Abstract
Correlation and provenancing of sediments/sedimentary rocks can be achieved by several techniques; a common approach is through the identification and quantification of heavy minerals using a petrological microscope. This can be time consuming, the analysis of heavy minerals by inductively coupled plasma atomic emission spectroscopy offers a faster alternative, by determining key elements associated with specific heavy minerals. Here we outline a method for determining heavy mineral species though ICP-AES using high temperature fusion with a lithium metaborate flux to ensure complete dissolution of resistate minerals. The method was tested in a provenance study of desert sands from the United Arab Emirates. The results are compared with those derived from traditional optical microscopy. These show good agreement for minerals with specific geochemical signatures, whilst the overall geochemistry of the heavy mineral concentrate was diagnostic of potential sediment sources. This geochemical approach is capable of processing large numbers of samples rapidly and is advocated as a screening technique. A combination of geochemical and mineralogical data produced by these techniques provides a powerful diagnostic tool for studies of heavy mineral signatures in sediments frequently used in mineral reconnaissance, paleogeographic reconstruction and reservoir characterisation in the petroleum industry.
Highlights
Understanding the origin or provenance of sediments/sedimentary rocks is important in the reconstruction of sediment pathways and paleogeography (Garzanti et al, 2007 and Weltje and Eynatten, 2004), as a tool for mineral reconnaissance (Morton and Berge, 1995), or oil and gas reservoir characterisation (Averill, 2001)
Optical microscopy provides information on grain morphology, physico-chemical alteration and the accurate identification of individual heavy mineral species. Such detailed assessment of mineral concentrates can aid in assessing whether the heavy mineral component of a sediment has been altered through selective dissolution, diagenesis or preferential sorting during transportation (Andò et al, 2012)
In this paper we demonstrate the validity of a geochemical approach to heavy mineral provenance studies, by comparing the interpretation of geochemical data with results from the traditional optical microscopy
Summary
Understanding the origin or provenance of sediments/sedimentary rocks is important in the reconstruction of sediment pathways and paleogeography (Garzanti et al, 2007 and Weltje and Eynatten, 2004), as a tool for mineral reconnaissance (Morton and Berge, 1995), or oil and gas reservoir characterisation (Averill, 2001). The main advantage of analysing the heavy mineral fraction is to reduce the dilution from minerals such as quartz, feldspars, carbonate and clays that can typically constitute up to 99% of the sediment and are not generally provenance specific (Morton and Hallsworth, 1999). Optical microscopy provides information on grain morphology, physico-chemical alteration and the accurate identification of individual heavy mineral species. Such detailed assessment of mineral concentrates can aid in assessing whether the heavy mineral component of a sediment has been altered through selective dissolution, diagenesis or preferential sorting during transportation (Andò et al, 2012). Minerals excluded from the count include opaque minerals (e.g. magnetite, ilmenite), minerals that are potentially unrepresentative (carbonates, authigenic minerals) or minerals whose specific density is affected by inclusions of another mineral of greater density (magnetite, ilmenite, etc.) than that of the host mineral (Hounslow and Morton, 2004)
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