The contribution of the young Cretaceous Caribbean Oceanic Plateau to the genesis of late Cretaceous arc magmatism in the Cordillera Occidental of Ecuador

Primitive Magmas in the Early Central American Volcanic Arc System Generated by Plume-Induced Subduction Initiation

“…Via plots of 143 Nd/ 144 Nd vs. 206 Pb/ 204 Pb and 207 Pb/ 204 Pb, Allibon et al (2008) (Allibon et al, 2008). For references for the various fields (that is, DMM, HIMU, pelagic sediments and chert), see Allibon et al (2008).…”

“…Via plots of 143 Nd/ 144 Nd vs. 206 Pb/ 204 Pb and 207 Pb/ 204 Pb, Allibon et al (2008) (Allibon et al, 2008). For references for the various fields (that is, DMM, HIMU, pelagic sediments and chert), see Allibon et al (2008). The field for the Galapagos Plume at 90 Ma is from Hauff et al (2000b) and the isotope data for Sona-Azuero, Golfito and Chagres Bayano are from Hauff et al (2000a), Lissinna (2005) and Wegner et al (2011).…”

“…These Ecuadorian arc sequences are ones considered by Whattam and Stern (2015) to represent the same plume-induced volcanic arc activity as in Central America. Using the 143 Nd/ 144 Nd vs. 206 Pb/ 204 Pb plot of Allibon et al (2008), I show in Figure 12 that formation of both CAVAS lavas and the CLIP require mixing of the same three components. Allibon et al (2008) suggested that an average contribution of 12-15% HIMU, 7-15% sediments and chert and 70-75% DMM is required to explain the Pb and Nd isotopic values.…”

“…Using the 143 Nd/ 144 Nd vs. 206 Pb/ 204 Pb plot of Allibon et al (2008), I show in Figure 12 that formation of both CAVAS lavas and the CLIP require mixing of the same three components. Allibon et al (2008) suggested that an average contribution of 12-15% HIMU, 7-15% sediments and chert and 70-75% DMM is required to explain the Pb and Nd isotopic values. Allibon et al (2008) further suggested that an anomalously high thermal regime responsible for such high proportions of HIMU was likely inherited from the CLIP which supports the idea of an elevated thermal regime at subduction inception.…”

Late Cretaceous felsic intrusions in oceanic plateau basalts in SW Ecuador: Markers of subduction initiation?

“…Rocks from the southern limit of the CLIP in SW Ecuador include: 1) basalts, dolerites and gabbros typical of plateau settings with ages ranging between 90 Ma and 85 Ma (Kerr et al, 2002a;Luzieux et al, 2006;Vallejo et al, 2009Vallejo et al, , 2006, an interval that coincides with the major pulse of CLIP magmatic activity and with the supposed plume-induced subduction initiation at the margins of the CLIP, and 2) Late Cretaceous intrusive and volcanoclastic deposits (with ages also roughly coincident with the suggested subduction initiation beneath the CLIP) that have geochemical affinities that may relate them to a juvenile subduction setting (see also the bachelors thesis of Macias, 2018). However, various works in southwest and central Ecuador (Allibon et al, 2008;Amórtegui et al, 2011;van Melle et al, 2008) suggest that similar geochemical characteristics may result from the partial melting of the base of the oceanic plateau. Farther north, in the Western Cordillera of Ecuador, La Portada 4 Unit assigned to the base of the Rio Cala island arc (Kerr et al, 2002a;van Thournout, 1991;Wilkinson, 1998) and the Pujilí Granite (PG in Fig.…”