Trace elements in black and oil shales

Shpirt, M. Ya.; Пунанова, С. А.; Strizhakova, Yu. A.

doi:10.3103/s0361521907020115

Cited by 19 publications

(4 citation statements)

References 4 publications

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“…The metals initially concentrate in black muds on the sea floor by desorption from clays, followed by reduction and adsorption, forming organometallic bonds with particular organic (humic and fulvic) compounds (e.g., Vilor, 1983;Kribek, 1991;Zhang et al, 1995;Nekrasov, 1996;Wood, 1996;Hu et al, 2000, Shpirt et al, 2007Fig. 6A).…”

Section: Why Are Black Shales Enriched In Au and As?mentioning

confidence: 99%

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Large¹,

Bull²,

2011

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This paper presents evidence and arguments that carbonaceous sedimentary rocks were a source for Au and As in sediment-hosted orogenic and Carlin-type gold deposits and develops a corresponding genetic model. In this two-stage basin-scale model, gold and arsenic are introduced early into black shale and turbidite basins during sedimentation and diagenesis (stage 1) and concentrated to ore grades by later hydrothermal, structural, or magmatic processes (stage 2). In reduced continental margin basin settings, organic matter, sedimented under anoxic to euxinic conditions, immobilizes and concentrates gold, arsenic, and a range of trace elements (particularly V, Ni, Se, Ag, Zn, Mo, Cu, U) present in marine bottom waters, into fine-grained black mudstone and siltstone of slope and basin facies. During early diagenesis, gold and certain other trace elements (Ni, Se, Te, Ag, Mo, Cu, ±PGE) are preferentially partitioned into arsenian pyrite that grows in the muds. These processes produce regionally extensive black shale and turbidite sequences enriched in syngenetic gold and arsenic, commonly from 5 to 100 ppb Au and 10 to 200 ppm As. Rare organic-and sulfide-rich metalliferous black shales may contain up to 1 to 2 ppm Au and over 1,000 ppm As, present as refractory gold in arsenian pyrite and nanoparticles of free gold. During late diagenesis and early metamorphism (stage 2) the diagenetic arsenian pyrite is recrystallized to form coarser grained pyrite generations, and the organic matter is cooked to bitumen. Under higher grade metamorphism (lower greenschist facies and above) arsenian pyrite in carbonaceous shales is converted to pyrrhotite. These processes release gold, arsenic, sulfur and other elements (Sb, Te, Cu, Zn, Mo, Bi, Tl, and Pb) from the source rocks to become concentrated by hydrothermal processes, locally to produce gold ores, in structural sites such as fold hinge zones, shear or breccia zones within or above the black shale sequence. LA-ICP-MS analyses of diagenetic pyrite in carbonaceous sediments, both associated and not associated with gold deposits, suggests that invisible gold contents of greater than 250 ppb in diagenetic pyrite, are indicative of carbonaceous shale source rocks with the potential to produce economic gold deposits. Application of this sedimentary source-rock model enables a systematic exploration approach for sediment-hosted gold deposits, based on the distribution, composition and structure of carbonaceous shale sequences and their contained diagenetic pyrite.

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Section: Why Are Black Shales Enriched In Au and As?mentioning

confidence: 99%

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Large¹,

Bull²,

2011

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“…The Th/U ratio in shale can reflect the weathering intensity in the source area. ,,,,, In most cases, weathering and sedimentary recycling under oxidizing conditions typically result in oxidation of U 4+ to U 6+ , with the latter being more soluble . Th/U is typically about 3.5–4.0 in the most upper crustal rocks .…”

Section: Resultsmentioning

confidence: 99%

Sedimentary Model of Coal and Shale in the Paleogene Lijiaya Formation of the Huangxian Basin: Insight from Petrological and Geochemical Characteristics of Coal and Shale

Wang

et al. 2019

Energy Fuels

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Paleogene Huangxian Basin which lies in Eastern China contains deposits of many types of coal and shale associations. The sedimentary models of coal and shale associations are very important to explore the coal and shales. However, whether the transgression affected the lithofacies and geochemical characteristics of coal and shale in the Paleogene Huangxian Basin in eastern China has not been reported in detail, which is important to construct the sedimentary models. In this study, petrological and geochemical methods are used to comprehensively analyze the mineral composition, contents of major and trace elements, and distribution characteristics of geochemical parameters of coal and shale in Huangxian Basin. The results show that coal and shale have different macerals. The study of typical geochemical parameters (Mn/Ti, K2O/Na2O, Sr/Ba, and Th/U) shows that the no. 1 coal seam (CB1) and no. 4 coal seam (CB4) are least affected by seawater, while the no. 1-3 coal seam (CB1-3) is affected by seawater to some extent. Shale 1-3 (S1-3), shale 2 (S2), and shale 4 (S4) are affected by seawater, while shale 1 (S1) is little affected by seawater. In order to discuss the sedimentary model of coal and shale, the tectonic background, provenance, paleoclimate, and fault movement of Huangxian basin are analyzed. The results show that the basin is located at the continental island arc and the active continental margin. Transgression and tectonic movement affect the input of terrigenous debris. The paleoclimate during coal formation was warmer and wetter, while shale was cooler and drier. During basin subsidence, CB4–S4 and CB1–S2–S1 combinations were basically formed under the influence of transgression driven by paleoclimate change. The combination of S1-3 and CB1-3 was formed in a stable freshwater lacustrine environment, followed by transgression.

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“…The first group of elements is a typical sulphide mineral association. All these elements may be associated with Lower Ordovician (Tremadocian) Dictyonema shale (Dictyonema argillite), which is characterized by a high sulphide content (Petersell, 1997;Shpirt et al, 2007). The Dictyonema argillite contribution to the soils in the areas, where it outcrops (mainly near the Baltic Klint) and where the shales are exposed as a result of opencast mining of phosphorite in Maardu, are responsible for the soil contamination.…”

Section: Enrichment Indices (Ei)mentioning

confidence: 99%

Urban Geochemistry of Tallinn (Estonia): Major and Trace‐Elements Distribution in Topsoil

Bityukova

Birke

2011

Mapping the Chemical Environment of Urban Areas

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Trace elements in black and oil shales

Cited by 19 publications

References 4 publications

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Sedimentary Model of Coal and Shale in the Paleogene Lijiaya Formation of the Huangxian Basin: Insight from Petrological and Geochemical Characteristics of Coal and Shale

Urban Geochemistry of Tallinn (Estonia): Major and Trace‐Elements Distribution in Topsoil

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