Analytical techniques for the separation and SEM identification of heavy minerals in mudrocks

Hanan, Mark A.; Totten, Matthew W.

doi:10.2110/jsr.66.1027

Cited by 11 publications

(7 citation statements)

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“…Following Hanan and Totten (1996), grain mineralogies were determined through chemical analyses by EDS and mineral shape, the latter obtained by back scattered electron imaging. Through EDS chemical analysis, it was possible to distinguish between pyroxenes (Fe-Mg pyroxenes, diopsides, titanaugites), amphiboles and oxides.…”

Section: Methodsmentioning

confidence: 99%

Early Miocene Antarctic glacial history: new insights from heavy mineral analysis from ANDRILL AND-2A drill core sediments

Iacoviello

Giorgetti

Memmi

et al. 2014

Int J Earth Sci (Geol Rundsch)

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The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL-SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6-20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected a variety of terrigenous lithologies. The heavy mineral assemblages of the lower 650-m-thick sedimentary succession were analyzed through SEM observations and SEM-EDS microanalyses on heavy mineral grains. The heavy mineral analysis shows that the sediments are a mix of detritus dominated by McMurdo Volcanic Group sources most likely located in the present-day Mount Morning area (Proto-Mount Morning) with minor contribution from Transantarctic Mountains source rocks located west of the drill site. The heavy mineral assemblages in Interval 1 indicate that between 20.2 and 20.1 Ma, the grounding line of the ice sheet advanced to a position near the present-day Mount Morning volcanic center. During deposition of Interval 2 (20.1-19.3 Ma), the ice sheet most likely experienced a dynamic behavior with interval of ice advance alternating with periods of ice retreat, while Interval 3 (19.3-18.7 Ma) records further retreat to open water conditions. A dynamic behavior is noted in Interval 4 (18.7-17.6 Ma) with a decreasing contribution of materials derived from the basalts of the Mount Morning volcanic center located to the south of the drill site and a consequent increasing contribution of materials derived from the Transantarctic Mountains to the west of the drill site.

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Section: Methodsmentioning

confidence: 99%

Early Miocene Antarctic glacial history: new insights from heavy mineral analysis from ANDRILL AND-2A drill core sediments

Iacoviello

Giorgetti

Memmi

et al. 2014

Int J Earth Sci (Geol Rundsch)

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“…Samples of siderite for stable-isotope analyses were gravimetrically separated and concentrated from the soil matrix at the Kansas Geological Survey after petrographic studies indicated that the concretionary masses of microcrystalline siderite were not large enough for microdrilling of mineral powders to generate d 13 C and d 18 O values. Thus, heavy-liquid separation of the dense mineral fraction (presumably mostly siderite) from five coal-tar-contaminated alluvial samples was based on a method described in Hanan and Totten (1996). Samples were lightly crushed in a glass mortar and pestle, loaded into 50 ml plastic centrifuge tubes, and then dispersed in 40 ml of lithium metatungstate (LMT)-a 2.95 g/cm 3 , water-soluble heavy liquid.…”

Section: Methodsmentioning

confidence: 99%

Micromorphology and Stable-Isotope Geochemistry of Historical Pedogenic Siderite Formed in PAH-Contaminated Alluvial Clay Soils, Tennessee, U.S.A.

Driese¹,

Ludvigson²,

Roberts³

et al. 2010

Journal of Sedimentary Research

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Alluvial clay soil samples from six boreholes advanced to depths of 400-450 cm (top of limestone bedrock) from the Chattanooga Coke Plant (CCP) site were examined micromorphologically and geochemically in order to determine if pedogenic siderite (FeCO 3) was present and whether siderite occurrence was related to organic contaminant distribution. Samples from shallow depths were generally more heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) than those at greater depth. The upper 1 m in most boreholes consisted of mixtures of anthropogenically remolded clay soil fill containing coal clinker, cinder grains, and limestone gravel; most layers of coarse fill were impregnated with creosote and coal tar. Most undisturbed soil (below 1 m depth) consisted of highly structured clays exhibiting fine subangular blocky ped structures, as well as redox-related features. Pedogenic siderite was abundant in the upper 2 m of most cores and in demonstrably historical (, 100 years old) soil matrices. Two morphologies were identified: (1) sphaerosiderite crystal spherulites ranging from 10 to 200 mm in diameter, and (2) coccoid siderite comprising grape-like ''clusters'' of crystals 5-20 mm in diameter. The siderite, formed in both macropores and within fine-grained clay matrices, indicates development of localized anaerobic, low-Eh conditions, possibly due to microbial degradation of organic contaminants. Stable-isotope compositions of the siderite have d 13 C values spanning over 25% (+7 to 218% VPDB) indicating fractionation of DIC by multiple microbial metabolic pathways, but with relatively constant d 18 O values (24.8 ± 0.66% VPDB) defining a meteoric sphaerosiderite line (MSL). Calculated isotope equilibrium water d 18 O values from pedogenic siderites at the CCP site are from 1 to 5 per mil lighter than the groundwater d 18 O values that we estimate for the site. If confirmed by field studies in progress, this observation might call for a reevaluation of low-temperature siderite-water 18 O fractionations. Investigations at the CCP site thus provide valuable information on the geochemical conditions under which siderite can form in modern soils, and thus insight on controls on siderite formation in ancient soils. SITE DESCRIPTION Coal coking operations were conducted at the Chattanooga Coke Plant (CCP) site, (formerly the Tennessee Products Site) located near

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“…Then heavy minerals from each sample were mounted onto a glass slide, carbon coated and viewed using a scanning electron microscope (Philips XL30 SEM) equipped with an energy dispersive Xray detection system (EDAX). Following the method proposed by Hanan and Totten (1996), we determined each mineral through semiquantitative chemical analyses. The grain morphology allows to establish the crystallinity versus glassy nature of the grains; the chemical analyses allows to determine the mineral composition, making it possible to refine the distinction among pyroxenes (Fe-Mg pyroxenes, diospide, Titanoaugites), amphiboles, oxides.…”

Section: Methodsmentioning

confidence: 99%

Provenance of Pleistocene sediments in the ANDRILL AND-1B drillcore: Clay and heavy mineral data

Giorgetti

Talarico

Sandroni³

et al. 2009

Global and Planetary Change

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a b s t r a c t a r t i c l e i n f o The cryosphere in the McMurdo Sound region has undergone significant modifications during the last 1 Ma. Consequently, the sedimentary sequences underlying the modern McMurdo Ice-Shelf provide geological data to reconstruct variations in transport and depositional mechanisms of terrigenous material due to variations in ice sheet extension, grounding line position and main ice-stream flow directions during glacial and interglacial periods. The present study aims to investigate the clay and heavy mineral assemblages of the late Pleistocene subglacial and glaciomarine sediments recovered during the ANDRILL-McMurdo Ice Shelf Project in Windless Bight (South of Ross Island). The analyses show that the sediments are a mix of detritus from the McMurdo Volcanic Group (MVG) and the Transantarctic Mountains (TAM) from the south and west. MVGderived minerals prevail with respect to TAM-derived minerals. The down-core mineralogical variations are determined by changes in the source rocks and the sedimentary processes. Sediments at the drill site are nourished by ice coming from the South which delivered rocks from the McMurdo Volcanic region; the enrichment of a TAM component in massive diamictites testifies that the ice sheet collected debris from the Transantarctic Mountains. When open marine conditions prevailed, only sediments from a local source (i.e. McMurdo volcanics) were deposited.

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Analytical techniques for the separation and SEM identification of heavy minerals in mudrocks

Cited by 11 publications

References 0 publications

Early Miocene Antarctic glacial history: new insights from heavy mineral analysis from ANDRILL AND-2A drill core sediments

Early Miocene Antarctic glacial history: new insights from heavy mineral analysis from ANDRILL AND-2A drill core sediments

Micromorphology and Stable-Isotope Geochemistry of Historical Pedogenic Siderite Formed in PAH-Contaminated Alluvial Clay Soils, Tennessee, U.S.A.

Provenance of Pleistocene sediments in the ANDRILL AND-1B drillcore: Clay and heavy mineral data

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