Mississippi Valley-type lead–zinc deposits through geological time: implications from recent age-dating research

Leach, D. L.; Bradley, Dwight C.; Lewchuk, Michael T.; Symons, D. T. A.; Marsily, Ghislain de; Brannon, J. C.

doi:10.1007/s001260100208

Cited by 255 publications

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“…Based on the examples from north America (Betkhe and Marshak, 1990;Leach et al, 2001;Gregg, 2004), this kind of massive fluidflow within the fold and thrust belt could have reached also the foreland. In the southern Apennines, the foreland of the Miocene fold and thrust belt was represented by shallow-water carbonates of the Apulian Platform.…”

Section: Discussionmentioning

confidence: 99%

Late Dolomitization in Basinal Limestones of the Southern Apennines Fold and Thrust Belt (Italy)

Iannace

Gasparrini

Gabellone

et al. 2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Bois-Préau, 92852 Rueil-Malmaison Cedex -France e-mail: aleianna@unina.it -marta.gasparrini@ifpen.fr -tatyana.gabellone@unina.it -smazzoli@unina.it Résumé -Dolomitisation tardo-diagénétique dans les calcaires de bassins triassiques de l'Apennin Méridional (Italie) -Les carbonates pélagiques triassiques de l'Unité de Lagonegro, dans l'Apennin méridional hébergent des corps dolomitiques discordants. Ces dolomies montrent les structures typiques connues comme "zébra" ou dolomite "à selle". Dans cette note, on présente les résultats d'observations de terrains et pétrographiques et les données géochimiques obtenues sur trois affleurements. Les données de terrain indiquent que les structures de type "zébra" et bréchifiées sont contrôlées par la stratification très régulière des calcaires micritiques. La dolomitisation a comporté le remplacement du calcaire et de la précipitation de dolomite cristalline dans les vides sous un champ de contraintes extensionnelles. Les températures d'homogénéisation sont comprises entre 80 et 120 °C, avec un mode à (95 ± 10) °C. Après une correction de pression, elles indiquent une température maximale de formation de la dolomie d'environ 110-115 °C. Les températures de fusion de la glace indiquent une salinité comprise entre 2 et 6 wt% NaCl eq, avec une moyenne de 4.2 %. Les valeurs de δ 13 C sont comparables à celles de l'eau de mer triassique, tandis que les valeurs de δ 18 O sont fortement appauvries. Les valeurs du rapport 87 Sr/ 86 Sr sont au contraire plus élevées que celles estimées pour l'eau de mer triassique, mais comparables à celles du Miocène Moyen-Supérieur. Ces résultats indiquent une dolomitisation accomplie par des fluides relativement chauds avec une salinité voisine de celle de la mer et une composition isotopique comprise entre celle de l'eau de mer et celle de saumures de bassin. On propose que cette dolomitisation a été achevée par les eaux expulsées par les formations qui entourent les carbonates pélagiques triassiques ou celles du mélange sous-jacent. L'intégration des données sur l'histoire thermique et de la déformation indique, si l'on assume un équilibre thermique avec les roches encaissantes, que ce phénomène ait eu lieu après le pic d'enfouissement pendant les premiers stades de l'exhumation. Enfin, puisque les dolomies sont assez répandues dans la région, il est bien possible qu'une importante circulation de fluides ait intéressé l'entier fold-and thrust-belt pendant la déformation, y compris les unités de la Plate-forme Apulienne, qui héberge des importants réservoirs d'hydrocarbures. Abstract

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Section: Discussionmentioning

confidence: 99%

Late Dolomitization in Basinal Limestones of the Southern Apennines Fold and Thrust Belt (Italy)

Iannace

Gasparrini

Gabellone

et al. 2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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“…Symons et al 1996;Leach et al 2001;Zegers et al 2003). This approach is based on the hypothesis that the mineralizing fluids cause precipitation of magnetic phases (magnetite and pyrrhotite); see Symons et al (1996) for a summary of the palaeomagnetic dating approach and for the results from a number of MVT deposits.…”

Section: Mineralizing Fluidsmentioning

confidence: 99%

Remagnetization and chemical alteration of sedimentary rocks

Elmore

Muxworthy

Aldana

2012

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Chemical remagnetization is a very common phenomenon in sedimentary rocks and developing a greater understanding of the mechanisms has several benefits. Acquisition of a secondary magnetization is usually tangible evidence of a diagenetic event that can be dated by isolation of the chemical remanent magnetization and comparison of the pole position to the apparent polar wander path. This can be important because diagenetic investigations are frequently limited by the difficulty in constraining the time frames in which most past events have occurred. Remagnetization can commonly obscure a primary magnetization; developing a better understanding of remagnetization could improve our ability to uncover primary magnetizations. Many chemical remagnetization mechanisms have been proposed, including those associated with chemical alteration by a number of different fluids (orogenic, basinal and hydrocarbons), burial diagenetic processes (clay diagenesis and maturation of organic matter) or other processes. This paper summarizes our current knowledge of these chemical remagnetization mechanisms, with a focus on examples where there is a connection with chemical alteration.

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“…For instance the MVT deposits encompass a wide range of ore styles (subtypes like Irish-and vein-type MVT) depending on the geological features (lithology and structures) that control fluid migration and sulphide-forming processes [54]. The deposits formed by similar depositional processes from migrating dense basinal metalliferous brines and with the Pb derived from a crustal source [56]. The ore fluids in all sediment-hosted Pb-Zn deposits share similar low temperatures (50-250 °C) and medium to high salinities (10-30 eq.…”

Section: Is the Fracture-controlled Zn-pb Mineralisation In The Lsod mentioning

confidence: 99%

Zn-Pb Ores of Mississippi Valley Type in the Lycksele-Storuman District, Northern Sweden: A Possible Rift-Related Cambrian Mineralisation Event

et al. 2012

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Abstract:The epigenetic Zn-Pb deposits in the Lycksele-Storuman ore district, northern Sweden, are hosted by Paleoproterozoic basement near the margin of the Caledonian mountains. A paleogeographic reconstruction suggests that platform sediments, including Cambrian shales, overlaid the mineralised basement. The mineralisation type, containing sphalerite, galena, calcite and fluorite, is confined to veins and breccias and interpreted to be of Mississippi Valley Type (MVT) style. There is no appreciable wall rock alteration. Fluid inclusion work reveals coexisting aqueous and hydrocarbon fluids. Ore deposition is interpreted to have occurred during mixing of two fluids; a cool (<70 °C) brine with a salinity of 30 eq. mass% CaCl 2 and a hot (~200 °C) brine with about 18 eq. mass% CaCl 2 . The mixing led to complex Sr isotope systematics in the analysed minerals. A tentative sphalerite Rb-Sr isochron age of a 534 ± 13 Ma probably dates mineralisation. The isotope systematics of Pb and Nd are less complex and both elements were essentially leached OPEN ACCESSMinerals 2012, 1 170 from basement rocks and transported by the hot fluid. Ore formation is considered to have taken place during rifting, related to the opening of the Iapetus Ocean.

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Mississippi Valley-type lead–zinc deposits through geological time: implications from recent age-dating research

Cited by 255 publications

References 0 publications

Late Dolomitization in Basinal Limestones of the Southern Apennines Fold and Thrust Belt (Italy)

Late Dolomitization in Basinal Limestones of the Southern Apennines Fold and Thrust Belt (Italy)

Remagnetization and chemical alteration of sedimentary rocks

Zn-Pb Ores of Mississippi Valley Type in the Lycksele-Storuman District, Northern Sweden: A Possible Rift-Related Cambrian Mineralisation Event

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