Permian Gypsum Research Articles

Origins of Sulfate in Groundwater and Surface Water of the Rio Grande Floodplain, Texas, USA and Chihuahua, Mexico

Sulfate isotopes (δ34S, δ18OSO4) interpreted in conjunction with sulfate concentrations show that sulfate of both agricultural and geologic sources is present in groundwater and surface water in the Rio Grande flood plain within the Hueco Bolsón. From previous studies, water isotopes (δ2H, δ18O) in the study area indicate groundwater age relative to dam construction upstream. Surface water entering the Hueco Bolsón contains a mixture of soil-amendment sulfate and sulfate from deep-basin groundwater seeps at the terminus of Mesilla Valley. In the shallow Rio Grande alluvial aquifer within the Hueco Bolsón, ranges of δ34S in pre-dam (+2 to +9‰) and post-dam (0 to +6‰) groundwater overlap; the range for post-dam water coincides with common high-sulfate soil amendments used in the area. Most post-dam groundwater, including discharge into agricultural drains, has higher sulfate than pre-dam groundwater. In surface water downstream of Fabens, high-δ34S (>+10‰) sulfate, resembling Middle Permian gypsum, mixes with sulfate from upstream sources and agriculture. The high- δ34S sulfate probably represents discharge from the regional Hueco Bolsón aquifer. In surface water downstream of Fort Hancock, soil-amendment sulfate predominates, probably representing discharge from the Rio Grande alluvial aquifer near the basin terminus. The δ18OSO4 dataset is consistent with sulfate origins determined from the larger δ34S dataset.

The Permian gypsum karst belt along the southern margin of the Harz-mountains (Germany), tectonic control of regional geology and karst hydrogeology

The Harz Mountains in Germany are a south-tilting block of variscan-folded Devonian and Carboniferous rocks thrust over Mesozoic sediment along its northern border. Along the South Harz the overlying, unfolded upper-most Carboniferous, Permian and Buntsandstein (lower Triassic) series are exposed in a wide belt. They include a thick series of Upper Permian (“Zechstein”) evaporitic rocks, dipping with about 10° S to SW, representing a nearly continuous sulfate and carbonate karst area about 90 km long, covering 338 km². In his dissertation, the first author compiled a new geological map for the Zechstein at a scale of 1:10,000 and deduced a tectonic model to advance our understanding of the karstic features. Karstification determines the morphology of the South Harz including over 180 registered caves, thousands of sinkholes, uvalas, sinking creeks and large karstic springs. Specifically, lines of sinkholes appear to follow faults. By detailed mapping of the three lowermost Zechstein cycles, a dense matrix of faults is revealed. 85° to 125° striking faults reoccur every few 500 m, formed during the Harz-lifting compressional phase during the Upper Cretaceous. Many of these faults are reverse with a Nward thrust. This leads to repetitive exposure of the strata, causing the broadening of the Zechstein outcrop beyond what would be caused by the dip of the series alone. In other areas, horstand graben-structures are present, resulting in kilometer-long Lower Buntsandstein ridges. Below ground, the groundwater flowing southward along the dip is diverted into the direction of diachronicalthe strike, thus causing strike-parallel depressions, valleys and sinkhole rows. In the final extension phase, faults striking 150° to 180° have caused graben-structures, allowing groundwater and surface rivers to flow southward, breaking through the escarpment of the overlying Lower Buntsandstein. Therefore, the tectonic structure of the South Harz determines its hydrology and the karst features apparent at the surface. The tectonic situation of the three largest karstic springs, the Salza Spring at Förste, the Rhume Spring, and the Salza Spring at Nordhausen is discussed along with more shallow karstic settings of the Hainholz/Beierstein, the Trogstein and the area of Hainrode.

RELATIONS BETWEEN KARST AND THE NEOGENE PALEO-BELAYA VALLEY NETWORK, SOUTHERN CIS-URALS REGION

Miocene-Pliocene tectonic movements transformed considerably the landscape of South Urals and drove spatial patterns and intensity of Earth surface processes. Deepening of river valleys in Paleo-Volga and Paleo-Ural drainage systems facilitated ground water action. Geological section in paleo-valleys of Belaya, Ufa, Bystriy Tanysh, Dioma and other rivers includes up to 200 m thick Late Miocene – Pliocene clayey unit that may favor both drainage and screening of aquifers depending on local hydrogeological conditions. In the former case, karst processes are intensified due to the increased pressure gradients and ground water velocities along the sides of paleovalleys that are composed of Carboniferous and Lower Permian gypsum and limestones. In case of shielding, rising flows of highly mineralized water are discharged in the form of large karst springs (“Krasniy Klyuch”, and others.). Along with natural control factors (lithology, tectonics, hydrogeology, etc.), present-day karstic processes development are controlled by economic activity. Karst and suffosion (underground erosion) are often activated by growth of cities and development of new lands. Neogene and modern valleys promote karst development in Lower Permian gypsums in the Ufa agglomeration where 63 karstic fieds were found. In the last 25 years, 70–80% of hazardous cases related to kasrt intensification were induced by technogenic waterlogging. Karstic and suffusion processes threaten the exploitation of Yumaguzinskaya and – Pavlovskaya Hydropower stations that were constructed on karst prone carbonate rocks at the Belaya and Ufa palevalleys.

RAVINES AND LANDSLIDES OF THE UFA “PENINSULAR”

The Ufa “Peninsular” since active development is experiencing a shortage of land resources due to intensive dissection of Perm massive, on which the city is situated due to constant expansion of the latter. Structuralgeomorphological analysis, using remote sensing materials, field investigations, and drilling data have shown that Permian gypsum, limestone and sandy-clay rocks composing the territory, are divided by vertical and horizontal crustal deformations into blocks of different sizes. As a result, the rock mass was deconsolidated, which caused the intensifi cation of the formation of ravines and landslides.

Shallow seismic reflection profiles over Permian strata affected by gypsum dissolution in NE England

Abstract In NE England, dissolution of Permian gypsum beds has caused subsidence at many localities. We report results from trial 2D profiles at five sites to evaluate the seismic reflection method as a tool for site investigation. At all five sites, the seismic profiles provided potentially useful information. Gypsum beds are imaged at depths in the range 30–70 m, and show evidence of rugose upper surfaces caused by contortion of the strata during rehydration and/or dissolution. The migrated data also reveal structures on the metre scale within the strata overlying the gypsum beds. These structures are interpreted as evidence of foundering as a result of the dissolution of gypsum. Many of them have no expression in the topography at the ground surface. Where gypsum is present at rockhead, the seismic results are generally poor, probably because of the weak contrast in acoustic impedance between hydrated gypsum and unconsolidated superficial deposits. Even this negative result is of value because it indicates that the subsurface may be unstable. As a general strategy, 2D profiles should be acquired at an early stage in site investigation and, if the results are satisfactory, a 3D seismic reflection survey can then be commissioned to provide a geological model of the site.

Hydrogeologic controls on groundwater recharge and salinization: a geochemical analysis of the northern Hueco Bolson aquifer, Texas, USA

Identification of hydrogeologic controls on groundwater flowpaths, recharge, and salinization is often critical to the management of limited arid groundwater resources. One approach to identifying these mechanisms is a combined analysis of hydrogeologic and hydrochemical data to develop a comprehensive conceptual model of a groundwater basin. To demonstrate this technique, water samples were collected from 33 discrete vertical zone test holes in the Hueco Bolson aquifer, located within the Trans-Pecos Texas region and the primary water resource for El Paso, Texas, USA and Juarez, Mexico. These samples were analyzed for a suite of geochemical tracers and the data evaluated in light of basin hydrogeology. On the basis of δ2H and δ18O data, two regional recharge sources were recognized, one originating from western mountain-fronts and one from through-flow of the adjacent Tularosa aquifer. Chloride concentrations were strongly correlated with lithologic formations and both Cl/Br and 36Cl ratios suggested the primary chloride source is halite dissolution within a specific lithologic unit. In contrast, sulfur isotopes indicated that most sulfate originates from Tularosa basin Permian gypsum sources. These results yielded a more comprehensive conceptual model of the basin, which suggested that chloride salinization of wells is the result of upconing of waters from the Fort Hancock formation.

Environmental problems caused by gypsum karst and salt karst in Great Britain

In Great Britain, gypsum karst is widespread in the Late Permian (Zechstein) gypsum of north-eastern England. Here and offshore, a well-developed palacokarst with large breccia pipes was formed by dissolution of the underlying Permian gypsum. Farther south, around Ripon, the same rocks are still being dissolved, forming an actively evolving phreatic gypsum-maze cave system. This is indicated by the presence of numerous active subsidence hollows and sulphate-rich springs. In the English Midlands, gypsum karst is locally developed in the Triassic deposits south of Derby and Nottingham. Where gypsum is present, its fast rate of dissolution and the collapse of overlying strata lead to difficult civil-engineering and construction conditions; these can be further aggravated by water abstraction. Salt (halite) occurs within British Permian and Triassic strata, and has a long history of exploitation. The main salt fields are in central England and the coastal areas of northwest and northeast England. In central England, saline springs indicate that rapid, active dissolution occurs that can cause subsidence problems. In the past, subsidence was aggravated by shallow mining and the uncontrolled extraction of vast amounts of brine. This has now almost stopped, but there is a legacy of unstable buried salt karst, formed by both natural and induced dissolution. The buried salt karst occurs at depths ranging from about 40 m to 130 m; above these depths, the overlying strata are foundered and brecciated. In the salt areas, construction and development are hampered by both abandoned mines and by natural or induced brine runs, with their associated unstable ground.

The sub-basaltic surface in northeast Ireland and its significance for interpreting the Tertiary history of the region

In northeast Ireland a striking unconformity exists between late Cretaceous, marine limestones (Ulster White Limestone Formation) and Paleocene, subaerially emplaced, basalt flows (Antrim Lava Group) above. The well-cemented nature of the Ulster White Limestone has been attributed to thermal or loading effects associated with the Antrim Lava Group. However, the geomorphology of the palaeokarst beneath can be used to demonstrate that both cementation and joint emplacement in the limestone significantly preceded burial beneath the basalts. A thin, irregularly developed palaeosol, dominated by red-brown or grey clay above a relatively thin basal lag of flint debris, is present on the palaeokarst surface. It has been interpreted previously as a Terra Rossa, derived from the accumulation of insoluble residues remaining after limestone dissolution. However, the colour, mineralogy and geochemistry of the clay, and the low proportion of flints to clay, indicate instead that the clay fraction was derived from ash falls, usually basaltic but occasionally rhyolitic, prior to the first lava flows. In the long term the survival of the Permian and Mesozoic sediments in northeastern Ireland cannot be ascribed solely to the supposed ‘carapace’ effect of the Tertiary basalts, with continued basin subsidence from Mesozoic into Tertiary times being of greater significance. However, it did play a role in the shorter term. Variation in the preserved thickness of limestone beneath the basalts at any one site was controlled by three factors; original thickness of the limestone, its elevation in Paleocene times, and the time elapsed between subaerial emergence and burial by the advancing lava flows. Preservation of significant thicknesses of Ulster White Limestone in the western part of the Antrim Plateau, where previous work has indicated that the onset of volcanism was later than in the east, suggests that limestone uplift preceded lava emplacement by perhaps only 10 4 -10 5 years and was due to local thermal doming on a scale of only a few tens of kilometres. Tertiary subsidence must also be invoked for the Kingscourt half-graben further to the south, where friable, autobrecciated basalts overlie a spectacular palaeokarst surface developed on Permian gypsum.

Planning for gypsum geohazards in Lithuania and England

The rapid underground dissolution of gypsum, and the evolution of the gypsum karst in Lithuania and England, results in subsidence problems which can make construction difficult. The natural dissolution yields sulphate-rich groundwater of poor quality and the karst is susceptible to the rapid transmission of pollutants. In the north of Lithuania gypsum karst is developed in Devonian gypsum. Here the towns of Birai, Pasvalys and the surrounding countryside suffer subsidence and some buildings have been damaged. The majority of the potable water in these areas is derived from groundwater extracted from sandstone sequences that underlie the gypsum. In Lithuania conservation measures have been introduced to control agriculture and prevent pollution of the gypsum karst. These measures include environmentally-friendly farming, restrictions on land use and exclusion zones around subsidence hollows. In England subsidence caused by the dissolution of Permian gypsum has caused severe problems in the vicinity of the town of Ripon. Numerous buildings have been damaged and new sites are difficult to develop. Here formal planning regulations have recently been introduced to help to protect against the worst effects of subsidence resulting from gypsum dissolution.

Subsidence hazards caused by the dissolution of Permian gypsum in England: geology, investigation and remediation

Abstract About every three years natural catastrophic subsidence, caused by gypsum dissolution, occurs in the vicinity of Ripon, North Yorkshire, England. Holes up to 35 m across and 20 m deep have appeared without warning. In the past 150 years, 30 major collapses have occurred, and in the last ten years the resulting damage to property is estimated at about £1000000. Subsidence, associated with the collapse of caves resulting from gypsum dissolution in the Permian rocks of eastern England, occurs in a belt about 3 km wide and over 100 km long. Gypsum (CaS0 4 .2H 2 0) dissolves rapidly in flowing water and the cave systems responsible for the subsidence are constantly enlarging, causing a continuing subsidence problem. Difficult ground conditions are associated with caves, subsidence breccia pipes (collapsed areas of brecciated and foundered material), crown holes and post-subsidence fill deposits. Site investigation methods that have been used to define and examine the subsidence features include microgravity and resistivity geophysical techniques, plus more conventional investigation by drilling and probing. Remedial measures are difficult, and both grouting and deep piling are not generally practical. In more recent times careful attention has been paid to the location for development and the construction of low-weight structures with spread foundations designed to span any subsidence features that may potentially develop.

Gypsum karst of Great Britain

In Great Britain the most spectacular gypsum karst development is in the Zechstein gypsum (late Permian) mainly in north-eastern England. The Midlands of England also has some karst developed in the Triassic gypsum in the vicinity of Nottingham. Along the north-east coast, south of Sunderland, well-developed palaeokarst, with magnificent breccia pipes, was produced by dissolution of Permian gypsum. In north-west England a small gypsum cave system of phreatic origin has been surveyed and recorded. A large actively evolving phreatic gypsum cave system has been postulated beneath the Ripon area on the basis of studies of subsidence and boreholes. The rate of gypsum dissolution here, and the associated collapse lead to difficult civil engineering and construction conditions, which can also be aggravated by water abstraction.

Subsidence hazards due to the dissolution of Permian gypsum in England: investigation and remediation : A. H. Cooper, in: Karst geohazards: engineering and environmental problems in karst terrane. Proc. 5th conference, Gatlinburg 1995, ed B.F. Beck, (Balkema), 1995, pp 23–29

Subsidence hazards due to the dissolution of Permian gypsum in England: investigation and remediation : A. H. Cooper, in: Karst geohazards: engineering and environmental problems in karst terrane. Proc. 5th conference, Gatlinburg 1995, ed B.F. Beck, (Balkema), 1995, pp 23–29

Airborne multispectral scanning of subsidence caused by Permian gypsum dissolution at Ripon, North Yorkshire : Cooper, A H Q J Engng Geol V22, N3, 1989, P219–229

Airborne multispectral scanning of subsidence caused by Permian gypsum dissolution at Ripon, North Yorkshire : Cooper, A H Q J Engng Geol V22, N3, 1989, P219–229

Airborne multispectral scanning of subsidence caused by Permian gypsum dissolution at Ripon, North Yorkshire

Abstract Around Ripon, North Yorkshire, catastrophic subsidence locally occurs because of natural underground dissolution in the Permian gypsum. This airborne study assesses the merits of multispectral scanning (MSS) as a method of detecting incipient subsidence areas and as an aid to geological mapping. The multispectral method indicates subsidence areas by vegetation, soil colour and temperature variations. Computer enhancement of the multispectral images allow some subsidence details not seen by conventional photography to be delineated. The MSS images are two-dimensional and even the most detailed ones have a fairly coarse resolution (1.5–2.0m). Because of this, conventional 3D interpretation of stereo air photographs better indicates the morphology of the subsidence hollows and the geology.

Subsidence resulting from the dissolution of Permian gypsum in the Ripon area; its relevance to mining and water abstraction : Cooper, A H Proc 23rd Annual Conference of the Engineering Group of the Geological Society, Engineering Geology of Underground Movements, Nottingham, 13–17 Sept 1987 P487–493. Publ Nottingham: University of Nottingham, 1987

Subsidence resulting from the dissolution of Permian gypsum in the Ripon area; its relevance to mining and water abstraction : Cooper, A H Proc 23rd Annual Conference of the Engineering Group of the Geological Society, Engineering Geology of Underground Movements, Nottingham, 13–17 Sept 1987 P487–493. Publ Nottingham: University of Nottingham, 1987

Subsidence resulting from the dissolution of Permian gypsum in the Ripon area; its relevance to mining and water abstraction

Abstract Because gypsum dissolves rapidly in flowing water the subsurface dissolution of Permian gypsum at Ripon results in severe subsidence. The pattern of subsidence and methods of propagation are similar to those which might result from mining. Breccia pipe propagation and bulking factors for Permian rocks are discussed. The implications both of gypsum dissolution and the forceful expansion of anhydrite by hydration in flooded gypsum mines are assessed. The removal of gypsum and possible subsidence caused by large-scale water abstraction and mine dewatering are also considered.

Subsidence and foundering of strata caused by the dissolution of Permian gypsum in the Ripon and Bedale areas, North Yorkshire

Summary Underground dissolution of thick gypsum beds in the Edlington Formation and Roxby Formation of the Zechstein sequence in North Yorkshire, England, has resulted in a 3 km-wide and 100 km-long belt of ground susceptible to foundering. Within this belt a large subsidence depression at Snape Mires, near Bedale, was largely filled with lacustrine deposits in the later part of the Late Devensian and during the Flandrian. South of Snape Mires the Nosterfield-Ripon-Bishop Monkton area has suffered about 40 episodes of subsidence in the past 150 years, and the presence of several hundred other subsidence hollows indicates considerable activity from the later part of the Devensian onwards. The linear and grid-like arrangement of these subsidence hollows indicates collapse at intersections in a joint-controlled cave system. Linear subsidence features at Snape Mires are also joint-controlled. The transition from anhydrite at depth to secondary gypsum near surface marks the down-dip limit of the subsidence-prone belt. Cavities are propagated upwards by roof collapse of caverns in the gypsum, leading to the formation of breccia pipes. Choking of the pipes can reduce the surface expression of the underground collapse, but the larger cavities are liable to produce pipes that reach the surface even at the eastern boundary of the 3 km-wide belt described. Further subsidence in the Ripon area is predicted and some suggestions for remedial measures are given.

FIELD MEETINGS AND MEDAL PRESENTATIONS 1981

This report describes a one-day field trip to the Ripon area. The trip examined the Permian gypsum cliff at Ripon Parks and the rapidity with which it dissolved. It looked and the associated dolomitic limestones and at subsidence features and building damage in the area.