Biodetrital carbonates on the Adriatic continental shelf imprinted by oxidation of seeping hydrocarbons

Taviani, Marco; Franchi, Fulvio; Angeletti, Lorenzo; Correggiari, A.; Lopez-Correa, Matthias; Maselli, Vittorio; Mazzoli, Claudio; Peckmann, Jörn

doi:10.1016/j.marpetgeo.2015.03.015

Cited by 19 publications

(21 citation statements)

References 78 publications

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“…A geological origin is therefore explored here as the structures look like concretions formed by localised authigenic cementation of sediment (cf. Angeletti et al, 2015;Nyman et al, 2010;Wirsig et al, 2012). Our interpretations and conclusions while of obvious interest to geologists also have significance for archaeologists and even tourists who enjoy snorkelling.…”

Section: Introductionmentioning

confidence: 70%

“…Moreover, the linear distribution of the concretions, and their association with a low sea-bed ridge suggests the possible presence of a blind fault below the recent sea bed muds, which might be related to fluid flow. The pipe-like, disk and doughnut morphology and the size of the concretions is typical of authigenic carbonates associated with hydrocarbon-seeps seen both in modern seafloor and palaeo-settings (e.g., Angeletti et al, 2015;Kocherla et al 2015;Reitner et al, 2015). Pipe-like concretions, are considered by Reitner et al (2015) to be formed by micro seepage of hydrocarbon-rich fluids and slab-like morphologies have been related to more diffuse flows (Naehr et al, 2007;Suess 2014 The presence of pyrite indicates active sulphate reduction in the sediment throughout the cementation history.…”

Section: Interpretation Of Sedimentary Morphological and Isotopic Datamentioning

confidence: 91%

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Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos Island (Greece): Concretions not archaeological remains

Andrews

Stamatakis

Marca-Bell

et al. 2016

Marine and Petroleum Geology

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Section: Introductionmentioning

confidence: 70%

Section: Interpretation Of Sedimentary Morphological and Isotopic Datamentioning

confidence: 91%

Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos Island (Greece): Concretions not archaeological remains

Andrews

Stamatakis

Marca-Bell

et al. 2016

Marine and Petroleum Geology

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“…2) are characterized by abundant concretions, mainly consisting of calcite/aragonite and siderite (Table 1). Aragonite represents a typical precipitate at methane seeps where microbial activity induces the increase of alkalinity in pore solutions by AOM and the consequent precipitation of authigenic carbonates (e.g., Taviani, 2001;Peckmann and Thiel, 2004;Campbell et al, 2008;Taviani et al, 2015). At methane seeps, aragonite precipitation is thought to be favored by the presence of sulfate ions, which on the other hand inhibit dolomite precipitation (e.g., Magalhães et al, 2012;Zhang et al, 2012).…”

Section: Characterization Of Authigenic Mineralsmentioning

confidence: 99%

“…Precipitation of dolomite is indeed favored by low concentrations of sulfate (Magalhães et al, 2012) and therefore, it is unlikely to form together with aragonite or at present day conditions with up to 3918 mg L À1 of SO 4 2À in the bottom seawater (Table 8). Nevertheless, recent studies demonstrated how high sulfide concentration, rather than low sulfate, favors dolomite precipitation at sites of methane seepage (Zhang et al, 2012;Taviani et al, 2015). At times of intense seepage the SMTZ is pulled further upward through the subseafloor sediment and the sulfates in the shallow sediments are more efficiently consumed releasing Mg-ions.…”

Section: Characterization Of Authigenic Mineralsmentioning

confidence: 99%

“…In the western part of the central Mediterranean Sea, the Tyrrhenian Sea, evidences of fluid seepage are limited to the Adriatic Sea (Geletti et al, 2008), Strait of Sicily, Sardinian Margin (Dalla Valle and Gamberi, 2011) and Malta Plateau (Savini et al, 2009;Micallef et al, 2011;Taviani et al, 2013), mostly in the form of pockmarks, occasionally associated with methane-imprinted carbonates (Capozzi et al, 2012;Cangemi et al, 2010;Angeletti et al, 2015;Taviani et al, 2015). In the westernmost part of the Central Mediterranean Sea, the Tyrrhenian Sea, little evidence of past and present fluid circulation was found in the deep sea, except for the Paola Ridge, along the NW Calabrian margin (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Authigenic minerals from the Paola Ridge (southern Tyrrhenian Sea): Evidences of episodic methane seepage

Franchi

Rovere

Gamberi

et al. 2017

Marine and Petroleum Geology

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a b s t r a c tPaola Ridge, along the NW Calabrian margin (southern Tyrrhenian Sea), is one of the few reported deep sea sites of precipitation of authigenic carbonates in the Tyrrhenian Sea. Here, the changing composition of the seeping fluids and the dynamic nature of the seepage induced the precipitation of pyrite, siderite and other carbonate phases. The occurrence of this array of authigenic precipitates is thought to be related to fluctuation of the sulfate-methane transition zone (SMTZ).Concretions of authigenic minerals formed in the near sub-bottom sediments of the Paola Ridge were investigated for their geochemical and isotopic composition. These concretions were collected in an area characterized by the presence of two alleged mud volcanoes and three mud diapirs. The mud diapirs are dotted by pockmarks and dissected by normal faults, and are known for having been a site of fluid seepage for at least the past 40 kyrs. Present-day venting activity occurs alongside the two alleged mud volcanoes and is dominated by CO 2 -rich discharging fluids. This discover led us to question the hypothesis of the mud volcanoes and investigate the origin of the fluids in each different domed structure of the study area.In this study, we used stable isotopes (carbon and oxygen) of carbonates coupled with rare earth element (REE) composition of different carbonate and non-carbonate phases for tracing fluid composition and early diagenesis of authigenic precipitates. The analyses on authigenic precipitates were coupled with chemical investigation of venting gas and sea-water.Authigenic calcite/aragonite concretions, from surficial sediments on diapiric structures, have depleted values. The siderite REE pattern shows consistent LREE (light REE) fractionation, MREE (medium REE) enrichment and positive Gd and La anomalies. As shown by the REE distribution, the 13 C-depleted composition and their association with chemosymbiotic fauna, calcite/aragonite precipitated at time of moderate to high methane flux close to the seafloor, under the influence of bottom seawater. Authigenic siderite, on the other hand, formed in the subseafloor, during periods of lower gas discharges under prolonged anoxic conditions within sediments in equilibrium with 13 C-rich dissolved inorganic carbon (DIC) and 18 O-rich water, likely related to methanogenesis and intermittent venting of deep-sourced CO 2 .

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Influence of biotic vs abiotic processes on the genesis of non‐marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance

Bissé

Ekoko

Gerber

et al. 2021

The Depositional Record

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Continental spring carbonates are perfect examples of the interaction of biotic and abiotic processes, and they preserve evidence of the velocity of the flow and the chemical composition of the spring water. This study focuses on non-marine carbonates from fossil and active springs from the Bongongo and Ngol areas along the Cameroon Volcanic Line in South-West Cameroon. Here, hydrothermal fluids reach the surface giving rise to small thermal springs, with temperatures between 31 and 49°C, and streams creating waterfalls, terracettes and barrage carbonate deposits. Petrographic analyses of these carbonates revealed that they are made up of stacked laminae of fibrous coarse crystals of low-Mg calcite and laminae of alternate microsparite and micrite. The fibrous coarsely crystalline calcite, often with feather-like fabric, grows from thin layers of micrite and peloids. Filaments of putative microbial origin are preserved within this peloidal micrite. The laminated microsparite and micrite microfacies is characterised by an intricate mesh of hollow filaments of microbial origin. The long feather-like crystals of calcite formed in fast-flowing water where the enhanced CO 2 degassing has favoured the precipitation of CaCO 3 . The laminated micrite and microsparite, on the other hand, are probably formed in ponds where degassing and CO 2 removal was lower and the calcite precipitation was fostered by microbial activity. The fast-forming carbonates show higher Ce contents and very low total rare earth elements, revealing a preferential uptake of Ce with respect to other rare earth elements. This process would explain the positive or null Ce anomaly in continental spring carbonates elsewhere. The geochemical composition of these carbonates can be used as proxy for the characterisation of fluid/rock interactions between the groundwater and the substratum and for the characterisation of the sources of calcium and other elements that constitute tufa and travertines. The samples from Ngol are characterised by light rare earth element enrichment while those from Bongongo are overall enriched in heavy rare earth elements. Carbonates from both localities have a strong positive Eu anomaly (>4), suggesting a contribution | 103 BISSE Et al.

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Biodetrital carbonates on the Adriatic continental shelf imprinted by oxidation of seeping hydrocarbons

Cited by 19 publications

References 78 publications

Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos Island (Greece): Concretions not archaeological remains

Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos Island (Greece): Concretions not archaeological remains

Authigenic minerals from the Paola Ridge (southern Tyrrhenian Sea): Evidences of episodic methane seepage

Influence of biotic vs abiotic processes on the genesis of non‐marine carbonates along the Cameroon Volcanic Line (Cameroon) and palaeofluid provenance

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