ANALYSIS AND MODELLING OF LAVA FLOW-FIELDS AND VOLCANO-TECTONICS PROCESSES WITH A FOCUS ON THE AL HARUJ VOLCANIC PROVINCE, CENTRAL LIBYA. / Elshaafi, Abdelsalam.

2017. 412 p.

Research output: ThesisDoctoral Thesis

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@phdthesis{9b724db719324f3685822a1fa09318de,
title = "ANALYSIS AND MODELLING OF LAVA FLOW-FIELDS AND VOLCANO-TECTONICS PROCESSES WITH A FOCUS ON THE AL HARUJ VOLCANIC PROVINCE, CENTRAL LIBYA",
abstract = "The thesis focuses mainly on various aspects of the volcano-tectonics processes in the Al Haruj Volcanic Province (AHVP), central Libya, as well as the emplacement and inflation of the Al-Halaq al Kabir lava flow field of the associated volcanic province. Six main volcanic clusters are identified in Libya. Each is thought to have been supplied with magmas from a deep-seated reservoir, most likely at the crust-mantle boundary. The magmatic overpressure in the AHVP is similar to that of typical regional feeder dykes in many other areas. Numerical modelling and field observations suggest that some feeder-dykes may have used steeply dipping normal fault zones as part of their paths to the surface. Hence the various orientations of crater rows or volcanic fissures are likely to be partly controlled by the directions of pre-existing faults. Together the monogenetic volcanoes in the AHVP form two distinct density groups which are interpreted as separate volcanic systems. Each system is thought to be fed by a deep-seated and very extensive magma reservoir. From the eruptive volumes and the density distributions of the volcanoes, we estimate the volumes of the reservoirs. Numerical models are used to investigate local variation in the stress field resulting from general doming of the area during the late Miocene, as well as local loading by magma reservoirs, including the effects of various mechanical properties of the crustal layers, so as to explain the variation in space and time of the volcanic activity in this part of Libya. The inflation features are used to understand better the emplacement mechanism. The preferred pathways beneath upper lava crust are most favourable for thermally efficient lava delivery from the vent system to the distal portion of the lava flow field in the Al Haruj region. Numerical models suggest stress interaction between the six volcanic systems, encouraging shared dykes. The present work also investigates the mechanics of central volcanoes and caldera collapses in the Tibesti Volcanic Province (TVP), NW Chad.",
keywords = "Lava shields , Volcanic fissures, Eruption mechanisms, Magma reservoirs, Inflation features , Monogenetic volcanoes, Volcano-tectonic forcing, Volcano interaction, Crustal stresses, Lava flow field",
author = "Abdelsalam Elshaafi",
year = "2017",
month = oct,
day = "30",
language = "English",
school = "Royal Holloway, University of London",

}

RIS

TY - THES

T1 - ANALYSIS AND MODELLING OF LAVA FLOW-FIELDS AND VOLCANO-TECTONICS PROCESSES WITH A FOCUS ON THE AL HARUJ VOLCANIC PROVINCE, CENTRAL LIBYA

AU - Elshaafi, Abdelsalam

PY - 2017/10/30

Y1 - 2017/10/30

N2 - The thesis focuses mainly on various aspects of the volcano-tectonics processes in the Al Haruj Volcanic Province (AHVP), central Libya, as well as the emplacement and inflation of the Al-Halaq al Kabir lava flow field of the associated volcanic province. Six main volcanic clusters are identified in Libya. Each is thought to have been supplied with magmas from a deep-seated reservoir, most likely at the crust-mantle boundary. The magmatic overpressure in the AHVP is similar to that of typical regional feeder dykes in many other areas. Numerical modelling and field observations suggest that some feeder-dykes may have used steeply dipping normal fault zones as part of their paths to the surface. Hence the various orientations of crater rows or volcanic fissures are likely to be partly controlled by the directions of pre-existing faults. Together the monogenetic volcanoes in the AHVP form two distinct density groups which are interpreted as separate volcanic systems. Each system is thought to be fed by a deep-seated and very extensive magma reservoir. From the eruptive volumes and the density distributions of the volcanoes, we estimate the volumes of the reservoirs. Numerical models are used to investigate local variation in the stress field resulting from general doming of the area during the late Miocene, as well as local loading by magma reservoirs, including the effects of various mechanical properties of the crustal layers, so as to explain the variation in space and time of the volcanic activity in this part of Libya. The inflation features are used to understand better the emplacement mechanism. The preferred pathways beneath upper lava crust are most favourable for thermally efficient lava delivery from the vent system to the distal portion of the lava flow field in the Al Haruj region. Numerical models suggest stress interaction between the six volcanic systems, encouraging shared dykes. The present work also investigates the mechanics of central volcanoes and caldera collapses in the Tibesti Volcanic Province (TVP), NW Chad.

AB - The thesis focuses mainly on various aspects of the volcano-tectonics processes in the Al Haruj Volcanic Province (AHVP), central Libya, as well as the emplacement and inflation of the Al-Halaq al Kabir lava flow field of the associated volcanic province. Six main volcanic clusters are identified in Libya. Each is thought to have been supplied with magmas from a deep-seated reservoir, most likely at the crust-mantle boundary. The magmatic overpressure in the AHVP is similar to that of typical regional feeder dykes in many other areas. Numerical modelling and field observations suggest that some feeder-dykes may have used steeply dipping normal fault zones as part of their paths to the surface. Hence the various orientations of crater rows or volcanic fissures are likely to be partly controlled by the directions of pre-existing faults. Together the monogenetic volcanoes in the AHVP form two distinct density groups which are interpreted as separate volcanic systems. Each system is thought to be fed by a deep-seated and very extensive magma reservoir. From the eruptive volumes and the density distributions of the volcanoes, we estimate the volumes of the reservoirs. Numerical models are used to investigate local variation in the stress field resulting from general doming of the area during the late Miocene, as well as local loading by magma reservoirs, including the effects of various mechanical properties of the crustal layers, so as to explain the variation in space and time of the volcanic activity in this part of Libya. The inflation features are used to understand better the emplacement mechanism. The preferred pathways beneath upper lava crust are most favourable for thermally efficient lava delivery from the vent system to the distal portion of the lava flow field in the Al Haruj region. Numerical models suggest stress interaction between the six volcanic systems, encouraging shared dykes. The present work also investigates the mechanics of central volcanoes and caldera collapses in the Tibesti Volcanic Province (TVP), NW Chad.

KW - Lava shields

KW - Volcanic fissures

KW - Eruption mechanisms

KW - Magma reservoirs

KW - Inflation features

KW - Monogenetic volcanoes

KW - Volcano-tectonic forcing

KW - Volcano interaction

KW - Crustal stresses

KW - Lava flow field

M3 - Doctoral Thesis

ER -