Quantitative Mineralogy from Infrared Spectroscopic Data. II. Three-Dimensional Mineralogical Characterization of the Rocklea Channel Iron Deposit, Western Australia

Haest, Maarten; Cudahy, Thomas; Laukamp, Carsten; Gregory, Sean

doi:10.2113/econgeo.107.2.229

Cited by 59 publications

(36 citation statements)

References 22 publications

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“…However, the 2200D index is also sensitive to changes in dioctahedral mineral composition with kaolinite generating a lower response while white mica generates a higher response. It is also complicated by the nature of scattering interactions with other mineral grains, whether they be opaque phases such as graphite [74] or transparent ones such as quartz [75,76].…”

Section: Aster Spectral Mineral Indicesmentioning

confidence: 99%

“…These show a narrow low centered near Sites 55 and 56 (Figure 5b,c), which is coincident with the zone poor in (quartz) sand size material (Figure 3c). This association helps to explain this apparent 2200D low as the lesser amount of optically-transparent quartz grains reduces the overall optical thickness, resulting in less opportunity for electromagnetic radiation to interact with clay mineral particles [75,76]. This optical transparency effect also helps explain why the quartz-rich dune-fields ( Figure 5a) have moderate to high 2200D values (warmer tones) even though they generally contain less clay mineral content compared with loess ( Figure 3b,e and Figure 5b,c).…”

Section: Al-clay Content Indexmentioning

confidence: 99%

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Satellite ASTER Mineral Mapping the Provenance of the Loess Used by the Ming to Build their Earthen Great Wall

Cudahy¹,

Shi

Novikova³

et al. 2020

Remote Sensing

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The earthen border wall (Great Wall) built by the Ming is largely made of wind-blown loess. However, does the composition of this loess change along the length of the wall in response to variations in regional sediment transport pathways and impacting on the wall’s erosional durability? To date, defining these sediment transport pathways has been a challenge because of the paucity of spatially-comprehensive, compositional information. Here, we show that satellite ASTER mineral maps, combined with field sample measurements along a 1200 km section of the Ming’s earthen wall, reveal both the compositional heterogeneity of loess as well as the complexity of the sediment transport pathways of individual loess components, including: (i) quartz sand from Cretaceous sandstones in the Gobi Desert; (ii) gypsum from evaporative lakes in the Tengger Desert; (iii) kaolinite from Devonian Molasse in the Qilian Shan; and (iv) chlorite and muscovite from meta-volcanic rocks exposed across the Alashan Block. Sediment transport pathways involve a combination of colluvial, aeolian and fluvial (ephemeral and permanent) processes shaped by the topography. ASTER enabled mapping of compositional gradients related to two pathways, namely: (i) quartz sand driven by aeolian saltation in concert with the Yellow River; and (ii) clay and fine silt travelling large distances (>500 km) by long-term wind suspension. The most intact section of wall is found along the Hexi Corridor, which is poor in quartz sand and rich in (kaolinitic) clay and fine-silt, driven by wind-shielding by the Alashan Block. We also found evidence that the Ming: (i) mined loess from close by the wall (<1 km); (ii) targeted loess richer in finer fractions; and (iii) routinely applied a Ca-rich additive (probably lime).

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Section: Aster Spectral Mineral Indicesmentioning

confidence: 99%

Section: Al-clay Content Indexmentioning

confidence: 99%

Satellite ASTER Mineral Mapping the Provenance of the Loess Used by the Ming to Build their Earthen Great Wall

Cudahy¹,

Shi

Novikova³

et al. 2020

Remote Sensing

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“…Calcrete and dolocrete duricrusts developed within channel and valley sediments following a shift to aridity and slightly cooler conditions in the Late Miocene (Barnett and Commander, 1985;Humphreys, 2001;Kneeshaw and Morris, 2014). Calcrete has been reported overlying channel iron deposits, particularly within upstream constrictions in strike valleys and within the Oakover Formation in the northeast Pilbara (Morris and Ramanaidou, 2007;Kneeshaw and Morris, 2014), although mineralogical data suggest that many of the reported 'calcretes' are dolomitic (Barnett, 1980;Barnett and Commander, 1985;Hewson et al, 2006;Haest et al, 2012). Dolocrete also occurs throughout the Fortescue Valley palaeodrainage, within the Millstream Formation of the Western Fortescue Valley (Barnett and Commander, 1985) and within the Fortescue Marsh to the east (Mather et al, 2018).…”

Section: Geological and Geomorphological Contextmentioning

confidence: 99%

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi‐arid Hamersley Basin, northwest Australia

Mather

Nash

Dogramaci

et al. 2019

Earth Surf Processes Landf

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Groundwater dolocretes may exert an important geomorphic control on landscape evolution within sub‐humid to arid regions. However, the geomorphic and hydrogeological settings of dolocrete remain poorly described. The hydrochemical conditions of dolomite precipitation in groundwater environments are also not well known. Classic models of dolocrete formation explain dolomite precipitation from highly evolved groundwaters at the terminus of major drainage but do not explain dolocrete distributed in regionally elevated landscapes, upgradient of major drainage. This study investigated the mineralogy, micromorphology and stable carbon and oxygen isotope compositions of three dolocrete profiles within a regionally elevated sub‐basin of the Hamersley Ranges in the Pilbara region of northwest Australia. We sought to establish the environmental and hydrochemical conditions and present a model for dolocrete formation. We found that dolocrete formed within zones of emerging groundwater under saline‐evaporitic conditions within internally draining sub‐basins, most likely during the Late Miocene and Pliocene. Saline‐evaporitic conditions were indicated by: (i) the mineralogy, dominated by dolomite, palygorskite and smectite; (ii) desiccation features and the presence of phreatic and vadose cements, indicative of a shallow fluctuating water table, and; (iii) dolomite δ18O values (median = –5.88 ‰). Dolomite precipitation was promoted by evaporation and carbon dioxide degassing from shallow magnesium (Mg)‐rich groundwater. These factors appear to have been the major drivers of dolocrete development without a requirement for significant down‐dip hydrochemical modification. Primary dolomite precipitation was possible due to the presence of microbial extracellular polymeric substances (EPS). EPS provided negatively charged nucleation sites, which bound Mg2+, overcoming kinetic effects. High microbial activity within groundwater systems suggest these processes may be important for dolocrete formation worldwide and that groundwater dolocretes may be more pervasive in landscapes than currently recognized. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

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“…Mineralogical and chemical data are needed for optimizing the mining process. At present, these data are mostly obtained by using a single technique, like XRF scanner or hyperspectral imaging . A combined, multitechnique analytical characterization of drill cores can be the solution for speeding up exploration and mining, thus reducing mining costs and environmental impact .…”

Section: Introductionmentioning

confidence: 99%

Mineralogical investigations using XRD, XRF, and Raman spectroscopy in a combined approach

Secchi

Zanatta

Borovin

et al. 2018

J Raman Spectroscopy

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The identification of mineralogical phases in drill cores is one of the most challenging tasks in the mining activity in view of an efficient metal extraction. This process requires the analytical characterization of large volumes of material to obtain a complete set of data in a minimum of time. None of the commonly used methods in mineralogical analyses, such as IR‐based techniques, X‐rays fluorescence, and hyperspectral imaging, is capable to provide a fully satisfactory response for several reasons, the main one being the complexity of the ores. Moreover, the characterization is often conducted in remote laboratories and only on selected samples to limit the time waste. A possible alternative solution requires a multianalytical approach exploiting on‐field techniques. This strategy is currently being developed within SOLSA, a joint EU H2020 project, and consists of an automatic expert system coupling sonic drilling, imaging, profilometer, hyperspectral cameras, and a combination of Raman spectroscopy, X‐rays fluorescence, and X‐rays diffraction. In this work, the principles on which this cooperative approach is based are discussed, with application to two specific test samples, showing the potential and novelty of the method. In particular, a case is considered in which the sample characterization by the separate use of a single technique fails, whereas the combination of the three analyses (Raman spectroscopy, X‐rays fluorescence, and X‐rays diffraction) works even if the system is very complex.

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Quantitative Mineralogy from Infrared Spectroscopic Data. II. Three-Dimensional Mineralogical Characterization of the Rocklea Channel Iron Deposit, Western Australia

Cited by 59 publications

References 22 publications

Satellite ASTER Mineral Mapping the Provenance of the Loess Used by the Ming to Build their Earthen Great Wall

Satellite ASTER Mineral Mapping the Provenance of the Loess Used by the Ming to Build their Earthen Great Wall

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi‐arid Hamersley Basin, northwest Australia

Mineralogical investigations using XRD, XRF, and Raman spectroscopy in a combined approach

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