No description available.

No description available.

Brunhes, Matuyama, Kaena and Mammoth age basaltic lava (Selkirk Volcanics - TQS) as well as interbedded sediments were sampled in west-central Yukon Territory, Canada. Paleomagnetic sampling of basalt mapped as TQS along a 370 kilometre transect suggests that early eruptions of TQS occurred coevally over a significant distance to the north of Fort Selkirk. Basal basalt at Ne Ch'e Ddhawa pre-dates continental glaciation in Yukon and is older than the Fort Selkirk Vent (Lower Mushroom), previously thought to be the oldest eruptive vent at Fort Selkirk. The high confining pressures required to form pillow lava suggest subglacial eruptions at Mushroom section. An Early Pleistocene Fort Selkirk glaciation sequence (till and outwash) was reversely magnetized and assigned to the Late Matuyama chron between oxygen isotope stages 62 and 56 inclusive. A lateral moraine on Ne Ch'e Ddhawa was reversely magnetized and therefore assigned to one of the younger Pre-Reid glaciations. i / xi, 123 leaves : ill. (some col.) ; 29 cm.

With the extension of the Nchwaning Mine shaft complex in the Northern Cape Province, various geological and geotechnical complications needed to be identified in order to ensure correct use of tunnelling methods and support techniques. An understanding of the geological history of the area and the resulting geotechnical nature was important in defining the rock mass quality ahead of shaft development. A total of 12 geotechnical boreholes were drilled, and an additional 18 old boreholes revisited to accurately detennine the stratigraphy, geological structure and associated weathering effects. Various soils and rock testing helped quantify the materials encountered. Sands of the Gordonia Fonnation form the surface cover of this area, and together with the weathered calcrete, calc-arenite, conglomerate and clay, they form part of the Cenozoic Kalahari Group. The 30m thick basal unit of red clay is common throughout this region. This silty clay material is problematic in that it is expansive and hygroscopic. The clay unit rests unconformably on folded, faulted and highly weathered shale of the Proterozoic Lucknow and Mapedi Formations of the Olifantshoek Supergroup. Unconformably below this sequence lies the manganiferous ore deposits of the Hotazel Member, which is contained within the Voelwater Formation of the Griqualand West Supergroup. For the development of the decline shaft through the Gordonia Formation a box cut was excavated to a depth of 25m. The anticipated poor geotechnical conditions for a further 125m below the Gordonia sands called for high quality permanent tunnel support in the upper weathered horizons. Barton's Q-analysis was adopted as a recognized tunnelling quality index to predict and quantify the rock mass characteristics ahead of the shaft. The highly variable and generally low Q-values from borehole core analysis indicated that precast tunnel lining be used for 800m (at 11.5°) through the entire weathered Cenozoic sequence and into the weathered shales immediately below the Red Clay. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

No description available.

ENGLISH ABSTRACT: The farm Geelwal Karoo is situated some 16km north of the Olifants River mouth on the West Coast of South Africa and hosts fluvial, marine and aeolian deposits of post-Gondwana age. The oldest basal fluvial succession, unconformably overlies Proterozoic and Palaeozoic basement rocks and is in turn capped by aeolianite and littoral packages representing two transgressive cycles. The fluvial channel clay succession is deposited in shallow bedrock-incised channels, has a wedge-shape and is deposited parallel to the present coastline. The flow direction is along the coast and the northwardtapering, angular, poorly sorted basal vein-quartz lag indicates a northward palaeo-flow direction. Less than 1% total heavy minerals (THM) is found in the matrix of these gravel units and the heavy mineral suite is distinguished by zircon, pseudorutile and kyanite. The channel clay unit is dominated by an upper, mediumgrained quartzose sand and kaolin clay facies, which shows advanced post-depositional weathering. The fluvial unit is correlated with the channel clay unit of Hondeklip Bay and a Cretaceous age is proposed for the initial channel incision. The two shallow marine successions have been correlated with the Late Miocene, Early Pleistocene, +30m and +50m packages respectively. These marine sediments were first described by John Pether (1994) in the Hondeklip Bay area and were named according to their transgressive maxima. They are transgressive successions arranged en echelon down the coastal bedrock gradient, from oldest and highest to youngest. The offshore environment of the +50m package consists of fine silty sand, which is moderately sorted. The mineral assemblage is dominated by quartz and the average THM is 18%. The inshore environment is distinguished by a single poorly sorted basal cobble lag which shows an overall fining upward succession. The beachface environment is composed of medium to fine-grained sand, which is moderate to well-sorted. Mineral diversity is greatest in the inshore and beachface environments and the average THM for these two units is greater than 35%. The +30m package has been extensively eroded due to its lower erosion and outcrops were sporadic along the coast. The +30m offshore sediments are recognised by fine sediments with high concentrations of glauconite and organic matter. The inshore environment is distinguished by numerous poorly sorted pebble lags with fining upward successions. Both the inshore and beachface units have higher feldspar concentrations than the corresponding +50m units. The average THM for these two units is less than 3%. The aeolianite unit, which comprises several distinct units, extends over the entire length of the study area and is characterized by calcrete and red bed horizons. Colour variations in the otherwise homogeneous unit are due to heavy mineral enrichment and/or different degrees of in situ weathering and cementation. The unit is composed exclusively of fine- to medium-grained sand and the THM concentration averages 9%. This unit is composed of more than one generation of aeolian sand and forms part of an aeolian transport corridor which transported sand from the beach to the interior. The oldest unit has been equated with the Upper Miocene Prospect Hill Formation, whereas the more recent yellow dune sand is equated with the Pleistocene Springfontyn Formation. At Geelwal Karoo, only the heavy sand placer in the +50m package was deemed to be of any economic significance. The average THM of this placer was calculated to be 40% and some 150 thousand tons of Tibearing material can be expected from this succession. This relatively small volume of heavy minerals and extensive cementation however, make this placer a less attractive prospect than the neighbouring Namakwa Sands operation. / AFRIKAANSE OPSOMMING: Die plaas Geelwal Karoo is ongeveer 16km noord van die Olifantsriviermond aan die Weskus van Suid- Afrika geleë en het voorkomste van fluviale, marine en eoliese afsettings van post-Gondwana ouderdom. Die oudste eenheid, ‘n basale fluviale eenheid, oorlê Proterosoiëse en Paleosoiëse plaaslike vloer gesteentes wat op hulle beurt weer bedek word deur eoliese en littorale eenhede verteenwoordigene ven twee transgressiewe siklusse. Die fluviale kanaalklei-opeenvolging, afgeset in vlak ingesnyde rotsbedding-kanale, is wigvormig en is afgeset parallel aan die huidige kuslyn in ‘n alluviale waaier-afsetting. Die vloeirigting was langs die kus en die noorwaards toespitsende, hoekige, swak gesorteerde basale aar-kwarts bodemgruis dui op ‘n noordwaards palaeo-vloeirigting. Minder as 1% totale swaarminerale (TSM) is gevind in die tussenmassa van hierdie gruis-eenhede en die swaarmineraal reeks word onderskei deur sirkoon, pseudo-rutiel en kianiet. Die kanaalklei eenheid word oorheers deur ‘n boonste, medium-korrelrige kwarts-bevattende sand en kaolien kleifasies was dui op gevorderde verwering na afsetting. Die fluviale eenheid word gekorreleer met die kleikanaal en ‘n Kryt-ouderdom word voorgestel vir die aanvanklike insnyding van die kanaal. Die twee vlak marine opeenvolgings word gekorreleer met die Laat Mioseen, vroeg Pleistoseen, naamlik die +30m en +50m eenhede onderskeidelik. Die aflandige omgewing van die +50m eenhied bestaan uit matiggesorteerde, fyn slikkerige sand. Die mineraalversameling word oorheers deur kwarts en die gemiddelde TSM is 18%. Die subgetysone word onderskei deur ‘n enkele swak-gesorteerde gruislaag en is oorwegende opwaarts fynerwordend. Die strandomgewing is goed verteenwordige en bestaan uit matig tot goedgesorteerde medium- tot fynkorrelrige sand. Die grootste mineraal-diversiteit kom voor in die subgety- en strandomgewings en die gemiddelde TSM vir hierdie eenhede is hoër as 35%. As gevolg van algemene erosie kom die +30m eenheid sporadies voor. Die aflandige omgeving is herken deur fyn kleierige of slikkerige sedimente met hoe konsentrasies gloukoniet en organiese materiaal. Die subgetysone omgewing is gekenmerk deur verskeie gruislae wat almal opwaarts fynwordend is. Altwee die subgety- en strandomgewings het hoer feldspar konsentrasies as die +50m eenhede. Die gemiddelde THM vir hierdie enhede is minder as 3%. Die eolitiese eenheid, bestaan uit verskeie duidelik-onderskeibare eenhede, beslaan die totale lengte van die studiegebied en word kenmerk deur uitgebreide kalkreet en rooi-laag horisonne. Kleurverskille in die andersins homogene eenheid kan verklaar word in terme van lae swaarmineraal konsentrasies en/of as gevolg wan verskillende grade van in situ verwering en sementering. Die eenheid bestaan uitsluitlik uit fyntot medium-korrelrige sand en het ‘n gemiddelde TSM konsentrasie van 9%. Die eenheid bestaan uit meer as een generasie eoliese sand en maak deel uit van ‘n eoliese vervoersisteem wat sand vanaf die strand na die binneland vervoer het. Die oudste sande in hierdie eenheid is gekorreleer met die Laat Mioseen Prospect Hill Formasie terwyl die meer onlangse geelduin sand vergelyk word met die Pleistoseen Springbokfontein Formasie. By Geelwal Karoo is slegs die +50m eenhede beskou as economies van belang. Die gemiddelde TSM van hierdie swaarmineraal-ertsligaam is bereken op 40% met ‘n verwagte 150 duisend ton Ti-draende material van die opeenvolging. Die relatiewe klein volume swaarminerale en uitgebreide sementering het tot gevolg dat dit ‘n minder aanloklike proposisie is as die aanliggende Namakwa Sands aanleg.

Thesis (MSc)--University of Stellenbosch, 1989. / AFRIKAANSE OPSOMMING: Senosoiese sedimente langs die suidooskus van die Kaapprovinsie is periodiek deur verskeie outeurs vir meer as 'n eeu bestudeer. In hierdie aanbieding word die Iiteratuur saamgevat en vele dubbelsinnige stratigrafiese onderverdelings en definisies opgeklaar. Die Senosoiese afsettings kan volgens oorsprong geklassifiseer word as marien, eolies en fluviaal. Die mariene afsettings, synde strand-, nabystrand-, estuarien of lagunale afsettings geassosieerd met transgressiewe/ regressiewe kusIyne, word nou op grond van kenmerkende litologiese, paleontologiese sowel as ouderdomsverskille onderverdeel in die Paleogeen Bathurst, Neogeen Alexandria en Kwaternere Salnova Foraasies. Die Laat-Plioseen tot Vroeg-Pleistoseen Nanaga Formasie, Middel- tot Laat- Pleistoseen Nahoon Formasie en die Holoseen Schel• Hoek Formasie vorm die kus-eoliese afsettings. AI die mariene en marienverwante (eoliese} formasies, gekenmerk deur kalkige klastiese afsettings, is saamgegroepeer in 'n nuutgedefinieerde Algoa Groep. Fluviale afsettings word onderverdeel in die Martindale, Kinkelbos, Bluewater Bay, Kudus Kloof en Sunland Formasies. Die onderskeie afsettings word gekorreleer met verskillende seevlakstande deur geologiese tye. Die vroegste Senosoiese transgressiewe/regressiewe siklus het in die Vroeg-Paleoseen begin en die hoogste aangetekende elevasie vir die era bereik. Die Bathurst Formasie is waarskynlik gedurende hierdie regressie afgeset. 'n Tweed~ kleiner transgressie/ regressiesiklus het plaasgevind gedurende die Laat-Eoseen tot Vroeg-Oligoseen. Sover tans bekend, kan geen afsetting in die dagsoomgebied van die Algoa Groep definitief met hierdie siklus in verband gebring word nie. Die volgende siklus, wat 'n transgressiewe maksimum van c. 250 m bereik het, het begin in die Middel-Mioseen en verstryk in die Vroee Plioseen. Mariene planasie van die kusplatform het gedurende die transgressie plaasgevind terwyl die Alexandria Formasie wat tans bo 120 m geleë is, gedurende die regressie afgeset is. Die Vroeg-Plioseen transgressie het waarskynlik 'n maksimum huidige hoogte van c. 120 m bereik, waartydens o.a. die 120 m branderstoep en "Humansdorpterras" gekerf is. Die Alexandria Formasie tans geleë tussen 60 en 120 m, is afgeset gedurende die Laat-Plioseen regressie. Hierdie regressie het verskeie relatief lang stilstande, wat waarskynlik die 106-m, 90- tot 100-m en 84-m branderstoepe verklaar, ondervind. Selfs die 60-m en 52-m kuslyne kon tydens hierdie regressie gevorm het. Voorlopige paleontologiese getuienis dui egter daarop dat die 60-m kuslyn 'n transgressiewe maksimum van 'n daaropvolgende siklus verteenwoordig, gevolg deur 'n regressie met minstens een beduidende stilstand by 52 m. Die Alexandria Formasie geleë tussen c. 60 en 30 m, is waarskynlik gedurende hierdie regressie gedeponeer, waartydens ook die Bluewater Bay, Kinkelbos en Kudus Kloof Formasies afgeset is. Gedurende die Kwaternêre transgressie/regressiesiklusse, waarvan minstens vier aangedui word, is die Salnova Formasie (afwesig bo 30 m) afgeset. Die Nahoon Formasie, wat ook op groot skaal op die kontinentale bank ontwikkel is, is gedeponeer gedurende die laaste twee Pleistoseen glasiale toe seevlakke tot benede -100 m gedaal het. Die Schelm Hoek Formasie wat tans nog afgeset word, het ontstaan uit die transgressiewe maksimum van die Flandriese transgressie aan die begin van die Holoseen. / ENGLISH ABSTRACT: Cenozoic sediments along the south-east coast of the Cape Province have been studied intermittently for more than a century by various authors. In this presentation the literature is reviewed and many ambiguous stratigraphic subdivisions and definitions are clarified. The Cenozoic deposits can be classified, according to origin, as marine, aeolian and fluvial. The marine deposits, being lagoonal deposits either beach, nearshore, estuarine or associated with transgressive/regressive shorelines, are now subdivided on the grounds of distinct lithological, palaeontological as well as age differences into the Palaeogene Bathurst, Neogene Alexandria and Quaternary Salnova Formations. The Late Pliocene to Early Pleistocene Nanaga Formation, the Hiddle to Late Pleistocene Nahoon Formation and the Holocene Schelm Hoek Formation constitute the coastal and marine-related aeolian deposits. All the marine (aeolian) formations, which are characterised by calcareous clastics, have been grouped together in a newly defined Algoa Group. Fluvial deposits are subdivided into the Martindale, Kinkelbos, Bluewater Bay, Kudus Kloof and Sunland Formations. The various deposits are correlated with different stands of sea-level through geological time. The earliest Cenozoic transgression/regression cycle started in the Early Palaeocene and reached the highest recorded altitude for the era. The Bathurst Formation was probably deposited during this regression. A second lesser transgression/regression cycle occurred in the Late Eocene to Early Oligocene. As far as is presently known, no deposit in the outcrop area of the Algoa Group can be definitely related to this cycle. The next cycle, which reached a transgressive maximum of c. 250 m, started in the Middle Miocene and terminated in the Early Pliocene. Marine planation of the coastal platform took place during the transgression, whilst the Alexandria Formation presently situated above 120 m, was deposited during the regression. The Early Pliocene transgression is considered to have reached a maximum present-day elevation of c. 120 m, during which the 120 m marine bench and "Humansdorp Terrace", amongst others, were carved. The Alexandria Formation presently situated between 60 and 120 m, was deposited during the Late Pliocene regression, which experienced several relatively long stillstands which probably account for the 106 m, 90 t.o 100 m and 8.4 m benches. Even the 60 m- and 52 m-shorelines could have been formed during this regression. Preliminary palaeontological evidence, however, suggests that the 60 m shoreline represents a transgressive maximum of a subsequent cycle followed by a regression with at least one significant stillstand at 52 m. The Alexandria Formation situated between c. 60 and 30 m, was probably deposited during this regression, which also saw the deposition of the Bluewater Bay, Kinkelbos and Kudus Kloof Formations. During the Quaternary transgression/regression cycles, of which at least four are indicated, the Salnova Formation (absent above 30 m) was deposited. The Nahoon Formation, which is also extensively developed on the continental shelf, was deposited during the last two Pleistocene glacials, when sea-levels receded to less than -100 m. The Schelm Hoek Formation, which is still being deposited, originated from the transgressive maximum of the Flandrian transgression at the start of the Holocene.

Abstract not available

Maps in pocket inside back cover. / Includes published papers and abstracts of works by the author / "November 2003" / Includes bibliographical references. / Various paging : ill. (chiefly col.), maps, plates, charts (some folded) ; 30 cm. + 2 scaled seismic survey maps / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, National Centre for Petroleum Geology and Geophysics and Discipline of Geology and Geophysics, 2004

This study contributes to the understanding of major river evolution in Southeast Asia during the Cenozoic. In order to trace the evolution of a hypothesized palaeo-Yarlung Tsangpo-Irrawaddy River, this work undertakes the first systematic provenance study of detrital minerals from Cenozoic synorogenic fluvial and deltaic sedimentary rocks of the Central Burma Basin, employing a combination of high precision geochronology, thermochronology, and geochemistry analytical techniques on single grain detrital zircon and white mica. The dataset is compared to published isotopic data from potential source terranes in order to determine source provenance and exhumation history from source to sink. A Yarlung Tsangpo-Irrawaddy connection existed as far back as ca. 42 Ma and disconnection occurred at 18–20 Ma, based on provenance changes detected using a combination of U-Pb ages and εHf(t) values on detrital zircons, and ⁴ºAr/³⁹Ar dating on detrital micas. During the Eocene and Oligocene, units are dominated by U-Pb age and high positive εHf(t) values, characteristic of a southern Lhasa Gangdese magmatic arc source. An antecedent Yarlung Tsangpo-Irrawaddy River system formed the major river draining the eastern Himalaya at this time. A significant change in provenance is seen in the early Miocene, where detritus is predominantly derived from bedrock of the eastern Himalayan syntaxis, western Yunnan and Burma, a region drained by the modern Irrawaddy-Chindwin river system characterized by Cenozoic U-Pb ages and negative εHf(t) values. This is attributed to the disconnection of the Yarlung-Irrawaddy River and capture by the proto-Brahmaputra River, re-routing Tibetan Transhimalayan detritus to the eastern Himalayan foreland basin. Re-set zircon fission track ages of 14-8 Ma present in all units is used to infer post-depositional basin evolution related to changes in the stress regime accommodating the continued northward migration of India. The early Miocene initiation of the Jiali-Parlung-Gaoligong-Sagaing dextral shear zone and the continued northward movement of the coupled India-Burma plate aided in focusing deformation inside the syntaxis contributing to the disconnection of the Yarlung Tsangpo-Irrawaddy system, linking surface deformation and denudation with processes occurring at deeper crustal levels.