Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary
The crustal structure of two ~150 km long segments across two main tectonic plate boundaries in the North Atlantic, the Gloria Fault and the Terceira Rift are presented. The Gloria Fault stands as a seismogenic fracture zone that generates high magnitude earthquakes, such as the M8.4 event in 1941....
Main Author: | |
---|---|
Other Authors: | , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
2020
|
Subjects: | |
Online Access: | http://hdl.handle.net/10451/44159 |
id |
ftunivlisboa:oai:repositorio.ul.pt:10451/44159 |
---|---|
record_format |
openpolar |
spelling |
ftunivlisboa:oai:repositorio.ul.pt:10451/44159 2023-05-15T17:36:53+02:00 Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary Batista, Luis Terrinha, Pedro Hübscher, Christian 2020-07-27T10:46:04Z http://hdl.handle.net/10451/44159 eng eng info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBD%2F81351%2F2011/PT http://hdl.handle.net/10451/44159 101473702 openAccess Atlantic Ocean Plate Boundary Gloria Fault Terceira Rift Crustal structure and Mantle serpentinization Domínio/Área Científica::Ciências Naturais::Ciências da Terra e do Ambiente doctoralThesis 2020 ftunivlisboa 2022-07-06T00:04:26Z The crustal structure of two ~150 km long segments across two main tectonic plate boundaries in the North Atlantic, the Gloria Fault and the Terceira Rift are presented. The Gloria Fault stands as a seismogenic fracture zone that generates high magnitude earthquakes, such as the M8.4 event in 1941. Vp and Vs waves were recorded during an active seismic refraction experiment using 18 Ocean Bottom Stations. The velocity model allows discrimination of five layers (L1 to L5), L1 for sediments, L2 for upper crust, L3 for lower crust, L4 for a layer of unknown origin and L5 for mantle. Poisson coefficient from Vp/Vs ratio allowed estimation of layers’ densities. We speculate on L4 origin and nature from velocities and densities. Two possible models, L4 corresponds to a mixture of gabbro and peridotite or to hydrated mantle (serpentinized mantle). The Terceira Rift seismic refraction line comprehends data from the S. Miguel Island. Velocities of S waves were not recorded. The model is based in Vp only. A five layer model is proposed, L1 for volcano-sedimentary layer, L2 for upper crust, L3 for lower crust and L5 for the mantle. L4 between L3 and L5 has a lensoid shape and its velocities suggest either a cumulate gabbro underplated layer or hydrated mantle. A south dipping extensional shear zone aligned with the Monaco Graben was identified from the brittle upper crust and across the lower crust, L4 and mantle. This shear zone coincides with a cluster of seismicity located to the south of S. Miguel Island. To the north of S. Miguel seismicity is barely inexistent and a 20 km long recent landslide with a toe thrust is clearly imaged, suggesting northward tilting of the island caused by the extensional shear zone, the south flank of the Terceira Rift. German Research Foundation, DFG, grant Hu698/19-1 Doctoral or Postdoctoral Thesis North Atlantic Universidade de Lisboa: repositório.UL Tilting ENVELOPE(-54.065,-54.065,49.700,49.700) |
institution |
Open Polar |
collection |
Universidade de Lisboa: repositório.UL |
op_collection_id |
ftunivlisboa |
language |
English |
topic |
Atlantic Ocean Plate Boundary Gloria Fault Terceira Rift Crustal structure and Mantle serpentinization Domínio/Área Científica::Ciências Naturais::Ciências da Terra e do Ambiente |
spellingShingle |
Atlantic Ocean Plate Boundary Gloria Fault Terceira Rift Crustal structure and Mantle serpentinization Domínio/Área Científica::Ciências Naturais::Ciências da Terra e do Ambiente Batista, Luis Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
topic_facet |
Atlantic Ocean Plate Boundary Gloria Fault Terceira Rift Crustal structure and Mantle serpentinization Domínio/Área Científica::Ciências Naturais::Ciências da Terra e do Ambiente |
description |
The crustal structure of two ~150 km long segments across two main tectonic plate boundaries in the North Atlantic, the Gloria Fault and the Terceira Rift are presented. The Gloria Fault stands as a seismogenic fracture zone that generates high magnitude earthquakes, such as the M8.4 event in 1941. Vp and Vs waves were recorded during an active seismic refraction experiment using 18 Ocean Bottom Stations. The velocity model allows discrimination of five layers (L1 to L5), L1 for sediments, L2 for upper crust, L3 for lower crust, L4 for a layer of unknown origin and L5 for mantle. Poisson coefficient from Vp/Vs ratio allowed estimation of layers’ densities. We speculate on L4 origin and nature from velocities and densities. Two possible models, L4 corresponds to a mixture of gabbro and peridotite or to hydrated mantle (serpentinized mantle). The Terceira Rift seismic refraction line comprehends data from the S. Miguel Island. Velocities of S waves were not recorded. The model is based in Vp only. A five layer model is proposed, L1 for volcano-sedimentary layer, L2 for upper crust, L3 for lower crust and L5 for the mantle. L4 between L3 and L5 has a lensoid shape and its velocities suggest either a cumulate gabbro underplated layer or hydrated mantle. A south dipping extensional shear zone aligned with the Monaco Graben was identified from the brittle upper crust and across the lower crust, L4 and mantle. This shear zone coincides with a cluster of seismicity located to the south of S. Miguel Island. To the north of S. Miguel seismicity is barely inexistent and a 20 km long recent landslide with a toe thrust is clearly imaged, suggesting northward tilting of the island caused by the extensional shear zone, the south flank of the Terceira Rift. German Research Foundation, DFG, grant Hu698/19-1 |
author2 |
Terrinha, Pedro Hübscher, Christian |
format |
Doctoral or Postdoctoral Thesis |
author |
Batista, Luis |
author_facet |
Batista, Luis |
author_sort |
Batista, Luis |
title |
Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
title_short |
Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
title_full |
Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
title_fullStr |
Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
title_full_unstemmed |
Structure and tectonics of the crust and Moho discontinuity of the Gloria Fault and Terceira Rift (S. Miguel) along the Nubia-Eurasia plate boundary |
title_sort |
structure and tectonics of the crust and moho discontinuity of the gloria fault and terceira rift (s. miguel) along the nubia-eurasia plate boundary |
publishDate |
2020 |
url |
http://hdl.handle.net/10451/44159 |
long_lat |
ENVELOPE(-54.065,-54.065,49.700,49.700) |
geographic |
Tilting |
geographic_facet |
Tilting |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBD%2F81351%2F2011/PT http://hdl.handle.net/10451/44159 101473702 |
op_rights |
openAccess |
_version_ |
1766136512262438912 |