Ammonium geochemistry in mineral exploration—a comparison of results from the American cordilleras and the southwest Pacific

Ridgway, J.; Appleton, J.D.; Levinson, A. A.

doi:10.1016/0883-2927(90)90022-w

Cited by 34 publications

(20 citation statements)

References 45 publications

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“…The source of the introduced ammonium is not known. The most probable source of ammonium in other examples of hydrothermal enrichment is organic-rich sedimentary country rock (Cooper and Bradley, 1990;Ridgway et al, 1990;Hall et al, 1991). However, the country rocks surrounding the Rosses complex are themselves granitic, and therefore unlikely to be ammonium-rich.…”

Section: Discussionmentioning

confidence: 99%

“…The ammonium content of granitic magmas is therefore of considerable petrogenetic interest. However, the ammonium ion is very easily mobilised by hydrothermal activity (Krohn and Altaner, 1987;Ridgway et al, 1990;Hall et al, 1991), andin a granite that has undergone hydrothermal alteration it may be difficult to distinguish primary ammonium from secondary ammonium. Because ammonium is an important constituent of hydrothermal systems, but only a trace constituent of igneous rocks, the ammonium content of the latter may be significantly modified by a degree of alteration which is too small to have a noticeable effect on the major element chemistry of the rock.…”

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confidence: 99%

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The influence of secondary alteration on the ammonium content of granites, exemplified by the Rosses complex of Donegal

Hall

1993

Mineral. mag.

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Ammonium analyses of representative rocks from the Rosses granite complex (Ireland) and their constituent mineral show that any variation of magmatic origin has been completely obscured by pervasive hydrothermal alteration. The altered rocks are strongly enriched in the ammonium ion, most of which is held by chloritized biotite and sericitized plagioclase. The present ammonium content of the Rosses granites averages 13 ppm, but the original ammonium content of the magmas is estimated to have been less than 5 ppm. Potassium feldspars may preserve a better record of the original magmatic ammonium content than the whole rocks or the biotites.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The influence of secondary alteration on the ammonium content of granites, exemplified by the Rosses complex of Donegal

Hall

1993

Mineral. mag.

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“…Recent literature on the geochemistry of ammonium (NH4 § has focused on the potential utility of fixed-NH4 as a geochemical indicator of hydrothermal ore deposits (Sterne et al, 1984;Kydd and Levinson, 1986;Williams et aL, 1987;Ridgeway et aL, 1990), or as a tracer hydrocarbon migration pathways in a burial diagenetic setting (Williams et aL, 1989). Hydrothermal ore deposits may be accompanied by increased concentrations of fixed-NH4 in host rock minerals resulting from the breakdown of organic matter.…”

Section: Introductionmentioning

confidence: 99%

“…Throughout diagenesis, NH4 § may be incorporated in clay minerals by adsorption and ion exchange, but more importantly by substitution for K § in authigenic minerals such as illite, feldspar, or zeolite. Published reports of this coupled organic-inorganic geochemical process have identified temperature, fluid chemistry, mineralogy and nitrogenproducing potential of the organic matter as the chief variables influencing the magnitude of the observed NH4 + geochemical anomalies (Williams et aL, 1989;Ridgeway et aL, 1990;Daniels and Altaner, 1990). Fixed-NH4 is structurally bound in silicates and is not easily released or exchanged under normal diagenetic conditions (Keeney and Nelson, 1982).…”

Section: Introductionmentioning

confidence: 99%

Ammonium Substitution in Illite During Maturation of Organic Matter

Williams

Ferrell

1991

Clays and clay miner.

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Abstract--Pierre shale samples from a thin stratigraphic zone within the contact aureole of the lamprophyric Walsen dike record changes due to thermal effects that are not influenced by detrital differences. Analyses of fixed-NH4, mineralogy, and Rock-Eval pyrolysis indicators of organic matter maturity provide new insights on the fixation process. Fixed-NH4 increases with the quantity of authigenic iUite formed from illite/smectite, but the maximum fixation per unit of illite formed occurs within the "oil window" where thermal breakdown of organic matter is rapid. Extrapolation of these results to the burial diagenetic regime supports the potential use of fixed-NH4 as an indicator of organic maturity and hydrocarbon migration pathways:

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“…Recent research has revealed that geological nitrogen has an important role in geological problems such as lithogeochemical explorations (Ridgway et al 1990;Glasmacher et al 2003), biogeochemical implications (Boyd 2001;Holloway & Dahlgren 2002), environmental studies (Crews et al 2001), and petrological investigations (Honma & Itihara 1981;Hall 1999).…”

Section: Introductionmentioning

confidence: 99%

The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)

Ahadnejad¹,

Hirt²,

Valizadeh³

et al. 2011

Geologica Carpathica

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Abstract:The ammonium (NH 4 + ) contents of the Malayer area (Western Iran) have been determined by using the colorimetric method on 26 samples from igneous and metamorphic rocks. This is the first analysis of the ammonium contents of Iranian metamorphic and igneous rocks. The average ammonium content of metamorphic rocks decreases from low-grade to high-grade metamorphic rocks (in ppm): slate 580, phyllite 515, andalusite schist 242. In the case of igneous rocks, it decreases from felsic to mafic igneous types (in ppm): granites 39, monzonite 20, diorite 17, gabbro 10. Altered granitic rocks show enrichment in NH 4 + (mean 61 ppm). The high concentration of ammonium in Malayer granites may indicate metasedimentary rocks as protoliths rather than meta-igneous rocks. These granitic rocks (S-types) have high K-bearing rock-forming minerals such as biotite, muscovite and K-feldspar which their potassium could substitute with ammonium. In addition, the high ammonium content of metasediments is probably due to inheritance of nitrogen from organic matter in the original sediments. The hydrothermally altered samples of granitic rocks show highly enrichment of ammonium suggesting external sources which intruded additional content by either interaction with metasedimentary country rocks or meteoritic solutions.

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Ammonium geochemistry in mineral exploration—a comparison of results from the American cordilleras and the southwest Pacific

Cited by 34 publications

References 45 publications

The influence of secondary alteration on the ammonium content of granites, exemplified by the Rosses complex of Donegal

The influence of secondary alteration on the ammonium content of granites, exemplified by the Rosses complex of Donegal

Ammonium Substitution in Illite During Maturation of Organic Matter

The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)

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