Skip to Main content Skip to Navigation
Theses

Mud volcanism and fluid emissions in Eastern Mediterranean neotectonic zones

Abstract : Mud volcanoes which result from the extrusion of fluid-rich mud flows has long been known onshore or at sea, mainly within active belts but also on highly sedimented passive margins. However, the interest of the scientific community in submarine mud volcanoes and associated phenomena has increased recently as their potential importance has been recognized in several areas. These areas include ocean margin shaping, greenhouse gases release and induced climate change, energy for chemosynthetically based life, petroleum prospecting, and gas hydrates accumulation as a potential energy resource. Therefore, a multidisciplinary approach is required to understand mud volcanism and the inter-relationships among gases, bacteria, benthic communities, sediment stability, debris flow, tectonics and the geophysical and geochemical signature of the mud volcanic products.
This thesis is part of the MEDINAUT and MEDMUD programmes, both international and national multidisciplinary research focussed on the Eastern Mediterranean Sea as a natural laboratory for mud volcanism and fluid emissions. The principal goal of this thesis is to determine the geological controls on mud volcanism in the area and the physical origins of the acoustic signature of the mud volcano deposits. The dataset, collected during several marine expeditions (ANAXIPROBE, PRISMED II, MEDINAUT, MEDINETH), is presented in Chapter 2 and comprises multibeam bathymetry and imagery, seismic profiles, gravity data, sidescan sonar records, submersible video records, and sedimentary cores. The thesis is divided in two parts: the first part (Chapters 3 and 4) examines the geology and sedimentology of mud volcanoes in the Eastern Mediterranean Sea, whereas the second part (Chapters 5 and 6), more specifically focussed on the Anaximander Mountains area, south of Turkey, deals with the current stress field and active deformation at the junction between the Hellenic and Cyprus Arcs, and its relation with mud volcanism evolution.
Sedimentology and geology of Eastern Mediterranean mud volcano deposits - In Chapter 3, the in situ observations of the seafloor at mud volcanoes (as analysed from video recordings from the submersible “Nautile” and from deep tow video) have revealed common characteristics at cold seeps, such as carbonate crust constructions and specific chemosynthetic-based fauna. The mapping of the seafloor characteristics and the degree of colonization by benthic fauna can be correlated with the observed backscatter variations. Mud volcanism activity presents a high variability related to the intensity of the fluid fluxes and, probably, the age of the mud flows and seeps. So, the geophysical signature can be related to spatial and temporal variations of mud volcanism. Mud volcanic activity also depends on which type of phenomenon is considered (e.g. fluid emissions, mud eruptions, biological activity) and at which scale.
Chapter 4 discusses the depositional environment, age, and depth of the lithological unit from which the mud breccia is extruded. The clay mineralogy of all the studied samples from the mud matrix reveals a similar assemblage that is dominated by the presence of smectite (up to 90% of the total clay minerals amount) and is comparable to smectite-rich terrigeneous units of Messinian age. The absence of diagenetic transformations indicates a shallow depth for the remobilization of the mud reservoir. This is of direct relevance (as a constraint) to geochemical research into the depth of origin of seep fluids.

Tectonic control of mud volcanism: example of the Anaximander Mountains area at the junction between the Hellenic and the Cyprus Arcs - The Anaximander Mountains, a complex of three distinct seamounts rising more than 1000 m above the surrounding sea-floor, are formed by crustal blocks rifted from southern Turkey. They form with the surrounding areas (Florence Rise structure, Isparta Angle in SW Turkey) a tectonic accommodation zone between the active deformation in the Aegean-SW Turkey region and the tectonically quieter Cyprus region. The structural pattern of the area is examined in Chapter 5 and indicates that progressive adjustment to incipient collision developed into a broad zone of NW-SE transpressive wrenching. The mud volcanoes are observed along the dominant structures of the western Cyprus Arc (eastern Anaximander Mountains and Florence Rise) where major longitudinal N150°-trending normal/oblique faults as well as crosscutting N070°-oriented sinistral strike slip faults occur.
Chapter 6 focuses on a detailed analysis of the relationship between mud volcanoes and tectonic features from O.R.E.Tech deep-tow sidescan sonar and subbottom profiler data obtained during the 1999 MEDINETH expedition. The fault mapping indicates that several eastern Mediterranean mud volcanoes in the Anaximander Mountains and along the Florence Rise are structurally controlled. The faults are inferred to provide pathways for over-pressured mud and fluids, and mud volcanoes appear related to both major and secondary faulting within the regional stress field. This analysis reveals the fundamental role of transcurrent and extensional tectonics, suggesting that the extensive constraint generated by strike-slip and normal faults facilitates mud extrusion.
Chapter 7 reviews the principal results from Chapter 3 to 6 and integrates them with geochemical and microbiological analyses also carried out within the MEDMUD programme to give insight into the emplacement and evolution of mud volcanoes as well as the origin of both the fluids and the solid phase of the expelled material.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00007644
Contributor : Tiphaine Zitter <>
Submitted on : Monday, December 6, 2004 - 11:27:14 AM
Last modification on : Saturday, November 9, 2019 - 1:33:48 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:40:29 PM

Identifiers

  • HAL Id : tel-00007644, version 1

Collections

Citation

Tiphaine A. C. Zitter. Mud volcanism and fluid emissions in Eastern Mediterranean neotectonic zones. Applied geology. Vrije Universiteit, 2004. English. ⟨tel-00007644⟩

Share

Metrics

Record views

539

Files downloads

2115