21 documents found, page 1 of 3

Noble Gas Constraints on the Origin of the Azores Hotspot

Noble gas geochemistry is a valuable tool for assessing the nature of contributors to magma mantle sources. In this chapter, we analyse previously published data regarding helium and neon in the Azores to discuss the origin of the Azores archipelago. After the pioneering works of Kurz et al. (1982a, 1990) examining helium isotopic variations along the Mid-Atlantic Ridge (MAR) between 28°N and 53°N and on São Mi...

The 1998-2001 submarine lava balloon eruption at the Serreta Ridge (Azores arch...

The most recent submarine eruption observed offshore the Azores archipelago occurred between 1998-2001 along the submarine Serreta ridge (SSR), ~4-5 nautical miles WNW of Terceira Island. This submarine eruption delivered abundant basaltic lava balloons floating at the sea surface and significantly changed the bathymetry around the eruption area. Our work combines bathymetry, volcanic facies cartography, petrog...

The 1998-2001 submarine lava balloon eruption at the Serreta ridge (Azores arch...

The most recent submarine eruption observed offshore the Azores archipelago occurred between 1998 and 2001 along the submarine Serreta ridge (SSR), similar to 4-5 nautical miles WNW of Terceira Island. This submarine eruption delivered abundant basaltic lava balloons floating at the sea surface and significantly changed the bathymetry around the eruption area. Our work combines bathymetry, volcanic facies carto...

Helium isotope systematics in the vicinity of the Azores triple junction: Const...

We present new He isotopic data from subaerial and submarine samples collected along the Terceira Rift (Azores Plateau) in order to constrain the sources involved in the Azoresmagmatismin the unique geodynamic contextof the Azores triple junction. Lower thanMORB 4He/3He isotopic ratioswere determined on olivines fromthe Terceira Island and the adjacent Serreta submarine ridge (down to≈69,000;≈10.5 R/Ra),which i...

Paisagens de afetos na gravura de Irene Ribeiro

He and Ne isotopic ratios from the Terceira Rift (Azores): Constraints on the b...

We present He and Ne isotopic data from subaerial and submarine samples collected along the Terceira Rift. Graciosa Island as well as the western end of S. Miguel Island and D. João de Castro Bank display 4He/3He ratios similar to those observed along the MAR segments located to the north of the Azores Triple Junction area. Conversely, samples from the south Hirondelle Basin display a 4He/3He ratio similar to t...

Hydrogeochemical survey of CO2 geological leakage using noble gases: Applicatio...

Significant natural CO2 emissions have been measured across the caldera of Furnas (São Miguel Island, Azores) allowing us to consider the area as a CO2 leakage analogue. During two field trips, we have collected twenty springs in purpose to measure CO2 contents (Dissolved Inorganic Carbon and "13C) and noble gas isotopic compositions (He and Ne) and for seventeen water samples, major ions chemistry. The correct...

Helium and neon isotopes in São Miguel island basalts, Azores Archipelago: New ...

Lavas from the São Miguel Island, Azores Archipelago, have peculiar isotopic compositions, including radiogenic lead and strontium and un-radiogenic neodymium. The peculiar isotopic trend of São Miguel is evident in the lead-lead diagram where both 207Pb/204Pb and 208Pb/204Pb ratios are high for a given 206Pb/204Pb ratio compared to other oceanic island basalts. This signature is unique among OIBs and is partic...

Cosmogenic helium and neon extracted by crushing: A technique for discriminatin...

The helium and neon isotopic compositions of olivines coming from a 11Ma old xenolith sampled at Mt. Hampton (West Antarctica) were analyzed by crushing and heating. The 4He/3He isotopic ratio obtained by crushing varies between 1340 and 6300 (R/Ra between 115 and 539) with 4He content around 3-5 10-10 ccSTP/g confirming that cosmogenic helium can be extracted by crushing [Scarsi, 2000; Yocochi et al., 2004]. T...

He and Ne isotopic ratios along the Terceira Rift: implications for the Azores ...

Noble gas data (He and Ne) on olivine phenocrysts obtained from Azores’ lavas sampled along the Terceira Rift will be presented in this work. The Terceira Rift is considered as one of the slowest spreading system in the world (Vogt & Jung, 2004). Lava samples were collected inland at S. Miguel, Terceira, Graciosa, Pico and Faial Islands as well at sea at D. João de Castro Bank and south Hirondelle basin, the la...