channel, and individual alluvial aquifers have been measured with area ranging from 45 ha to 723 ha in the channels and 75 ha to 2196 ha on the plains. The alluvial aquifers are more pronounced in the Lower Mzingwane, where the slopes are gentler and allow for more sediment accumulation. Estimated water resources potential ranges between 175,000 m3 and 5,430,000 m3 in the channels and between 80,000 m3 and 6,920,000 m3 in the plains. Such a water resource potential can support irrigation ranging from 18 ha to 543 ha for channels alluvial aquifers and 8 ha to 692 ha for plain alluvial aquifers. Currently, some of these aquifers are being used to provide water for domestic use, livestock watering and dip tanks, commercial irrigation and market gardening. The water quality of the aquifers in general is fairly good due to regular recharge and flushing out of the aquifers by annual river flows and floodwater. Water salinity was found to increase significantly in the end of the dry season, and this effect was more pronounced in water abstracted from wells on the alluvial plains. During drought years, recharge is expected to be less and if the drought is extended water levels in the aquifers may drop substantially, increasing salinity problems.

Zimbabwe has a substantial number of mines and 67 minerals have been mined in the country since 1900 but at present only 30 different minerals are being mined. Exploitation of a variety of ores, in rocks of diverse composition, provides the potential for a range of pollution problems. The severity and extent of contamination differs with the type of minerals mined. This paper presents part of the results of a broad study, carried out across Zimbabwe, which assessed the potential of different mine tailings dumps to cause environmental problems. The dumps considered in the study were divided into six dump types, namely: gold-mine dumps, base-metal mine dumps (dumps associated with the mining of nickel, zinc, copper and lead), minor-metals mine dumps (dumps associated with mining of antimony, arsenic, and selenium), platinum-group metal mine dumps, chromite and asbestos mine dumps, and sulphur (pyrite) mine dumps. The elemental chemistry of the dumps and physical characteristics (pH, total dissolved solids) of the dumps, tailings’ leachates, and stream waters around the dumps were used to assess the potential of the dumps to pollute water bodies. Samples were collected in both the dry and wet seasons. The dispersion and pollution patterns were derived from Eh-pH conditions around the dumps after considering the mobility of the elements present in these dumps under different Eh-pH conditions. In this paper potential to pollute is considered as the likelihood of the elements to disperse under the prevailing conditions at the dump. The concentrations of elements, type of elements and the potential dispersion and pollution patterns from each dump were used to characterise potential risk of water pollution associated with the different dump types. The results showed a slight increase in concentrations of most elements studied in downstream waters compared to upstream waters. The dump conditions varied from acidic to alkaline, and so the elements studied have different mobilities in different dumps. The elements that pose environmental risks differed from one dump type to another thus different dumps have different potentials to pollute the water bodies. From the study it emerged that the minor metals dumps show the worst pollution risk, followed by base metal dumps, gold-mine dumps, platinum group metals mine dumps, chromite asbestos mine dumps and sulphur mine dumps. The pH values of 79% of the waters sampled in streams both before and after the dumps were neutral, though the pH values of the leachates themselves was frequently very acidic (pH

The Beatrice Gold Belt, located 65 km south of Harare, lies astride the Mupfure River, a tributary of the Sanyati River, Zambezi Basin. The belt has been mined for gold since 1900, but was abandoned towards the year 2000. The Mupfure River provides water for commercial agriculture in the local farming areas and smallholder farming in Mhondoro Communal Lands, as well as other users downstream in Chegutu and Kadoma Districts. There were four mines in the belt: Beatrice, Joyce, Argyle and Roma. They are all closed, and rehabilitation has only taken place at Beatrice mine. Each mine is located under 5 km from the Mupfure River, and so run-off from the mines and their dumps can easily reach the main river system. The dominant sulphides are arsenopyrite (FeAsS), pyrite (FeS 2 ), galena (PbS) and stibnite (Sb 2 S 3 ). Gold is generally locked up in sulphides or occurs in close contact to the sulphides, so processing is associated with release of acid, arsenic and metals into streams that flow into the Mupfure River. This study was thus carried out to assess the potential impact of these abandoned mines on the water quality of the Mupfure river and its tributaries. Water samples were collected along the tributaries that drain the mining area, as well as from the mine-shafts. Parameters tested include pH, iron, copper, nickel, lead, zinc, antimony, and arsenic. Chemical results obtained show that the surface water is slightly contaminated with respect to Pb, Zn and Ni. Such contamination is attributed to the mine dumps. However, the near-neutral pH and only slight contamination show that the impact on water quality of the Beatrice mines is largely localised probably due to likely low run-off volumes from the mining sites compared to the rest of the catchment. The slight contamination could also indicate that acid mine drainage is proceeding at a slow rate or the fact that it is in its initial stages. Long term environmental management should therefore focus on controlling the localised impact of the old mines as well as controlling the acid drainage.

The mafic-ultramafic Chimbadzi Hill intrusion in the NW of the Zimbabwe craton is a dyke with inward-dipping margins comprising magnetite peridotite, troctolite and magnetite melatroctolite. The magnetite peridotite is composed of about equal amounts of V- and Ti-bearing magnetite and olivine (∼Fo60). The troctolite is composed of about 50% olivine (∼Fo50-54), 40% plagioclase (An53-58), 7% clinopyroxene and minor apatite and magnetite with ilmenite lamellae. Geochemical trends suggest that the Chimbadzi Hill Intrusion formed by fractional crystallisation from a single initial magma. However, the more primitive magnetite peridotite overlies the more evolved troctolite in the intrusion. This ‘apparent’ inverted stratigraphy may be due to emptying of a fractionated magma chamber from the top, or to floor subsidence during intrusion. U–Pb dating on baddeleyite reveals that the age of the Chimbadzi Hill Intrusion is 2262 ± 2 Ma. This age does not correspond to any known tectono-thermal event in the Zimbabwe Craton or adjacent metamorphic belts. It is ∼300 Ma younger than the late Archean Great Dyke, and ∼230 Ma older than other Paleoproterozoic events in and around the craton. Therefore, it may represent a so far undocumented very early Proterozoic igneous event in the Zimbabwe Craton. The intrusion represents a vanadium resource for Zimbabwe, with titanium potentially being mined as by-product.

The Mazowe Valley contains several of Zimbabwes largest current mining operations, is densely populated and is also a major agricultural area. The urban areas of Bindura, Goromonzi, Shamva, Marondera, Murehwa and Mutoko all draw water from within the Mazowe Valley. Irrigation of commercial crops is also a major water user. Accordingly, managing the impact of mining oper- ations on water quality in the Mazowe Valley must be a major priority for sustainable development in this area. Madziwa Mine, 150 km north-east of Harare, is a case in point. Mining took place between 1966 and 2001. The main sulphides were chalcopyrite, pyrrhotite, pentlandite and pyrite. Waste from the mines plant has been disposed of via a tailings dam, the focus of this study. Surface water samples were collected at 12 sites around the slimes dam and groundwater samples were collected from six bore- holes. The samples were analysed for dissolved metals using atomic absorption spectrometry and for anions using gravimetry and titration. The surface water chemical analyses showed that acidic effluent with high concentrations of iron, nickel and sulphate emanates from the tailings dam. Concentrations of metals are lower after the water has passed through natural wetlands. Chemical analysis of groundwater showed similarly high levels of acidity, sulphate and metal. These findings show that acid mine drainage is seeping from the tailings dam. Efforts are being made to reduce the effects of the acid mine drainage. For surface seepage from the dumps these efforts include diverting acidic effluent from the dump into natural wetlands that neutralise the acidity. To reduce drainage into the groundwater efforts are being made to plant trees with high evaporation rates to minimise the amount of water that can cause acid mine drainage. 2004 Elsevier Ltd. All rights reserved.

Vanadium reserves are in the Phosphoria Formation of the Afton area, western Wyoming. The vanadium is in shale and mudstone beds in the Meade Peak Member of the Phosphoria Formation (Permian). Exploration work by the U.S.Geological Survey from the late 1930s to 1943 demonstrated that the vanadiferous zone is remarkably consistent in character, grade, thickness, and lateral continuity throughout the Afton and adjacent 1,000 square mile mountainous area. During the program of exploration and development, in cooperation with the U.S. Bureau of Mines, 123 trenches were dug across surface sections of the Meade Peak Member. Four shafts and six adits were driven into four lines of outcrop of the vanadiferous zone along Dry Creek. On the basis of these data, reserves of about 30 million tons of "indicated" vanadium ore averaging 1.1 percent V 2 O 5 are estimated. The richest central 2.1 feet of the vanadiferous zone is black shale, oolite, and dark-gray mudstone. The tonnage estimate is based in part on ore above main drainage levels and for an arbitrary 500 feet below drainage levels. Factors favorable to possible economic development of the vanadium deposits in the Afton area are the large "indicated" ore reserves and the topographically high areas above drainage levels. Unfavorable factors are the rough terrain, harsh climate, and narrow width of the ore bed. Nearby sources exist for coal, salt, and sulfur, which at the time of this study were necessary for processing the ore. This study demonstrates how a successful field exploration program can be completed under Spartan conditions, and a similar program to the north in the future could be immensely rewarding. About 1,000 square miles of similar mountainous terrain north of the Afton area contain many lines of Phosphoria outcrops that have not been explored adequately for vanadium, gold, silver, chromium, zinc, cadmium, and other trace elements known to be present.

Iron Duke Mine is the only active pyrite mine in Zimbabwe, and has been in operation since the 1940s. Its location in the multiple-use upper catchment of the Mazowe Valley is strategic in terms of water resource management. The mine disposes of its highly acidic wastewater into two evaporation ponds on the north-eastern side of the mine. This has led to acidification of the groundwater to a pH of about 2 near the evaporation ponds as well as contamination with Fe, Ni, Cu, Co, Pb, Zn and SO4 2-. The pH gradually increases in a north-westerly direction, but much faster towards the west and south-west. Water samples taken from the Yellow Jacket River, which runs through the mine premises, indicated that the upper part of the river was not contaminated with Fe, Ni, Cu, Co, Pb, Zn or SO4 2- and had a neutral pH. However, where the river cuts through gossans and passes adjacent to the mine waste dump and the seepage zone from the evaporation ponds, the water quality deteriorates. The symptoms are a reduction in pH of river water from 7 to about 4 and the precipitation of complex iron hydroxy-sulphates known as “yellow boy” on the streambed. Fe, Ni, Cu, Co, Pb, and Zn concentrations are also elevated here. This poor water quality persisted downstream until the confluence with the Mazowe River where the acidic waters were diluted, and the pH returned to 7. The poor water quality in the Yellow Jacket River is related to an overall reduction in the diversity of aquatic macro-invertebrates and fish downstream of the mine until the confluence with the Mazowe River. Water SA Vol. 31 (2) 2005: pp.219-228

Development of New Mexico's energy resources and concomitant utilization of other resources produce unavoidable impacts on the environment. Although areas involved in specific projects are comparatively small, the cumulative extent of impacted areas is substantial. Currently, required studies of impacts produce inventories and descriptions of discrete subjects (e.g., climate, water quality, soils, biota, archeology, paleontology, etc) without relating the subjects to a larger system, or more completely analyzing their scientific potential in the context of natural systems. Historical geology provides a framework for a unified study of the dynamics of the predevelopment environment. This synthetic approach indicates which data are redundant and what further data are needed provides a long-term baseline for evaluating impacts of development, and provides insights for mitigation of adverse impacts. Because historical geology considers the chronology of changing landscapes and their ecology, the environmental context of data is essential for reconstructing the End_Page 563------------------------------ past. Geologists in research and regulatory organizations should determine which data are needed to describe the geologic history of affected regions to alert developers and impact assessors of potential areas for further investigation. The historical-geology approach to evaluating impacts is beneficial to both energy industries and the public because adequate rehabilitation can only be based on an understanding of the dynamics of the affected system. End_of_Article - Last_Page 564

No consistent terminology or boundary delineation has been adopted for the 3 Tertiary sedimentary and structural basins in southwestern Wyoming. The name Green River basin is applied to the downwarp W. of the Rock Springs uplift; it has a significantly different history of erosion and sedimentation than the Great Divide and Washakie basins. The structural basin NE. of the Rock Springs uplift and N. of the Wamsutter arch is called the Great Divide basin, whereas the structural basin SE. of the Rock Springs uplift and S. of the Wamsutter arch is called the Washakie basin.

Four new formation names are used herein for hitherto undescribed or inadequately described rocks in the Jackson Hole region, Teton County, Wyoming: The name Harebell formation is used for a 5,000-foot succession of quartzite pebble conglomerate, olive-drab to gray sandstone, drab-colored siltstone, claystone, and shale of Late Cretaceous age unconformably overlying older Cretaceous rocks and unconformably overlain by Paleocene and younger Tertiary rocks. The name Colter formation is used for a 7,000-foot sequence of white, gray, green, and brown, water-laid basic pyroclastic conglomerate, tuff, sandstone, and claystone of middle Miocene age, unconformably overlying all older rocks and unconformably overlain by rocks of middle Pliocene age. The name Teewinot formation is used for 5,000 feet or more of white limestone, pumicite, tuff, claystone, diatomite, and conglomerate of middle Pliocene age, unconformably overlying all older rocks and unconformably overlain by strata of late Pliocene or Pleistocene age. The name Bivouac formation is used for 1,000 feet of poorly lithified conglomerate interbedded with less amounts of sandstone, siltstone, claystone, pumicite, and welded rhyolite tuff of late Pliocene or Pleistocene age, unconformably overlying rocks of middle Pliocene age, and unconformably overlain by glacial and integlacial deposits of Pleistocene age.

From introduction: This report summarizes the location, gross geologic features, and natural resources of the major sedimentary basins in the United States, excluding Alaska and Hawaii.