23 documents found, page 1 of 3
From the lebombo monocline to the Mozambique deep basin, using combined wide-an...
Moulin, Maryline; Leprêtre, Angelique; Verrier, Fanny; Schnürle, Philippe; Evain, Mikael; Clarens, Philippe; Thompson, Joseph; Dias, NunoThe North Natal valley (NNV), South Mozambique margin, is a key area for the understanding of the SW Indian Ocean history since the Gondwana break-up as its crustal nature and geometry strongly impacted the recon-struction of the paleogeography before the rifting. It is also of considerable importance for the understanding of the evolution of a margin system as the NNV is situated at the transition between dive...
Crustal structure across the São Miguel Island (Azores, North Atlantic) and tec...
Batista, L.; Hübscher, C.; Terrinha, P.; Matias, L.; Afilhado, Alexandra; Loureiro, A.; Weiß, B.The crustal and uppermost lithospheric mantle of the São Miguel Island in the Azores Plateau was investigated using one 160 km long refraction and wide angle refection seismic profle across the island and the Terceira Rift along with multichan nel seismic refection profles on the top of it. P-wave velocity model shows that São Miguel Island is made up of 5 crustal layers. The sedimentary sequence varies between...
Deep structure of the Pará-Maranhão/Barreirinhas passive margin in the equatori...
Aslanian, Daniel; Gallais, Flora; Afilhado, Alexandra; Schnurle, Philippe; Moulin, Maryline; Evain, Mikael; Dias, Nuno; Soares, José; Fuck, ReinhartThe Pará-Maranhão/Barreirinhas margin, North Brazil, is a pull-apart passive margin, with two strike-slip borders, formed during the opening of the Equatorial Atlantic Ocean during Cretaceous time. Its geometry and evolution are speculative due to the lack of information on the crustal structure and the crustal nature. We present here the E-W profiles of the MAGIC (Margins of brAzil, Ghana and Ivory Coast) deep...
Imaging early oceanic crust spreading in the Equatorial Atlantic Ocean: insight...
Moulin, Maryline; Schnurle, Philippe; Afilhado, Alexandra; Gallais, Flora; Dias, Nuno; Evain, Mikael; Soares, José; Fuck, ReinhardtDuring the MAGIC (Margins of brAzil, Ghana, and Ivory Coast) experiment, five combined wide-angle, and reflection seismic profiles were acquired in the Pará-Maranhão/Barreirinhas/Ceará basins northern Brazil. This is a pull-apart passive margin, with two strike-slip borders. The equipment deployed includes 143 sea-bottom seismometers (OBS), a 4.5-km seismic streamer, and a 7587-in3 airgun array. In this paper, ...
The limpopo magma-rich transform margin, south Mozambique: 1. Insights from dee...
Watremez, L.; LEROY, Sylvie; D'Acremont, Elia; Roche, Vincent; Evain, Mikael; Lepretre, A.; Verrier, F.; Aslanian, Daniel; Dias, NunoA variety of structures results from the interplay of evolving far-field forces, plate kinematics, and magmatic activity during continental break-up. The east Limpopo transform margin, offshore northern Mozambique, formed as Africa and Antarctica separated during the mid-Jurassic period break-up of the Gondwana supercontinent. The nature of the crust onshore has been discussed for decades in an effort to resolv...
Deep structure of the North Natal Valley (Mozambique) using combined wide-angle...
Lepretre, A.; Schnurle, P.; Evain, Mikael; Verrier, F.; Moorcroft, D.; Clarens, P. de; Corela, C.; Afilhado, Alexandra; Loureiro, Afonso; LEROY, SylvieThe North Natal Valley (NNV) and the Mozambique Coastal Plain (MCP) are key areas for the understanding of the SW Indian Ocean history since the Gondwana break-up. Nevertheless, the deep structures and the nature of the NNV and MCP remain discussed in the absence of deep geophysical data. In 2016, the NNV, MCP and Limpopo margin (LM) have been investigated along seven wide-angle and MCS profiles. The combined w...
Gondwana breakup: messages from the North Natal Valley
Moulin, Maryline; Aslanian, Daniel; Evain, Mikael; Lepretre, Angelique; Schnurle, Philippe; Verrier, Fanny; Thompson, Joseph; De Clarens, PhilippeThe Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide-angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30-km-thick crust that we argue to be of continental nature. This falsifies all the most recent pal...
Rifting of the Southwest and West Iberia Continental Margins
Terrinha, Pedro; Kullberg, José Carlos; Neres, Marta; Alves, Tiago; Ramos, Adrià; Ribeiro, Carlos; Mata, João; Pinheiro, Luís; Afilhado, AlexandraThe West and SouthWest Margins of Iberia started their formation as intra-continental rifts during initial break up of Pangea in Triassic times. The tectono-stratigraphic record of the Algarve, Alentejo and Lusitanian basins and their offshore prolongation documents the syn-rift, post-rift and passive margin phases of the rifting process as well as three magmatic cycles of tholeiite to alkaline affinities. Alth...
Imaging exhumed lower continental crust in the distal Jequitinhonha basin, Brazil
Loureiro, Afonso; Schnürle, P.; Klingelhoefer, Frauke; Afilhado, Alexandra; Pinheiro, J.; Evain, Mikael; Gallais, F.; Dias, Nuno; Rabineau, MarinaTwelve combined wide-angle refraction and coincident multi-channel seismic profiles were acquired in the Jequitinhonha-Camamu-Almada, Jacuípe, and Sergipe-Alagoas basins, NE Brazil, during the SALSA experiment in 2014. Profiles SL11 and SL12 image the Jequitinhonha basin, perpendicularly to the coast, with 15 and 11 four-channel ocean-bottom seismometers, respectively. Profile SL10 runs parallel to the coast, c...
Accurate ocean bottom seismometer positioning method inspired by multilateratio...
Benazzouz, Omar; Pinheiro, Luis; Matias, Luis; Afilhado, Alexandra; Herold, Daniel; Haines, Seth S.The positioning of ocean bottom seismometers (OBS) is a key step in the processing flow of OBS data, especially in the case of self popup types of OBS instruments. The use of first arrivals from airgun shots, rather than relying on the acoustic transponders mounted in the OBS, is becoming a trend and generally leads to more accurate positioning due to the statistics from a large number of shots. In this paper, ...