Geophysical evidence of mud diapirism on the Mediterranean Ridge accretionary complex

Camerlenghi, Angelo; Cita, Maria Bianca; Vedova, Bruno Della; Fusi, Nicoletta; Mirabile, L.; Pellis, G.

doi:10.1007/bf01203423

Cited by 147 publications

(144 citation statements)

References 42 publications

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“…data). (2) Shipboard organic geochemical results (Emeis, Robertson, Richter, et al, 1996) support earlier results (Camerlenghi et al, 1995), indicating the presence of mature hydrocarbons within the mud volcano sediments, requiring an origin of estimated >2 km depth. (3) The common presence of ankerite in the matrix suggests deep burial diagenesis of several kilometers (Robertson and Kopf,Chap.…”

Section: Depth Of Origin Of the Matrixsupporting

confidence: 76%

“…Evaporites on a topographic high are expected to be dominated by gypsum, without halite, based on comparisons with on-land marginal settings (Crete and Cyprus), but gypsum was not found in the two mud volcanoes drilled. The implication is that the halite was derived from a greater depth, either within an accretionary wedge several kilometers beneath, or at still greater depth from the present-day décollement zone estimated at 5−7 km mbsf (Camerlenghi et al, 1995). A possibly shallow (<2 km) origin of some of the matrix is apparently supported by the clay mineralogical evidence of smectite and kaolinite, which does not indicate very deep burial diagenesis (Robertson and Kopf,Chap.…”

Section: Depth Of Origin Of the Matrixmentioning

confidence: 81%

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Tectonic setting and processes of mud volcanism on the Mediterranean Ridge accretionary complex: evidence from Leg 160

Robertson¹,

Kopf²

1998

Proceedings of the Ocean Drilling Program, 160 Scientific Results

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Mud volcanism was initiated when overpressured muds rose through the Mediterranean Ridge accretionary prism. Early mud volcanism was marked by eruption of coarse clastic sediments forming small cones of debris flow deposits and turbidites, followed by eruption of large volumes of clast-rich matrix-supported debris flows. Eruption was accompanied by progressive subsidence to form moat-like features. Later, clast-poor mud flows spread laterally and built up a flat-topped cone (Napoli mud volcano). Clasts in the mud volcano sediments are mainly angular and up to 0.5 m in size. These clasts are dominated by claystone, sandstone, and limestone of early-middle Miocene age that were previously accreted. Matrix material of the mud breccias probably originated from Messinian evaporite-rich sediments located within the décollement zone beneath the accretionary wedge, at an estimated depth of 5−7 km. Pressure release triggered hydrofracturing of poorly consolidated mud near the seafloor. Eruption was accompanied by release of large volumes of hydrocarbon gas. Conditions were suitable for gas hydrate genesis at shallow depths beneath the seafloor at the Milano mud volcano. The mud volcanism is probably related to backthrusting concentrated along the rear of the accretionary wedge near a backstop of continental crust to the north. Clasts within the mud breccias were mainly derived from the North African passive margin, but subordinate lithoclastic ophiolite-related material was also derived from the north, probably from now largely obliterated higher thrust sheets of Crete. Comparisons show that in contrast to other mud volcanoes both on the seafloor (Barbados) and on land (Trinidad), which are usually relatively transient features, mud volcanism on the Mediterranean Ridge has persisted for >1 m.y. A revised hypothesis of mud volcanism at the Ocean Drilling Program sites is proposed, in relation to progressive tectonic evolution of the Mediterranean Ridge accretionary complex.

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Section: Depth Of Origin Of the Matrixsupporting

confidence: 76%

Section: Depth Of Origin Of the Matrixmentioning

confidence: 81%

Tectonic setting and processes of mud volcanism on the Mediterranean Ridge accretionary complex: evidence from Leg 160

Robertson¹,

Kopf²

1998

Proceedings of the Ocean Drilling Program, 160 Scientific Results

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“…The start of breakdown (smectite-to-illite transformation) elsewhere is at temperatures of about 70°−96°C, which is equivalent to 2−3 km burial at normal geothermal gradients (Hower et al, 1976;Jennings and Thompson, 1986;Whitney, 1990). However, in a low-heat-flow accretionary wedge setting such as the Mediterranean Ridge (Camerlenghi et al, 1995), the depth of initial breakdown could be greater. The persistence of smectite is thus compatible with the estimated 5− 7 km depth of the subduction décollement zone beneath the Mediterranean Ridge (Camerlenghi et al, 1995;Schulz et al, l997).…”

Section: Sources Of Clay Mineralsmentioning

confidence: 99%

“…However, in a low-heat-flow accretionary wedge setting such as the Mediterranean Ridge (Camerlenghi et al, 1995), the depth of initial breakdown could be greater. The persistence of smectite is thus compatible with the estimated 5− 7 km depth of the subduction décollement zone beneath the Mediterranean Ridge (Camerlenghi et al, 1995;Schulz et al, l997).…”

Section: Sources Of Clay Mineralsmentioning

confidence: 99%

“…Mud volcanoes south of Crete were initially not distinguished from a more widespread, seismically diffracting "cobblestone topography" (Kastens, 1981). More recently, however, the mud volcanoes were identified as "mud diapirs" on the basis of seismic reflection and piston coring studies (Cita et al, 1981(Cita et al, , 1989(Cita et al, , 1995(Cita et al, , 1996a(Cita et al, , 1996bCamerlenghi et al, 1992Camerlenghi et al, , 1995. Superficial features were revealed in 1993 by sidescan sonar studies, combined with additional coring, and the Napoli mud volcano was shown to be actively venting (Limonov et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Origin of clasts and matrix within the Milano and Napoli mud volcanoes, Mediterranean Ridge accretionary complex

Robertson¹,

Kopf²

1998

Proceedings of the Ocean Drilling Program, 160 Scientific Results

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Petrographic and mineralogical studies of clasts and matrix in the Milano and Napoli mud volcanoes drilled during Ocean Drilling Program Leg 160 provide important clues about depositional processes, provenance, and the tectonic setting of deepsea sediments that accumulated before genesis of the Mediterranean Ridge mud volcanoes.The clasts recovered from both mud volcanoes are mainly mudstone and claystone, calcareous siltstone, quartzose sandstone and siltstone, shallow-water-derived limestone, and pelagic carbonate. Biostratigraphic evidence indicates mainly early and middle Miocene ages for fossiliferous clasts, with the older microfossils being reworked. Textural evidence (grading) suggests that the clastic lithologies are turbidites. Sources of the sandstones were mainly plutonic igneous and subordinate metamorphic rocks. Sporadic, exceptionally well-rounded, quartz grains may be of eolian origin and were probably derived from the Precambrian basement of North Africa. Shallow-water-derived carbonates were also redeposited as calciturbidites, with variable admixing with siliciclastic and pelagic carbonate, which indicates shared depositional pathways. Pelagic carbonates (packstones) were redeposited basinward as calciturbidites from a deep-sea carbonate slope that formed part of the North African continental margin. During the middle Miocene, the background sedimentation was in situ pelagic carbonate. In addition, relatively rare, texturally immature, lithic sandstones include serpentinite, basalt, and radiolarian chert, of ophiolite-related origin. This material was derived from the orogenic areas to the north, possibly originally from the higher thrust sheets of Crete, before late Miocene and subsequent erosion and extensional downfaulting.The texture and composition of the mud and clay matrix provide clues about the mode of the mud volcanism. The matrix of the mud debris flows includes numerous, small, angular clasts of unfossiliferous claystone and shardlike fragments, which show pseudolamination, microshearing, and crosscutting veinlets, features that are taken as evidence for the involvement of high fluid pressure in clast and matrix formation (hyrofracturing).

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Hydrocarbon seepage and its sources at mud volcanoes of the Kumano forearc basin, Nankai Trough subduction zone

Pape

Geprägs

Hammerschmidt

et al. 2014

Geochem Geophys Geosyst

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Twelve submarine mud volcanoes (MV) in the Kumano forearc basin within the Nankai Trough subduction zone were investigated for hydrocarbon origins and fluid dynamics. Gas hydrates diagnostic for methane concentrations exceeding solubilities were recovered from MVs 2, 4, 5, and 10. Molecular ratios (C 1 /C 2 < 250) and stable carbon isotopic compositions (d 13 C-CH 4 >240& V-PDB) indicate that hydratebound hydrocarbons (HCs) at MVs 2, 4, and 10 are derived from thermal cracking of organic matter. Considering thermal gradients at the nearby IODP Sites C0009 and C0002, the likely formation depth of such HCs ranges between 2300 and 4300 m below seafloor (mbsf). With respect to basin sediment thickness and the minimum distance to the top of the plate boundary thrust we propose that the majority of HCs fueling the MVs is derived from sediments of the Cretaceous to Tertiary Shimanto belt below Pliocene/Pleistocene to recent basin sediments. Considering their sizes and appearances hydrates are suggested to be relicts of higher MV activity in the past, although the sporadic presence of vesicomyid clams at MV 2 showed that fluid migration is sufficient to nourish chemosynthesis-based organisms in places. Distributions of dissolved methane at MVs 3, 4, 5, and 8 pointed at fluid supply through one or few MV conduits and effective methane oxidation in the immediate subsurface. The aged nature of the hydrates suggests that the major portion of methane immediately below the top of the methane-containing sediment interval is fueled by current hydrate dissolution rather than active migration from greater depth.

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Geophysical evidence of mud diapirism on the Mediterranean Ridge accretionary complex

Cited by 147 publications

References 42 publications

Tectonic setting and processes of mud volcanism on the Mediterranean Ridge accretionary complex: evidence from Leg 160

Tectonic setting and processes of mud volcanism on the Mediterranean Ridge accretionary complex: evidence from Leg 160

Origin of clasts and matrix within the Milano and Napoli mud volcanoes, Mediterranean Ridge accretionary complex

Hydrocarbon seepage and its sources at mud volcanoes of the Kumano forearc basin, Nankai Trough subduction zone

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