Mineralization of the South Pennine Orefield, UK—A Review

2016 ◽  
Vol 61 (1) ◽  
pp. 55-86 ◽  
Author(s):  
T.D. Ford ◽  
N.E. Worley

This review of the South Pennine Orefield (SPO) draws together the findings from many years of underground field observations and petrographical study. Mineralization is of the Mississippi Valley-type (MVT) and is concentrated within an area of some 200 km2, mainly along the eastern margins of a large inlier, the Derbyshire High, in Carboniferous platform carbonate host rocks. The inlier covers some 390 km2, forms an up-dip promontory of a larger structure, the East Midlands Shelf, and is surrounded by shales and sandstones of the Millstone Grit and Pennine Coal Measures groups. Mineralization probably began during the late Westphalian (Moscovian, Mid Pennsylvanian), when subsidence due to thermal sag resulted in the limestone being buried to depths of c. 4 km beneath younger strata. A palaeohydraulic reconstruction is presented from analysis of mineralized palaeokarst features, which are interpreted as representing hypogenic or deep-seated karst formed by the interstratal circulation of hydrothermal water in a mostly confined hydrodynamic setting. It is reasoned that Variscan inversion of N–S faults to the east of the SPO resulted in erosion of Namurian and Westphalian (Upper Mississippian–Middle Pennsylvanian) rocks and created a hydraulic gradient inclined towards the south-west. Acidic F-Ba-Pb-Zn enriched fluid evolved in the Namurian basinal rocks and migrated into fractured limestone. The resultant wall-rock dissolution along existing wrench faults led to the formation of a maze of stratiform mineral deposits (flats) and more irregular spongework-shaped structures (pipes). The presence of hydrocarbon accumulations in the limestones and evidence from fluid inclusions indicates that the mineralizing fluids were chloride/fluoride-rich and compositionally typical of oilfield brine. Isotope evidence demonstrates a sulphate evaporite source of sulphur, mainly from the Chadian (Visean, Middle Mississippian) Middleton Anhydrite Formation. By the late Cenozoic, karstification of exposed carbonate rocks began and the current pattern of epigenic karst drainage started to develop as the regional hydraulic gradient reversed, assuming its present eastward inclined attitude. The mineralized hypogenic karst was overprinted by later drainage systems as the hydraulic gradient changed, and placer deposits were formed from the erosion of existing mineralization. This was accompanied by circulation of meteoric water and resulted in the supergene weathering of the sulphide ore minerals. Eastward underflow of meteoric groundwater also exploited the same mineralization flow paths. There is evidence that pre-mineralization hypogenic karst was also significant in the formation of orebodies in the North Pennine Orefield and the Halkyn–Minera Orefield of NE Wales.

2013 ◽  
Vol 10 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Y. Goddéris ◽  
S. L. Brantley ◽  
L. M. François ◽  
J. Schott ◽  
D. Pollard ◽  
...  

Abstract. Quantifying how C fluxes will change in the future is a complex task for models because of the coupling between climate, hydrology, and biogeochemical reactions. Here we investigate how pedogenesis of the Peoria loess, which has been weathering for the last 13 kyr, will respond over the next 100 yr of climate change. Using a cascade of numerical models for climate (ARPEGE), vegetation (CARAIB) and weathering (WITCH), we explore the effect of an increase in CO2 of 315 ppmv (1950) to 700 ppmv (2100 projection). The increasing CO2 results in an increase in temperature along the entire transect. In contrast, drainage increases slightly for a focus pedon in the south but decreases strongly in the north. These two variables largely determine the behavior of weathering. In addition, although CO2 production rate increases in the soils in response to global warming, the rate of diffusion back to the atmosphere also increases, maintaining a roughly constant or even decreasing CO2 concentration in the soil gas phase. Our simulations predict that temperature increasing in the next 100 yr causes the weathering rates of the silicates to increase into the future. In contrast, the weathering rate of dolomite – which consumes most of the CO2 – decreases in both end members (south and north) of the transect due to its retrograde solubility. We thus infer slower rates of advance of the dolomite reaction front into the subsurface, and faster rates of advance of the silicate reaction front. However, additional simulations for 9 pedons located along the north–south transect show that the dolomite weathering advance rate will increase in the central part of the Mississippi Valley, owing to a maximum in the response of vertical drainage to the ongoing climate change. The carbonate reaction front can be likened to a terrestrial lysocline because it represents a depth interval over which carbonate dissolution rates increase drastically. However, in contrast to the lower pH and shallower lysocline expected in the oceans with increasing atmospheric CO2, we predict a deeper lysocline in future soils. Furthermore, in the central Mississippi Valley, soil lysocline deepening accelerates but in the south and north the deepening rate slows. This result illustrates the complex behavior of carbonate weathering facing short term global climate change. Predicting the global response of terrestrial weathering to increased atmospheric CO2 and temperature in the future will mostly depend upon our ability to make precise assessments of which areas of the globe increase or decrease in precipitation and soil drainage.


1957 ◽  
Vol 3 (21) ◽  
pp. 13-17
Author(s):  
E. H. Muller ◽  
H. W. Coulter

AbstractAn unusual opportunity for the study of glaciers in the process of development is afforded in Katmaicaldera in south-western Alaska. A violent eruption in 1912 destroyed the summit of glacier-clad Mount Katmai, creating a caldera 4 km. wide and 800 m. deep. Ice cliffs produced by beheading of the glaciers have since thinned and shrunk away from the rim of the caldera, except in the south-west. There, local reversal of direction of movement has resulted in an ice fall which descends part way down the crater wall. In the past thirty years two small glaciers have formed, near 1525 m. above sea level, within the caldera on large masses of slumped wall-rock below the north and south rims respectively. Elsewhere the sheer walls of the crater descend so steeply to the level of the caldera lake that permanent snowbanks cannot accumulate. The lake, which continues to rise at a rate of more than five meters per year, is at present the primary deterring factor in glacier development in the caldera.


1957 ◽  
Vol 3 (21) ◽  
pp. 13-17 ◽  
Author(s):  
E. H. Muller ◽  
H. W. Coulter

Abstract An unusual opportunity for the study of glaciers in the process of development is afforded in Katmaicaldera in south-western Alaska. A violent eruption in 1912 destroyed the summit of glacier-clad Mount Katmai, creating a caldera 4 km. wide and 800 m. deep. Ice cliffs produced by beheading of the glaciers have since thinned and shrunk away from the rim of the caldera, except in the south-west. There, local reversal of direction of movement has resulted in an ice fall which descends part way down the crater wall. In the past thirty years two small glaciers have formed, near 1525 m. above sea level, within the caldera on large masses of slumped wall-rock below the north and south rims respectively. Elsewhere the sheer walls of the crater descend so steeply to the level of the caldera lake that permanent snowbanks cannot accumulate. The lake, which continues to rise at a rate of more than five meters per year, is at present the primary deterring factor in glacier development in the caldera.


Author(s):  
Г.П. Яроцкий ◽  
Х.О. Чотчаев

Актуальность рассматриваемой темы в том, что орогенные пояса материковой части Камчатского края насыщены полезными ископаемыми, приуроченных к поясам, образованным последовательным приростом окраин континента от древних с северо-запада к юго-востоку. Такими поясами с месторождениями Ag, Au, Sn, Hg, S являются Северо-Западно-Корякский олигоценовый и Южно-Корякский миоценовый, образованные на северной и южной границе Центрально-Корякской окраины позднемелового континента. Они сформированы в олигоцене и миоцене изолированными вулканогенами локальных андезитовых полей, прорванных гранитоидами тектонической активизации. С ними связаны рудные площади, локализация которых позволит обеспечить прирост запасов разрабатываемых россыпей платиноидов. Цель работы заключается в установлении тектонических закономерностей образования вулканогенов, связанных с ними рудных районов и получения новых данных по их прогнозу. В Северо-Западном поясе оформилась металлогеническая зона с Уннэйваямским, Гайчаваямским и Пальматкинским районами, сопряжёнными с одноименными вулканогенами, в Южно-Камчатском с Ветроваямским вулканогеном. Методология и методы исследования. Методология заключена в глыбово-клавишной структуре литосферы и её земной коры на активных окраинах континента. Методика основана на установлении системной связи структурных элементов геолого-геофизической системы тектоника-вулканогены . Результаты работ и их анализ. Предложена схема закономерностей размещения известных и прогнозируемых рудных районов, узлов юго-запада Корякского нагорья. Они обусловлены глыбово-клавишной тектоникой и локализованы в звеньях серии продольных субпараллельных разновозрастных региональных структур СВ простирания, последовательно наращивающих континент к юго-востоку. Звенья являются дискретными и определяют размеры рудных районов. Рассмотрены выделяемые звенья Северо-Западно-Корякского олигоценового и Южно-Корякского миоценового поясов. В первом СЗ поперечными межглыбовыми разломами литосферы образованы вулканогены гнездового типа. Они возникли на пересечении фундамента позднего мела и южной окраины сопредельной Пенжинской СФЗ поперечными межглыбовыми разломами. В пересечениях образуется литосферный столб вещества гранитоидной активизации верхней мантии и позднемелового осадочного разреза фундамента. Делается вывод, что в Южно-Корякском поясе вулканоген является линейным, образованным заключением линейного СВ Ветроваямского выступа фундамента и чехла между двумя поперечными межглыбовыми разломами. В нём рудоносными вторичными кварцитами создан Ильпинский рудный район с крупными месторождениями самородной серы с Ag, Au, Hg, S. Орогенный вулканизм на активных окраинах континентов сопряжён с основными элементами тектоники и магматизма, создавшими условия образования минерагенических таксонов. На примерах орогенных поясов олигоцена и миоцена очевидна роль геотектонических и металлогенических аспектов авторской методологии глыбово-клавишной структуры литосферы активных окраин. Она эффективна в прогнозе рудных площадей и их оценке последующими геологоразведочными работами. The relevance of the work is that the orogenic belts of the mainland of the Kamchatka Territory are saturated with minerals confined to the belts formed by the successive growth of the continental margins from the ancient ones from the north-west to the south-east. Such belts with deposits of Ag, Au, Sn, Hg, S are the Northwest Koryak Oligocene and South Koryak Miocene, formed on the northern and southern borders of the Central Koryak margin of the Late Cretaceous continent. They are formed in the Oligocene and Miocene by isolated volcanogens of local andesitic fields, broken by granitoids of tectonic activation. Ore areas are associated with them, the localization of which will ensure an increase in the reserves of developed placer deposits. The purpose of the work is to establish tectonic patterns of formation of volcanogens, associated ore regions and obtain new data on their forecast. In the North-Western zone, a metallogenic zone took shape with the Unneivayamsky, Gaichavayamsky and Palmatkinsky regions, associated with the same named volcanogenes, in the South Kamchatka - with the Vetrovayamsky volcanogen. Methodology and research methods. The methodology lies in the block-key structure of the lithosphere and its earths crust on the active margins of the continent. The methodology is based on establishing a systemic connection between the structural elements of the geological and geophysical system tectonics-volcanogens. The results of the work and their analysis. A scheme of patterns of distribution of known and predicted ore regions, nodes of the south-west of the Koryak upland is proposed. They are caused by block-key tectonics and are localized in the links of a series of longitudinal subparallel regionally different age structures of NE strike, successively expanding the continent to the southeast. The links are discrete and determine the size of the ore regions. The distinguished links of the Northwest Koryak Oligocene and South Koryak Miocene belts are considered. In the first northwestern region, nesting volcanogens are formed by transverse interblock faults of the lithosphere. They arose at the intersection of the Late Cretaceous foundation and the southern edge of the adjacent Penzhinsk structural-facial zone with transverse interblock faults. At the intersections, a lithospheric column of granitoid activation matter of the upper mantle and the Late Cretaceous sedimentary section of the basement is formed. It is concluded that the volcanogen in the South Koryak belt, has a linear nature, formed by the conclusion of a linear NE of Vetrovayamsk ledge of the basement and cover between two transverse interblock faults. There ore-bearing secondary quartzites created the Ilpinsk ore region with large deposits of native sulfur with Ag, Au, Hg, S. The orogenic volcanism on the active margins of the continents is associated with the basic elements of tectonics and magmatism, which created the conditions for the formation of minerogenic taxons. The role of geotectonic and metallogenic aspects of the authors methodology of the block-key structure of the active lithosphere margins is evident on the examples of the orogenic Oligocene and Miocene belts. It is effective in forecasting ore areas and evaluating them with subsequent exploration works


2020 ◽  
Author(s):  
Steven Riley ◽  
Kylie E. C. Ainslie ◽  
Oliver Eales ◽  
Caroline E. Walters ◽  
Haowei Wang ◽  
...  

AbstractBackgroundEngland is now in the midst of its second wave of the COVID-19 pandemic. Multiple regions of the country are at high infection prevalence and all areas experienced rapid recent growth of the epidemic during October 2020.MethodsREACT-1 is a series of community surveys of SARS-CoV-2 RT-PCR swab-positivity in England designed to monitor the spread of the epidemic and thus increase situational awareness. Round 6 of REACT-1 commenced swab-collection on 16th October. A prior interim report included data from 16th to 25th October for 85,971 participants. Here, we report data for the entire round on 160,175 participants with swab results obtained up to 2nd November 2020.ResultsOverall weighted prevalence of infection in the community in England was 1.3% or 130 people per 10,000 infected, up from 60 people per 10,000 in the round 5 report (18th September to 5th October 2020), doubling every 24 days on average since the prior round. The corresponding R number was estimated to be 1.2. Prevalence of infection was highest in North West (2.4%, up from 1.2%), followed by Yorkshire and The Humber (2.3% up from 0.84%), West Midlands (1.6% up from 0.60%), North East (1.5% up from 1.1%), East Midlands (1.3% up from 0.56%), London (0.97%, up from 0.54%), South West (0.80% up from 0.33%), South East (0.69% up from 0.29%), and East of England (0.69% up from 0.30%). Rapid growth in the South observed in the first half of round 6 was no longer apparent in the second half of round 6. We also observed a decline in prevalence in Yorkshire and The Humber during this period. Comparing the first and second halves of round 6, there was a suggestion of decline in weighted prevalence in participants aged 5 to 12 years and in those aged 25 to 44 years. While prevalence remained high, in the second half of round 6 there was suggestion of a slight fall then rise that was seen nationally and also separately in both the North and the South.ConclusionThe impact of the second national lockdown in England is not yet known. We provide here a detailed description of swab-positivity patterns at national, regional and local scales for the period immediately preceding lockdown, against which future trends in prevalence can be evaluated.


2011 ◽  
Vol 43 (6) ◽  
pp. 733-749 ◽  
Author(s):  
MONIKA KRZYŻANOWSKA ◽  
C. G. NICHOLAS MASCIE-TAYLOR

SummaryUsing a sample of 2090 father and son pairs, the regional variation in height, weight and body mass index (BMI) with intra- and inter-generational migration within Britain was examined. Highly significant regional differences in means were found only for fathers. The overall mean height difference between regions ranged from about 2.7 cm to 3.1 cm, with the tallest fathers being found in the East & South-East region and the shortest in Wales. The variation in mean weight between regions was less significant, with the difference between the heaviest region (West Midlands) and lightest (South-West) being about 3.5 kg. For BMI the highest mean was in the North and Wales and the lowest in the South-West (difference of about 1 kg m−2). Intra-generational migrants were, on average, significantly taller than non-migrants for both fathers (+1.4 cm) and sons (+2 cm), but BMI was only significant in fathers, with migrant fathers, on average, having a lower BMI. There were no significant differences in weight between geographically mobile groups for either fathers or sons. Differentiating between regional in- and out-migration revealed that in the fathers' generation in-migrants were taller, on average, in six of the nine regions. The tallest in-migrants among fathers came into the North region; the tallest out-migrants were from Yorkshire & Humberside and the shortest were from Scotland. The largest positive gain on fathers' height was in the West Midlands region and Scotland, while negative effects were found in the Yorkshire & Humberside, East Midlands and East & South-East regions. For sons in-migrants were taller in all regions except Wales, with the largest differences between in-migrants and non-migrants being in the South-East and South-West. For out-migrants, the tallest sons came from Wales, while the shortest came from the East Midlands region. The North, East Midlands, East & South-East and West Midlands regions were net gainers, while Wales and Scotland were net losers. For BMI among fathers, in-migrants were of lower BMI than non-migrants. For out-migrant fathers, the North-West and South-West regions were the only two regions showing positive values, with the largest negative values being found in the East Midlands and Yorkshire & Humberside. The net effect of migration indicated that the largest gains were in the East Midlands and Yorkshire & Humberside regions and the largest losses were in Scotland and Wales. The inter-generational migration for BMI showed that in-migrating sons into the North-West and Wales had higher BMI than sedentes, while in-migrants into Yorkshire & Humberside were lower in BMI. In all regions out-migrants had lower BMI than non-migrants. The net effect of migration revealed that six of the nine regions were net gainers, while the Yorkshire & Humberside region was a net loser.


2020 ◽  
Author(s):  
Filipe Temporim ◽  
Ricardo Trindade ◽  
Eric Tohver ◽  
Marcos Egydio-Silva ◽  
Tiago Valim

<p>Large, hot orogens are characterized by an orogenic plateau supported by a zone of weak ductile flow. During the collision phase, the magnitude of the belt and the temperature increase as radioactive crustal material is accreted, buried and heated. After convergence ends, no material is added to the orogenic system and the orogen undergo gravitational (or extensional) collapse that results from the lateral flow of the hot orogenic infrastructure. In the Araçuaí-West Congo orogen (AWO), the high temperatures, slow cooling, and excessive amount of melt in the hinterland, in the northern part of the belt, imply that a high temperature was maintained for a long time. Geochronologic results suggest that this internal domain was hot for a long time, cooling at < 3°/Myr since 600 Ma until 500 Ma, and cooling through the Ar/Ar retention temperature for biotite occurred around 470 Ma. In the south the collapse of the orogen is marked by the widespread intrusion of bimodal, composite plutons at ~500 Ma. Here we use the magnetic fabric (i.e. low-field anisotropy of magnetic susceptibility) of intrusions in the north and south sectors to track the kinematics and rheological changes across the belt. In the northern part of the AWO we studied the Padre Paraíso Charnockite and the southern part of the AWO we studied the Conceição de Muqui and Santa Angélica plutons. The Padre Paraíso charnockite has a coherent magnetic fabric, with magnetic foliations trending N-S, following the general structure of the belt in that sector. In turn, Conceição de Muqui and Santa Angélica plutons show a concentric distribution of foliations and lineations, in starking contrast with the general NE-SW trend of the belt in the south. This contrasting structural pattern for coeaval plutons along the AWO belt reveal the strain partitioning at the scale of the orogenic belt during the cooling of the AWO. At 500 Ma the hot northern sector remains warm enough to allow a coherent deformation of intrusions and host rocks. At the same time, more material was being added to the margins of the hot orogen, which already cold, with the diapire-like plutons structure being dominantly controlled by the forces of magma ascent and emplacement.</p>


1977 ◽  
Vol 81 ◽  
pp. 15-33
Author(s):  
F Ulff-Møller

In the area between Hammers Dal and Gieseckes Dal on north-west Disko (fig. 10) several native iron bearing intrusions have been found over the years (Münther, 1952, 1973; Pedersen, 1975a). Most of these intrusions were formed at shallow depths as volcanic necks of.iron-bearing, highly contaminated intermediate rocks, which probably served as feeders for the lavas of the Niaqússat member ofthe Maligât Formation (Pedersen, 1975a). In addition a series of interconnected subvolcanic intrusions of a very unusual type - the Hammers Dal Complex (Pedersen, 1975a) - were found in 1972 in the south-facing slopes of Hammers Dal extending a few kilometres towards the north-north-wesl (fig. 11 and Plate 2). Nickel and copper-bearing pyrrhotite mineralization was associated with the wall rock of the intrusions and cumu.late zones of native iron were found in the intllJsions themelves. As these were of potential economic interest a detailed investigation of the complex was desirable. [A preliminary description of the Hammer Dal Complex has aiready been given by Ulff-Møller (1975)].


1972 ◽  
Vol 9 (12) ◽  
pp. 1596-1611 ◽  
Author(s):  
Jayanta Guha ◽  
Richard Darling

Microscopic study of samples from the Louvem copper deposit shows that the principal ore minerals are pyrite, chalcopyrite, and sphalerite and the accessory ore minerals are rutile, tetradymite, two unidentified tellurides, cobaltite, molybdenite, galena, and four optically distinct phases having compositions along the digenite–bornite tie line.The Louvem ore body is a pipe-shaped mass of mineralized rhyolitic tuff and agglomerate that is conformable with enclosing volcanic and pyroclastic rocks. The ore body is zoned, with a copper-rich core and pyrite-rich margins. Wall-rock alteration spatially related to the ore deposit suggests that it was formed by replacement of porous tuffaceous host rocks by a hydrothermal fluid. Textural features of the ore indicate that it was subjected to post-emplacement thermal metamorphism.


2012 ◽  
Vol 455-456 ◽  
pp. 1390-1393
Author(s):  
Min Quan Xia ◽  
Gui Wen Xu ◽  
Xue Juan Da ◽  
Lan Chen

This paper presented the Pb-Zn deposits characteristics in southeast Chongqing. The Pb-Zn deposits occurred in Lower-Middle strata with develop the dolomites, limestones as ore-bearing host-rocks. They are veined, stratifed, stratoid, and lenticular in shape and locally pinch and swell with dominant ore minerals of sphalerite, galena, and pyrite . the Pb-Zn ore deposits grade changed from 0.32% to 7.06% for Pb and 4.21% to 14.29% for Zn. The Gaodongzi orebody has highest concentrations of Pb with 7.06% record and Zn with 14.29% record. The tectonic setting, ore-host rocks, wall-rock alternation, and mineral composition will control the Pb-Zn deposits distribution in Chongqing area.


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