Pleistocene alkaline rocks of Martin Vaz volcano, South Atlantic: low-degree partial melts of a CO₂-metasomatized mantle plume

Isotopic constraints on Davis bank, Vitória-Trindade Ridge: A Revised Petrogenetic Model

“…The bulk rock Sr-Nd isotopic compositions of the Davis Bank and those of the Vitória seamount are distinct from that of the depleted mantle and differ from the other seamounts and islands from the VTR (Supplementary Table 1). The 87 Sr/ 86 Sr measured values of volcanic rocks of the Davis Bank range from 0.704014 to 0.704036, which are similar to the Vitória Seamount (0.704054 and 0.704031; Maia et al, 2021) and are at the higher end of the range defined by other VTR samples (0.703611-0.704130; Halliday et al, 1992;Marques et al, 1999;Fodor and Hanan, 2000;Siebel et al, 2000;Bongiolo et al, 2015;Skolotnev and Peive, 2017;Santos et al, 2018a). In addition, they have a more radiogenic composition than the Abrolhos Volcanic Complex (AVC; 0.703607-0.703946; Fodor et al, 1989).…”

“…1): Jaseur 29.8 ± 6.6 Ma (U-Pb zircon dating; Skolotnev et al, 2011); Davis ca. 21 Ma; ( 40 Ar/ 39 Ar dating; Santos, 2016;Skolotnev and Peive, 2017, see references for details and this work); and the Trindade-Martin Vaz archipelago ranging from 3.4 to 0.3 Ma ( 40 Ar/ 39 Ar dating; Santos, 2016;Santos et al, 2018a;Monteiro et al, 2021).…”

“…The VTR corresponds to a remarkable alignment of alkaline volcanic buildings offshore Brazil with progressively apparent younger ages eastward, which has been interpreted as the track of the Trindade Plume (Thompson et al, 1998;Skolotnev et al, 2011;Bongiolo et al, 2015;Santos, 2016;Santos et al 2018a,b;Skolotnev and Peive, 2017;Maia et al, 2021). Although many geochemical and some geochronological studies have been carried out so far on the main islands of this alignment (Trindade and Martin Vaz; e.g., Halliday et al, 1992;Marques et al, 1999;Siebel et al, 2000;Bongiolo et al 2015;Santos et al 2018aSantos et al , 2018b, both the precise age progression rate along the VTR and an understanding of the nature of each of the magmatic episodes remain elusive, mainly due to the sparse data available for the seamounts (Skolotnev et al, 2011;Peyve and Skolotnev, 2014;Santos, 2016;Skolotnev and Peive, 2017;Jesus et al, 2019;Maia et al, 2021).…”

“…To provide further information on the alkaline magmatism of the Vitória-Trindade Ridge, we here present new geochronological and isotopic data of samples from the volcanic episode that led to the formation of one of the largest physiographic features of the VTR alignment, the Davis Bank. We report new 40 Ar/ 39 Ar age data, Sr-Nd-Pb isotopic compositions and geochemical compositions from Davis Bank in combination with literature data (Halliday et al, 1992, Marques et al, 1999, Fodor and Hanan, 2000Siebel et al, 2000;Peyve and Skolotnev, 2014;Bongiolo et al, 2015;Skolotnev and Peive, 2017;Santos et al, 2018a;Jesus et al, 2019;Maia et al, 2021) to elaborate a petrogenetic model that explains the isotopic signature of the studied rocks, as well as to discuss the associated tectonic settings.…”

“…36-57 wt.%; MgO ca. 10-15 wt.%) (Marques et al, 1999(Marques et al, , 2016Bongiolo et al, 2015;2018a, 2018b.…”