The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
J J Wilkinson - One of the best experts on this subject based on the ideXlab platform.
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the chlorite proximitor a new tool for detecting porphyry Ore Deposits
Journal of Geochemical Exploration, 2015Co-Authors: J J Wilkinson, C C Wilkinson, Zhaoshan Chang, David R Cooke, Michael J Baker, Shaun Inglis, Huayong Chen, Bruce J GemmellAbstract:Abstract The major, minor and trace element chemistry of chlorite were evaluated as a tool for mineral exploration in the propylitic environment of porphyry Ore Deposits. Chlorite from eighty propylitically altered samples, located up to 5 km from the Batu Hijau Cu–Au porphyry deposit in Indonesia, was analyzed using electron microprobe and laser ablation inductively-coupled plasma mass spectrometry. The results show that a variety of elements, including K, Li, Mg, Ca, Sr, Ba, Ti, V, Mn, Co, Ni, Zn and Pb, are probably incorporated in the chlorite lattice and display systematic spatial variations relative to the porphyry center. Ti, V and Mg decrease exponentially in concentration with increasing distance, whereas the others increase. Ratioing the former to the latter provides a variety of ratios that vary up to four orders of magnitude, providing sensitive vectoring parameters. Chlorite geothermometry suggests that Ti is substituted into chlorite as a function of crystallization temperature and thus maps out the thermal anomaly associated with the mineralized center. By contrast, Mn and Zn display a maximum in chlorite at a distance of ~ 1.3 km that mirrors the whole rock anomaly for these metals, reflecting their lateral advection into the wall rocks by magmatic-hydrothermal fluids. The recognizable footprint defined by chlorite compositions extends to at least 4.5 km, significantly beyond the whole rock anomalism (≤ 1.5 km) and thus represents a powerful new exploration tool for detecting porphyry systems. Variations in chlorite chemistry are very systematic in the inner propylitic zone (to distances of ~ 2.5 km), thereby providing a precise vectoring tool in a domain where other tools are typically ineffective. In this zone, equations of the form: x = ln R a b can be formulated, where the distance to center, x, is predicted based on a variety of element ratios in chlorite R, and where a and b are exponential fit parameters. Importantly, distal chlorite compositions in porphyry-related propylitic alteration systems are also shown to be distinct from metamorphic chlorite, allowing the external fringes of porphyry-related hydrothermal systems to be distinguished from “background” regional metamorphism or geothermal alteration.
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triggers for the formation of porphyry Ore Deposits in magmatic arcs
Nature Geoscience, 2013Co-Authors: J J WilkinsonAbstract:Porphyry Ore Deposits supply much of the copper, molybdenum, gold and silver used by humans. A review of the main processes that trigger porphyry Ore formation suggests that sulphide saturation of the magmas that supply the metals could be the overriding mechanism that helps control the temporal and spatial distribution of the Ore Deposits.
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anomalously metal rich fluids form hydrothermal Ore Deposits
Science, 2009Co-Authors: B Stoffell, J J Wilkinson, C C Wilkinson, Teresa Jeffries, Martin S. AppoldAbstract:Hydrothermal Ore Deposits form when metals, often as sulfides, precipitate in abundance from aqueous solutions in Earth's crust. Much of our knowledge of the fluids involved comes from studies of fluid inclusions trapped in silicates or carbonates that are believed to represent aliquots of the same solutions that precipitated the Ores. We used laser ablation inductively coupled plasma mass spectrometry to test this paradigm by analysis of fluid inclusions in sphalerite from two contrasting zinc-lead Ore systems. Metal contents in these inclusions are up to two orders of magnitude greater than those in quartz-hosted inclusions and are much higher than previously thought, suggesting that Ore formation is linked to influx of anomalously metal-rich fluids into systems dominated by barren fluids for much of their life.
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fluid inclusions in hydrothermal Ore Deposits
Lithos, 2001Co-Authors: J J WilkinsonAbstract:Abstract The principal aim of this paper is to consider some of the special problems involved in the study of fluid inclusions in Ore Deposits and review the methodologies and tools developed to address these issues. The general properties of fluid inclusions in hydrothermal Ore-forming systems are considered and the interpretation of these data in terms of fluid evolution processes is discussed. A summary of fluid inclusion data from a variety of hydrothermal deposit types is presented to illustrate some of the methodologies described and to emphasise the important role which fluid inclusion investigations can play, both with respect to understanding deposit genesis and in mineral exploration. The paper concludes with a look to the future and addresses the question of where fluid inclusion studies of hydrothermal Ore Deposits may be heading in the new millenium.
Mathias S Egglseder - One of the best experts on this subject based on the ideXlab platform.
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tiny particles building huge Ore Deposits particle based crystallisation in banded iron formation hosted iron Ore Deposits hamersley province australia
Ore Geology Reviews, 2019Co-Authors: Mathias S Egglseder, Andrew G Tomkins, Andrea Rielli, Alexander R Cruden, Hilke J Dalstra, Siobhan A. Wilson, Chenghao Li, Jens BaumgartnerAbstract:Abstract The world’s major source of iron Ore is hosted in Precambrian banded iron formations. These chemical (meta-) sedimentary rocks are composed of alternating laminae of iron oxide minerals and chert. Despite the economic significance of high-grade iron Ore Deposits, controversy persists after decades of research on how banded iron formations became upgraded to form iron Ore. The fundamental requirement for iron Ore formation is the removal of vast amounts of chert coupled with an increased concentration of iron oxide minerals. Here, we assess the fate of colloidal hematite inclusions encapsulated in chert after quartz dissolution and examine their role in the formation of hematite Ore. We have analysed hematite Ores from the Hamersley Province (Australia) using a combination of petrography, high-resolution electron microscopy and X-ray diffraction. These techniques reveal the presence of abundant nano and microscale hematite particles that we suggest form the building blocks of larger hematite crystals within the iron Ore. Our textural observations indicate that hematite colloids that were previously encapsulated inside the microcrystalline quartz grains in chert layers are released during quartz dissolution, and subsequently reassemble in a self-similar fashion to from new microplaty hematite crystals via non-classical crystallisation pathways. Progressive growth and fusion leads to the transformation of hematite microplates into hematite bands, which resemble pre-existing iron oxide laminae of banded iron formations. In contrast to previous models, we observe the direct transformation of banded iron formations to microplaty hematite and have not found evidence that significant amounts of hematite formed through metamorphism of goethite or that intermediate carbonate minerals were involved during the upgrading of banded iron formations to pure hematite Ore. Given the strong evidence for hypogene fluids found in many Deposits, we have also assessed the role that such warm, highly saline fluids may have played during the evolution of iron Ore. Using insights from crystal chemistry we conclude that fluid infiltration impacts many aspects of iron Ore formation by controlling hematite colloid liberation and aggregation, and finally controlling the transformation of the colloids into macroscopic crystals of hematite via non-classical crystallisation mechanisms. Our study underlines the significance of hypogene fluids in the upgrading of banded iron formation to iron Ore, however, we suggest that their influence was mainly passive as hematite was not precipitated directly from these fluids.
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the role of deformation in the formation of banded iron formation hosted high grade iron Ore Deposits hamersley province australia
Precambrian Research, 2017Co-Authors: Mathias S Egglseder, Alexander R Cruden, Hilke J Dalstra, Leigh NicholasAbstract:Abstract The Hamersley Province (Western Australia) hosts some of the world’s largest iron Ore Deposits but despite decades of research, their genesis is still extensively debated. Many iron Ore Deposits are hosted in complexly deformed Archean to Paleoproterozoic banded iron formations, comprising thin chert and iron oxide bands interlayered with silicate-rich shales and carbonates. Current iron Ore genesis models have identified a strong structural control on Ore formation linked to extensive hypogene and supergene fluid circulation along fault structures. These fluid pathways facilitate the removal of vast amounts of gangue minerals, leading to enrichment of the iron oxide residue to iron Ore. However, the evolution of the associated structures has not yet been considered as a key element in Ore genesis. Here we show through multiscale structural analyses that deformation not only forms suitable fluid channels, but that folding and shearing also result in significant synkinematic removal of gangue minerals. Our multidisciplinary investigation of the structural evolution of the Mount Tom Price deposit combines microtectonic, field geology and 3D implicit modelling techniques to establish a link between deformation structures at various scales. Microscale shear bands and outcrop-scale asymmetric parasitic folds share striking similarities in their evolution and their controlling mechanisms. Both features record substantial non-coaxial deformation accompanied by volume changes due to stress-induced silica remobilisation. The closely spaced layering of rheologically different lithologies within Hamersley Province strata plays a crucial role in complex multilayer deformation, which resulted in extensive strain partitioning. Our study suggests that deformation was of major significance in the upgrading of banded iron formation to iron Ore and was active from the early stages of banded iron formation during diagenesis. Deformation structures also established a micro- to deposit-scale lateral and vertical fluid network, which enabled infiltration by hypogene and supergene fluids during or after deformation. These new insights have important implications for iron Ore genesis models, structural applications in the mine environment, and for understanding complex multilayer deformation with volume loss.
Hilke J Dalstra - One of the best experts on this subject based on the ideXlab platform.
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tiny particles building huge Ore Deposits particle based crystallisation in banded iron formation hosted iron Ore Deposits hamersley province australia
Ore Geology Reviews, 2019Co-Authors: Mathias S Egglseder, Andrew G Tomkins, Andrea Rielli, Alexander R Cruden, Hilke J Dalstra, Siobhan A. Wilson, Chenghao Li, Jens BaumgartnerAbstract:Abstract The world’s major source of iron Ore is hosted in Precambrian banded iron formations. These chemical (meta-) sedimentary rocks are composed of alternating laminae of iron oxide minerals and chert. Despite the economic significance of high-grade iron Ore Deposits, controversy persists after decades of research on how banded iron formations became upgraded to form iron Ore. The fundamental requirement for iron Ore formation is the removal of vast amounts of chert coupled with an increased concentration of iron oxide minerals. Here, we assess the fate of colloidal hematite inclusions encapsulated in chert after quartz dissolution and examine their role in the formation of hematite Ore. We have analysed hematite Ores from the Hamersley Province (Australia) using a combination of petrography, high-resolution electron microscopy and X-ray diffraction. These techniques reveal the presence of abundant nano and microscale hematite particles that we suggest form the building blocks of larger hematite crystals within the iron Ore. Our textural observations indicate that hematite colloids that were previously encapsulated inside the microcrystalline quartz grains in chert layers are released during quartz dissolution, and subsequently reassemble in a self-similar fashion to from new microplaty hematite crystals via non-classical crystallisation pathways. Progressive growth and fusion leads to the transformation of hematite microplates into hematite bands, which resemble pre-existing iron oxide laminae of banded iron formations. In contrast to previous models, we observe the direct transformation of banded iron formations to microplaty hematite and have not found evidence that significant amounts of hematite formed through metamorphism of goethite or that intermediate carbonate minerals were involved during the upgrading of banded iron formations to pure hematite Ore. Given the strong evidence for hypogene fluids found in many Deposits, we have also assessed the role that such warm, highly saline fluids may have played during the evolution of iron Ore. Using insights from crystal chemistry we conclude that fluid infiltration impacts many aspects of iron Ore formation by controlling hematite colloid liberation and aggregation, and finally controlling the transformation of the colloids into macroscopic crystals of hematite via non-classical crystallisation mechanisms. Our study underlines the significance of hypogene fluids in the upgrading of banded iron formation to iron Ore, however, we suggest that their influence was mainly passive as hematite was not precipitated directly from these fluids.
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the role of deformation in the formation of banded iron formation hosted high grade iron Ore Deposits hamersley province australia
Precambrian Research, 2017Co-Authors: Mathias S Egglseder, Alexander R Cruden, Hilke J Dalstra, Leigh NicholasAbstract:Abstract The Hamersley Province (Western Australia) hosts some of the world’s largest iron Ore Deposits but despite decades of research, their genesis is still extensively debated. Many iron Ore Deposits are hosted in complexly deformed Archean to Paleoproterozoic banded iron formations, comprising thin chert and iron oxide bands interlayered with silicate-rich shales and carbonates. Current iron Ore genesis models have identified a strong structural control on Ore formation linked to extensive hypogene and supergene fluid circulation along fault structures. These fluid pathways facilitate the removal of vast amounts of gangue minerals, leading to enrichment of the iron oxide residue to iron Ore. However, the evolution of the associated structures has not yet been considered as a key element in Ore genesis. Here we show through multiscale structural analyses that deformation not only forms suitable fluid channels, but that folding and shearing also result in significant synkinematic removal of gangue minerals. Our multidisciplinary investigation of the structural evolution of the Mount Tom Price deposit combines microtectonic, field geology and 3D implicit modelling techniques to establish a link between deformation structures at various scales. Microscale shear bands and outcrop-scale asymmetric parasitic folds share striking similarities in their evolution and their controlling mechanisms. Both features record substantial non-coaxial deformation accompanied by volume changes due to stress-induced silica remobilisation. The closely spaced layering of rheologically different lithologies within Hamersley Province strata plays a crucial role in complex multilayer deformation, which resulted in extensive strain partitioning. Our study suggests that deformation was of major significance in the upgrading of banded iron formation to iron Ore and was active from the early stages of banded iron formation during diagenesis. Deformation structures also established a micro- to deposit-scale lateral and vertical fluid network, which enabled infiltration by hypogene and supergene fluids during or after deformation. These new insights have important implications for iron Ore genesis models, structural applications in the mine environment, and for understanding complex multilayer deformation with volume loss.
Alexander R Cruden - One of the best experts on this subject based on the ideXlab platform.
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tiny particles building huge Ore Deposits particle based crystallisation in banded iron formation hosted iron Ore Deposits hamersley province australia
Ore Geology Reviews, 2019Co-Authors: Mathias S Egglseder, Andrew G Tomkins, Andrea Rielli, Alexander R Cruden, Hilke J Dalstra, Siobhan A. Wilson, Chenghao Li, Jens BaumgartnerAbstract:Abstract The world’s major source of iron Ore is hosted in Precambrian banded iron formations. These chemical (meta-) sedimentary rocks are composed of alternating laminae of iron oxide minerals and chert. Despite the economic significance of high-grade iron Ore Deposits, controversy persists after decades of research on how banded iron formations became upgraded to form iron Ore. The fundamental requirement for iron Ore formation is the removal of vast amounts of chert coupled with an increased concentration of iron oxide minerals. Here, we assess the fate of colloidal hematite inclusions encapsulated in chert after quartz dissolution and examine their role in the formation of hematite Ore. We have analysed hematite Ores from the Hamersley Province (Australia) using a combination of petrography, high-resolution electron microscopy and X-ray diffraction. These techniques reveal the presence of abundant nano and microscale hematite particles that we suggest form the building blocks of larger hematite crystals within the iron Ore. Our textural observations indicate that hematite colloids that were previously encapsulated inside the microcrystalline quartz grains in chert layers are released during quartz dissolution, and subsequently reassemble in a self-similar fashion to from new microplaty hematite crystals via non-classical crystallisation pathways. Progressive growth and fusion leads to the transformation of hematite microplates into hematite bands, which resemble pre-existing iron oxide laminae of banded iron formations. In contrast to previous models, we observe the direct transformation of banded iron formations to microplaty hematite and have not found evidence that significant amounts of hematite formed through metamorphism of goethite or that intermediate carbonate minerals were involved during the upgrading of banded iron formations to pure hematite Ore. Given the strong evidence for hypogene fluids found in many Deposits, we have also assessed the role that such warm, highly saline fluids may have played during the evolution of iron Ore. Using insights from crystal chemistry we conclude that fluid infiltration impacts many aspects of iron Ore formation by controlling hematite colloid liberation and aggregation, and finally controlling the transformation of the colloids into macroscopic crystals of hematite via non-classical crystallisation mechanisms. Our study underlines the significance of hypogene fluids in the upgrading of banded iron formation to iron Ore, however, we suggest that their influence was mainly passive as hematite was not precipitated directly from these fluids.
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the role of deformation in the formation of banded iron formation hosted high grade iron Ore Deposits hamersley province australia
Precambrian Research, 2017Co-Authors: Mathias S Egglseder, Alexander R Cruden, Hilke J Dalstra, Leigh NicholasAbstract:Abstract The Hamersley Province (Western Australia) hosts some of the world’s largest iron Ore Deposits but despite decades of research, their genesis is still extensively debated. Many iron Ore Deposits are hosted in complexly deformed Archean to Paleoproterozoic banded iron formations, comprising thin chert and iron oxide bands interlayered with silicate-rich shales and carbonates. Current iron Ore genesis models have identified a strong structural control on Ore formation linked to extensive hypogene and supergene fluid circulation along fault structures. These fluid pathways facilitate the removal of vast amounts of gangue minerals, leading to enrichment of the iron oxide residue to iron Ore. However, the evolution of the associated structures has not yet been considered as a key element in Ore genesis. Here we show through multiscale structural analyses that deformation not only forms suitable fluid channels, but that folding and shearing also result in significant synkinematic removal of gangue minerals. Our multidisciplinary investigation of the structural evolution of the Mount Tom Price deposit combines microtectonic, field geology and 3D implicit modelling techniques to establish a link between deformation structures at various scales. Microscale shear bands and outcrop-scale asymmetric parasitic folds share striking similarities in their evolution and their controlling mechanisms. Both features record substantial non-coaxial deformation accompanied by volume changes due to stress-induced silica remobilisation. The closely spaced layering of rheologically different lithologies within Hamersley Province strata plays a crucial role in complex multilayer deformation, which resulted in extensive strain partitioning. Our study suggests that deformation was of major significance in the upgrading of banded iron formation to iron Ore and was active from the early stages of banded iron formation during diagenesis. Deformation structures also established a micro- to deposit-scale lateral and vertical fluid network, which enabled infiltration by hypogene and supergene fluids during or after deformation. These new insights have important implications for iron Ore genesis models, structural applications in the mine environment, and for understanding complex multilayer deformation with volume loss.
Leigh Nicholas - One of the best experts on this subject based on the ideXlab platform.
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the role of deformation in the formation of banded iron formation hosted high grade iron Ore Deposits hamersley province australia
Precambrian Research, 2017Co-Authors: Mathias S Egglseder, Alexander R Cruden, Hilke J Dalstra, Leigh NicholasAbstract:Abstract The Hamersley Province (Western Australia) hosts some of the world’s largest iron Ore Deposits but despite decades of research, their genesis is still extensively debated. Many iron Ore Deposits are hosted in complexly deformed Archean to Paleoproterozoic banded iron formations, comprising thin chert and iron oxide bands interlayered with silicate-rich shales and carbonates. Current iron Ore genesis models have identified a strong structural control on Ore formation linked to extensive hypogene and supergene fluid circulation along fault structures. These fluid pathways facilitate the removal of vast amounts of gangue minerals, leading to enrichment of the iron oxide residue to iron Ore. However, the evolution of the associated structures has not yet been considered as a key element in Ore genesis. Here we show through multiscale structural analyses that deformation not only forms suitable fluid channels, but that folding and shearing also result in significant synkinematic removal of gangue minerals. Our multidisciplinary investigation of the structural evolution of the Mount Tom Price deposit combines microtectonic, field geology and 3D implicit modelling techniques to establish a link between deformation structures at various scales. Microscale shear bands and outcrop-scale asymmetric parasitic folds share striking similarities in their evolution and their controlling mechanisms. Both features record substantial non-coaxial deformation accompanied by volume changes due to stress-induced silica remobilisation. The closely spaced layering of rheologically different lithologies within Hamersley Province strata plays a crucial role in complex multilayer deformation, which resulted in extensive strain partitioning. Our study suggests that deformation was of major significance in the upgrading of banded iron formation to iron Ore and was active from the early stages of banded iron formation during diagenesis. Deformation structures also established a micro- to deposit-scale lateral and vertical fluid network, which enabled infiltration by hypogene and supergene fluids during or after deformation. These new insights have important implications for iron Ore genesis models, structural applications in the mine environment, and for understanding complex multilayer deformation with volume loss.
