Mud volcanoes from the Alboran Sea: materials and vulcano-sedimentary and diagenetic processes involved
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López Rodríguez, CarmenEditorial
Universidad de Granada
Departamento
Universidad de Granada. Programa Oficial de Doctorado en: Ciencias de la Tierra; Consejo Superior de Investigaciones Científicas (CSIC). Instituto Andaluz de Ciencias de la TierraMateria
Volcanes Sedimentos (Geología) Análisis Alborán Biogeoquímica
Materia UDC
551.21 551.3.051 2507 2506
Date
2016Fecha lectura
2016-01-08Referencia bibliográfica
López Rodríguez, C.F. Mud volcanoes from the Alboran Sea: materials and vulcano-sedimentary and diagenetic processes involved. Granada: Universidad de Granada, 2016. [http://hdl.handle.net/10481/41550]
Sponsorship
Tesis Univ. Granada. Programa Oficial de Doctorado en: Ciencias de la Tierra; Para el desarrollo de esta Tesis Doctoral se ha contado con una beca-contrato (2+2) del Programa JAE-Predoc del Consejo Superior de Investigaciones Científicas (CSIC). Este trabajo ha sido financiado dentro de los proyectos del Plan Nacional CGL2008-03474-E/BTE, CTM2009-07715 y CGL2011-14141-E financiados por el Ministerio de Ciencia e Innovación (MICINN) del Gobierno de España. También se agradece la financiación de los Fondos Europeos de Desarrollo Regional (FEDER) de la Comunidad Económica Europea, a la acción especial CGL2011-14141-E financiada por el Ministerio de Ciencia e Innovación (MICINN) del Gobierno de España, los proyectos RNM-3713 y Grupo de Investigación RNM215 de la Junta de Andalucía y a los programas Topomed CGL2008-03474 y Consolider Ingenio 2010- CSD2006-00041 del Ministerio de Ciencia e Innovación del Gobierno de España.Abstract
In the westernmost Mediterranean, a broad field of mud volcanoes (MVs) and pockmarks occurs in
the West Alboran Basin (WAB). These typical sea-floor structures can be found in the inner part of
the Gibraltar Arc and occur above a major sedimentary depocenter encompassing early Miocene to
Holocene sedimentary sequences, up to 7 km thick. In this region the development of mud volcanism
is related to the presence of a large shale-diapiric province in the WAB. The shale-diapiric province
underlying the MV fields is derived from deep overpressured units (undercompacted Miocene shales
and olistostromes), which in turn overlie a metamorphic basement. MV occurrences are related to tectonic
features (faults): they rise under Holocene tectonics, and grow atop diverse diapiric structures.
Various studies have focused on the tectonic context and morphology of these mud volcanic edifices.
Still, however, little is known about the nature and components of the extruded materials (solid and
fluids phases).
This PhD thesis involves mineralogical, geochemical and biogeochemical investigations of mud-volcanic
products and related sediments from some MVs and pockmarks of the Alboran Sea, named
Perejil, Kalinin, Schneider´s Heart, Carmen, Maya Dhaka, Marrakesh, Granada and Mulhacen, and also
Crow´s foot pockmark. The research is performed on gravity cores that comprised extruded materials’
from the MVs (mud breccias) and associated hemipelagic sediment samples. A entailed multi-proxy
approach including organic (lipid biomarkers) and inorganic (mineralogy, sedimentology and pore
water geochemistry) determinations have been performed both on fluids and solid phases. This study
provides important insights about the composition and provenance of the volcanic extruded material
(mud breccia) and hemipelagic sediments involved also including biogeochemical results closely related
with the discharge of hydrocarbon-rich fluids to the seafloor through MVs. It also pursues a better
understanding of the origin of the extruded muds as well as of the mud volcanism in the WAB. Hemipelagic facies draping mud volcanic structures exemplify mud volcanic activity. The existence of
several interbedded intervals of hemipelagic sediments between mud breccias indicates the recurrence
of volcanic pulses (episodes of mud extrusions), which result in discrete and successive emission
of volcanic fluxes in the form of mud breccia intervals. Presence or absence of hemipelagic facies
drapping mud edifices inform about the age of the mud volcanic events. Active edifices present a lack
of hemipelagic drapes covering the last (uppermost) mud breccia interval. Only craters of Carmen and
Perejil MVs lack hemipelagic drapes which indicate current or very recent mud flow and fluid eruptions
as well as their current activity. This is supported by further evidence of most recent activity at these
two MVs, such as gas bubbling or living chemosynthetic fauna. Thus, the occurrence of hemipelagic
intervals intercalated with mud breccias points to successive episodes of volcanic activity resulting in
mud flows that were draped by normal marine sediments.
Inactive MVs present well developed hemipelagic drapes that lay covering the MV deposits. The absence
of detectable methane discharge and nonexistence of living chemosynthetic fauna at these MVs
support their inactivity. These features are found at Kalinin, Maya, Dhaka, Marrakech, Granada and
Mulhacen which are considered inactive. The relative homogeneity in mineralogy and geochemistry of these sediment drapes, covering or interbedded
with mud breccia intervals, indicates that they are generally not affected by the seepage
venting. Radiocarbon dating of Globigerina Bulloides in hemipelagic intervals reveals the age of the
older eruption occurred 10.8 Ka BP at Carmen whereas the most recent eruption happened 0.7 ka BP
at Marrakech.