Miocene chemoherms of the northern Apennines, Italy

Conti, Stefano; Fontana, Daniela

doi:10.1130/0091-7613(1999)027<0927:mcotna>2.3.co;2

Cited by 46 publications

(26 citation statements)

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“…This scenario of hydrate-derived gas seepage caused by accretionary prism formation in convergent margin settings is analogous to the recent situation at the Cascadia margin oVshore Oregon (see Ritger et al 1987;Bohrmann et al 1998;Suess et al 1999;Teichert et al 2005). The best ancient counterpart of the examined palaeoseep is found in the northern Apennines, where Miocene seep carbonates of similar lithological features were formed in an analogous geotectonic and sedimentary environment (see Conti and Fontana 1999, 2002.…”

Section: Gas Hydrate Decomposition and Methane Migrationmentioning

confidence: 83%

Oligocene cold-seep carbonates from the Carpathians and their inferred relation to gas hydrates

Bojanowski

2007

Facies

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The Krosno Formation of the Outer Carpathians is composed of synorogenic deposits laid down in the Silesian foredeep basin in front of an accretionary prism. The Oligocene shales of the Krosno Formation from Jwiatkowa Wielka (the Polish part of the Outer Carpathians) contain numerous authigenic carbonate rocks: concretions, a laminated limestone bed, and a carbonate build-up consisting of intraformational breccia. The application of stable carbon isotope analysis revealed that the formation of these carbonates was induced by methane oxidation. The presence of fossilized giant Beggiatoa-like Wlaments and large quantities of framboidal pyrite indicate that methane oxidation was microbially driven and coupled with sulfate reduction. A model of origin of these coldseep carbonates in relation to hydrocarbon seepage is herein presented. Characteristic druses with clast-like appearance are thought to inherit their outlines from former clasts of gas hydrate that had been present within the build-up. It is proposed that thick gas hydrate deposits existed in the southern part of the Silesian basin at that time. This theory is consistent with regional, geotectonic, and palaeobathymetric data and provides a ready explanation of the major phenomena that have been recorded in the Krosno Formation.

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Section: Gas Hydrate Decomposition and Methane Migrationmentioning

confidence: 83%

Oligocene cold-seep carbonates from the Carpathians and their inferred relation to gas hydrates

Bojanowski

2007

Facies

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“…1a). In the Epiligurian satellite basins and the inner part of the foredeep, seep-carbonates are found within marly and clayey hemipelagites and fine-grained turbidites Vai, 1994: Cavagna et al, 1999;Conti and Fontana, 1999). In the foredeep, seep-carbonates occur in two different settings: -in pelitic intervals related to intrabasinal highs, with a lateral extent of 10e30 km, intercalated within the LanghianeSerravallian basin plain succession of the Mt.…”

Section: Geological Settingmentioning

confidence: 97%

“…In the Miocene of the northern Apennines, the abundance and extent of seep-carbonates in different tectonic-sedimentary settings, from foredeep to satellite basins (Clari et al, 1994;Terzi et al, 1994;Conti and Fontana, 1999;Taviani, 2001;, provide a rare opportunity to study the evolution of the seepage system, fluid migration paths, and in particular the tectonic and/or climatic controls on seepage. Part of these seep-carbonates, located atop intrabasinal highs and associated with sediment instability, commonly formed at the toe of the deformation front of the northern Apennine accretionary wedge.…”

Section: Introductionmentioning

confidence: 99%

Evidence of climatic control on hydrocarbon seepage in the Miocene of the northern Apennines: The case study of the Vicchio Marls

Fontana

Conti

Grillenzoni

et al. 2013

Marine and Petroleum Geology

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“…In this context, fossil chemoherms are important indicators of palaeoseep occurrences and their study can contribute to reconstruct processes and environments of carbonate precipitation. Thus, diagnostic compositional and sedimentological criteria for their identification are reported by various authors (Goedert and Squires 1990;Beauchamp and Savard 1992;Bitter et al 1992;Gaillard et al 1992;Kelly et al 1995;Kauffman et al 1996;Conti and Fontana 1999;Callender and Powell 1999). In addition, the morphology of carbonate precipitates and the associated brecciated structures can be used to infer the intensity and style of fluid expulsion, allowing differentiation between diffuse fluid flow and discrete-intense fluid venting (Campbell and Bottjer 1993;Orange et al 1999).…”

Section: Introductionmentioning

confidence: 95%

Sediment instability related to fluid venting in Miocene authigenic carbonate deposits of the northern Apennines (Italy)

Conti

Fontana

2002

Int J Earth Sci (Geol Rundsch)

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Chemosynthetic carbonates, identified by isotopic, palaeoecological and sedimentological features, are concentrated in middle-late Miocene satellite and foredeep deposits of the northern Apennines. Chemoherms in the foredeep are hosted in thick pelitic intervals, probably deposited in intrabasinal structural highs, which are entirely or partly involved in large slumps, in many cases associated with extrabasinal slides. Sediment textures in carbonates and in the enclosing foredeep pelitic sediments indicate a link between hydrocarbon-fluid venting, sediment deformation and mobilisation, and tectonics. The intensity and style of fluid release phases directly influenced chemoherm typology, and also determined overpressure conditions in low shear strength pelitic sediments, favouring sediment mobilisation and influencing slope instability, which widely affected the Apennine foredeep. Chemosynthetic carbonates are associated with sites of tectonically fractured and compressed sediments in the Apennine foredeep-thrust belt system, thus indicating a relation with the tectonic loading of the Apennine thrust-sheets, which favoured fluid expulsion along forerunner faults. Possible gas hydrate contributions to fluid expulsion processes are discussed, based on sediment textures compared with modern vent areas. Finally, sediment instability may have facilitated a large amount of fluid escape, thus stopping carbonate precipitation.

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Miocene chemoherms of the northern Apennines, Italy

Cited by 46 publications

References 0 publications

Oligocene cold-seep carbonates from the Carpathians and their inferred relation to gas hydrates

Oligocene cold-seep carbonates from the Carpathians and their inferred relation to gas hydrates

Evidence of climatic control on hydrocarbon seepage in the Miocene of the northern Apennines: The case study of the Vicchio Marls

Sediment instability related to fluid venting in Miocene authigenic carbonate deposits of the northern Apennines (Italy)

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