John L Keeling - Academia.edu (original) (raw)

Uploads

Papers by John L Keeling

... at Kambalda in 1966, Western Australia has been a major world producer of nickel. The deposit... more ... at Kambalda in 1966, Western Australia has been a major world producer of nickel. The deposits are all hosted by komatiitic rocks, and represent the only significant resources of sulfide Ni in Australia, although small deposits are known elsewhere (eg Avebury, Tasmania). ...

Bookmarks Related papers MentionsView impact

Chemical Geology, Jul 1, 2021

Abstract Dolomite can form the major mineral component of marlstones, and limestones and is an im... more Abstract Dolomite can form the major mineral component of marlstones, and limestones and is an important sink for Magnesium in the different geogene environments such as oceans. The Mg-distribution in the Earth crust and mantle is partly controlled by dolomite in various crystal structures. The genesis of dolomite record important geochemical and environmental processes in the Earth's element cycle. The human society seeks dolomite as an ideal place for CO2-storage, and it is used for management and maintenance of the environment, and in various industrial processes. Dolomite hosts several important ore deposits and major fossil fuel occurrences. The review brings together new advances and insights from recent studies on dolomite structure, geological genesis, laboratory synthesis, and applications. In the mantle, dolomite may adapt to increasing pressure by structural rearrangement and undergoes crystal phase transitions. At present, four high-pressure polymorphs have been identified. The phase transitions allow dolomite to survive subduction into the mantle, possibly into the transition zone, but stability is not fully predictable and is influenced by factors that include initial degree of cation ordering in dolomite and Fe and Mn substitution for Mg in the dolomite crystal lattice. The presence of Fe and Mn is influenced by the environment of dolomite formation. The key factors controlling formation of dolomite, including transition or recrystallization from precursor high-Mg calcite or proto-dolomite, at low temperatures remain ambiguous. Sulfate-reducing bacteria, methanogens, and aerobic bacteria, the exudates or relevant extracellular polymeric substances, fluctuating environmental conditions, and the negatively charged surfaces of clay minerals all can mediate high-Mg calcite/proto-dolomite formation at low temperature. As for secondary dolomite, formed by Mg2+ replacement of Ca2+ in carbonate minerals, several models have been proposed and widely adopted, including: near-surface dolomitization, burial dolomitization, and hydrothermal dolomitization. The formation of massive deposits of dolomite in marine sediments probably involves multiple dolomitization processes. Yet the “dolomite problem” remains enigmatic. Mg isotope analysis, an emerging technology, offers a new approach to further investigate the genesis of dolomite. In the laboratory, synthesis of dolomite at low temperature has yet to be achieved. Fundamental scientific research on dolomite is expected to inform the sustainable use of dolomite resources. Traditional uses of dolomite typically in construction materials, refractory, and flux continue. Now, the use of dolomite and its calcined products is being expanded into environmental protection, soil improvement, thermochemical energy storage and biomedical materials.

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Clay for refractories and acid resistant bricks, Heat Containment Industries, South Australia$

Bookmarks Related papers MentionsView impact

South Australia found as the result of follow up of airborne spectral targets. They add to the gr... more South Australia found as the result of follow up of airborne spectral targets. They add to the growing list of newly discovered kimberlite bodies within the Flinders Ranges and Nackara Arc exploration project areas of Flinders Diamonds Ltd (FDL). Between September 2004 and June 2005, FDL discovered 37 new kimberlites through the use of airborne and ground magnetic surveys (Wills, 2005a). Integration of hyperspectral surveys with the proven technique of low-level magnetics offers a means of locating and prioritising shallow kimberlite targets, including those with a subtle magnetic anomaly.

Bookmarks Related papers MentionsView impact

Journal of Environmental Chemical Engineering, 2021

Abstract Halloysite nanotubes (Hal) with unique nanosized tubular structures are promising nanocl... more Abstract Halloysite nanotubes (Hal) with unique nanosized tubular structures are promising nanoclay for potential applications as reinforcement fillers, anticorrosion coatings, as well as drug carriers, and adsorbents. Thus far, previous studies on acid treatment of Hal have focused only on Hal from a single source under various conditions of acid strength, temperature, and treatment duration. This study is the first to characterize and compare the effects of acid treatment on three types of Hal (Dragonite (DG), HalloPure (HP), and Camel Lake (CLA)) sourced from different geological deposits, and the results considered in terms of their suitability for various applications. Analyses revealed porous tubular structure with an increased lumen diameter of up to 78% and improved surface area from 54 m2g-1 to 160 m2g-1 on acid-treated CLA (acid-CLA). By comparison, lumen diameters were reported to increase by only 46% and 52% for acid-DG and acid-HP, respectively. Despite that, crystallinity of acid-DG decreased the most, from 64.5% to 59.4%, with a high recorded surface area of 229 m2g-1, whereas crystallinity of acid-HP decreased the least from 62.5% to 61.1% with a surface area of 121 m2g-1. Therefore, results obtained support the hypothesis that various Hal can be affected differently by acid treatment, and not all types of Hal are suitable for acid treatment, especially for those intended for use as reinforcement materials.

Bookmarks Related papers MentionsView impact

Precambrian Research, 2017

Bookmarks Related papers MentionsView impact

Ore Geology Reviews, 2017

Bookmarks Related papers MentionsView impact

Ore Geology Reviews, 2017

Abstract The processes leading to the formation of beach placer deposits generally begin inland a... more Abstract The processes leading to the formation of beach placer deposits generally begin inland and terminate at the coast, including source rocks being weathered, eroded and then transported by streams and rivers to the coast, where the sediments are deposited in a variety of coastal environments. The coastal sediments are reworked by the action of waves, tides, longshore currents and wind, which are effective processes for sorting the mineral grains based on differences in their size and density, resulting in laminated or lens-shaped packages of sediments up to tens of meters thick that are rich in heavy minerals. Detailed studies of sedimentary basins, as well as peripheral (paleo-)valleys that drained sediment source areas, are important tools in the exploration for heavy mineral resources. Knowledge of the (paleo-)basin, associated valley architecture and the source of heavy minerals concentrated in the shorelines and valleys are useful guides to the potential for, and location of, economic deposits. Evidence from sedimentology can be combined with that from other geological and geophysical characteristics to arrive at a general reconstruction of basin and paleovalley architecture and depositional environments. Complex paleogeography of the shorelines can influence or determine the sites of heavy mineral concentration. Heavy mineral sands tend to concentrate in certain shoreline settings during storm activity. Repeated storm erosion and reworking over centuries (e.g., the southeastern coast of Australia) or millennia (e.g., the Eucla and Murray Basins of Australia) can progressively enrich heavy mineral sand deposits. Preservation of these deposits over a geological timeframe of millions of years can ensue through subsidence of coastal sediments, and during sea-level change that results in either shorelines migrating inland (marine transgression) or seaward (marine regression), potentially burying or stranding earlier deposits or reworking them to form younger deposits. Refinements in remote sensing and geophysical techniques, data processing, sedimentology and computer-aided interpretations provide effective, economic and efficient methods for modeling coastal reconstructions and for exploring provinces and terrains prospective for heavy mineral sand deposits. Landscape topography analysis, combined with geophysical methods that can resolve physical property contrasts between the shoreline sediments and underlying sequences, are increasingly used in mineral exploration to locate and to reconstruct paleoshorelines and paleovalleys. Australia has modern and ancient beach-placer deposits, both of which show many similar geologic features. The formation of these heavy mineral deposits provides one of the best examples of applying knowledge of modern systems (e.g., the west and east coasts of Australia) as an analogue to interpret and understand the geology and form of ancient deposits (e.g., the Eucla and Murray Basins of southern Australia). This study provides descriptive and exploration models of Australia’s heavy mineral sand deposits formed in coastal environments, which can be applied to similar settings worldwide.

Bookmarks Related papers MentionsView impact

Clay Minerals, 1993

A method of infrared (IR) analysis for quantitative determination of tubular halloysite in mixtur... more A method of infrared (IR) analysis for quantitative determination of tubular halloysite in mixtures with kaolinite was investigated for drill hole samples collected during an assessment of paper-coating kaolin resources at the Mount Hope Kaolin Deposit, Eyre Peninsula, South Australia. Tubular, dehydrated halloysite from the deposit does not readily intercalate formamide, and the proportion of tubes in <2 μm size-fractions was determined initially from scanning electron micrographs. For samples showing a range of tube contents, a strong correlation between IR spectral response and counts of halloysite tubes was established using partial leastsquares analysis. This provided a rapid technique suitable for routine determination of tubular halloysite in samples from the Mount Hope deposit. Although the universality of the method remains to be tested, it offers an alternative approach to other analytical techniques for assessment of kaolin deposits where the presence of halloysite is ...

Bookmarks Related papers MentionsView impact

Applied Clay Science, 2013

Bookmarks Related papers MentionsView impact

Applied Clay Science, 2013

Bookmarks Related papers MentionsView impact

Chemical Geology, Jul 1, 2021

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Clay for refractories and acid resistant bricks, Heat Containment Industries, South Australia$

Bookmarks Related papers MentionsView impact

Journal of Environmental Chemical Engineering, 2021

Bookmarks Related papers MentionsView impact

Precambrian Research, 2017

Bookmarks Related papers MentionsView impact

Ore Geology Reviews, 2017

Bookmarks Related papers MentionsView impact

Ore Geology Reviews, 2017

Bookmarks Related papers MentionsView impact

Clay Minerals, 1993

Bookmarks Related papers MentionsView impact

Applied Clay Science, 2013

Bookmarks Related papers MentionsView impact

Applied Clay Science, 2013

Bookmarks Related papers MentionsView impact

Report Book 2022/00011, 2022

The Cenozoic Eucla Basin, located on the southern margin of the Australian continent with an onsh... more The Cenozoic Eucla Basin, located on the southern margin of the Australian continent with an onshore margin extending over 2,000 km from Western Australia into South Australia, comprises a thin passive margin succession that extends from onshore to more than 500 km offshore, to the approximate foot-of-slope of the Australia’s continental margin. The basin contains a large onshore province of up to 300 m thick marine and coastal sediments of Cenozoic age, linked to an extensive network of peripheral paleovalleys that drained the Precambrian Yilgarn
Block, Gawler Craton, Musgrave Province and Officer Basin.

Understanding the geology and sedimentary evolution of the Eucla Basin and peripheral paleovalleys has relevance to the exploration for placer deposits (e.g., gold, heavy minerals), secondary geochemical deposits (e.g., uranium) and for saline and rarely potable groundwater resources in the basin and channel sediments. Knowledge of the basin and paleovalley architecture and any concentration of minerals in the channels is also of interest as guides to the location of both paleochannel and bedrock lode deposits in the surrounding cratons (e.g., Yilgarn and Gawler). Geoscientific datasets have been integrated in an investigation of this Cenozoic basin and peripheral paleovalleys that have significance for mineral exploration. The objective of the study was to understand the basin characteristics and history, and develop a comprehensive
spatial-depositional model to assist exploration in such huge basin-paleodrainage terrains. This was achieved through the combination of results from various geographical, geological and geophysical datasets. These include interpretations drawn from field observations, a compendium of geological and drilling data, computer modelling of ancient landscapes, topographic and evaluated digital elevation models, remote sensing imagery, geophysical data (e.g., magnetics, seismic,
gravity, airborne and transient electromagnetics and radiometrics, where available), all of which have contributed to a systematic investigation of both shape and depth of the basin-paleodrainage terrains. Physical property contrasts that exist between the basin/channel sediments and the underlying bedrocks, for instance, can be differentiated: by geophysical methods to locate the basin framework and paleoshorelines/paleovalleys.

Evidence from sedimentology was combined with other geological, geomorphological and geophysical characteristics to arrive at a general reconstruction of basinal and paleovalley architectures and depositional environments. The paleovalleys were incised originally into the pre-Cenozoic landscape, mostly weathered basement and Paleozoic and Mesozoic sediments, and became the sites where fluvial, lacustrine, estuarine and marine sediments accumulated during the Paleogene and
Neogene. The application of sequence stratigraphy and facies analysis across the basin and adjacent paleodrainage network were integrated to establish the changes experienced in the basin and paleovalleys as conditions, notably sea level and sediment supply, fluctuated.

This study is a review and synthesis of geoscientific research undertaken in the Eucla Basin, southern Australia during last two decades. Over that time, various investigations have been made of the geophysical and geological characteristics of the Eucla Basin and paleovalleys, and related mineralisation. These projects, particularly in the eastern basin, have assisted exploration, and provide fundamental data for increasing knowledge of geological processes and landscape evolution within this important region. This report largely reviews previous results to develop a better understanding of the characteristics, geometry, geomorphology, and geological/depositional environment of the whole basin and on mineralised sediments associated with placers and uranium deposits on the margins of the Eucla Basin.

Bookmarks Related papers MentionsView impact