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The Preserved Plume of the Caribbean Large Igneous Plateau Revealed by 3D Data-Integrative Models

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The Preserved Plume of the Caribbean Large Igneous Plateau Revealed by 3D Data-Integrative Models Solid Earth, 12, 275–298, 2021 https://doi.org/10.5194/se-12-275-2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. The preserved plume of the Caribbean Large Igneous Plateau revealed by 3D data-integrative models Ángela María Gómez-García1,2,3,z, Eline Le Breton4, Magdalena Scheck-Wenderoth1, Gaspar Monsalve2, and Denis Anikiev1 1GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany 2Facultad de Minas, Universidad Nacional de Colombia, Medellín, Colombia 3CEMarin – Corporation Center of Excellence in Marine Sciences, Bogotá, Colombia 4Institute of Geological Sciences, Freie Universität Berlin, 12249 Berlin, Germany zInvited contribution by Ángela María Gómez-García, recipient of the EGU Seismology Outstanding Student Poster and PICO Award 2019. Correspondence: Ángela María Gómez-García ([email protected]) Received: 4 September 2020 – Discussion started: 28 September 2020 Revised: 19 November 2020 – Accepted: 4 December 2020 – Published: 29 January 2021 Abstract. Remnants of the Caribbean Large Igneous Plateau tomography, at least down to 75 km depth. The interpreted (C-LIP) are found as thicker than normal oceanic crust in plume conduits spatially correlate with the thinner crustal re- the Caribbean Sea that formed during rapid pulses of mag- gions present in both basins; therefore, we propose a mod- matic activity at ∼ 91–88 and ∼ 76 Ma. Strong geochemi- ification to the commonly accepted tectonic model of the cal evidence supports the hypothesis that the C-LIP formed Caribbean, suggesting that the thinner domains correspond due to melting of the plume head of the Galápagos hotspot, to the centres of uplift due to the inflow of the hot, buoyant which interacted with the Farallon (Proto-Caribbean) plate plume head. Finally, using six different kinematic models, in the eastern Pacific. Considering plate tectonics theory, we test the hypothesis that the C-LIP originated above the it is expected that the lithospheric portion of the plume- Galápagos hotspot; however, misfits of up to ∼ 3000 km are related material migrated within the Proto-Caribbean plate in found between the present-day hotspot location and the man- a north–north-eastward direction, developing the present-day tle anomalies, reconstructed back to 90 Ma. Therefore, we Caribbean plate. In this research, we used 3D lithospheric- shed light on possible sources of error responsible for this scale, data-integrative models of the current Caribbean plate offset and discuss two possible interpretations: (1) the Galá- setting to reveal, for the first time, the presence of posi- pagos hotspot migrated (∼ 1200–3000 km) westward while tive density anomalies in the uppermost lithospheric man- the Caribbean plate moved to the north, or (2) the C-LIP was tle. These models are based on the integration of up-to- formed by a different plume, which – if considered fixed – date geophysical datasets from the Earth’s surface down would be nowadays located below the South American con- to 200 km depth, which are validated using high-resolution tinent. free-air gravity measurements. Based on the gravity resid- uals (modelled minus observed gravity), we derive density heterogeneities both in the crystalline crust and the upper- most oceanic mantle (< 50 km). Our results reveal the pres- 1 Introduction ence of two positive mantle density anomalies beneath the Oceanic plateaus are vast areas characterized by a thicker Colombian and the Venezuelan basins, interpreted as the pre- than “normal” oceanic crust, which might reach up to 38 km served fossil plume conduits associated with the C-LIP for- (Kerr and Mahoney, 2007). Although about 12 different mation. Such mantle bodies have never been identified be- oceanic plateaus have been recognized worldwide, they rep- fore, but a positive density trend is also indicated by S-wave resent one of the least well-known of Earth’s magmatic pro- Published by Copernicus Publications on behalf of the European Geosciences Union. 276 A. M. Gómez-García et al.: The preserved plume of the Caribbean Large Igneous Plateau cesses (Kerr, 2014). In the early 1970s, Edgar et al. (1971) the eastern Pacific. The present-day Caribbean plate is com- and Donnelly (1973) discovered the Caribbean Large Ig- posed of different accreted crustal domains (e.g. volcanic neous Plateau, which corresponds to the second largest arcs, continental and oceanic realms) that have migrated plateau (by area) after the Ontong Java Plateau, with an ap- since the Late Jurassic to Early Cretaceous period, including proximated extent of 1:1 × 106 km2 and an estimated excess the igneous plateau materials that affected the oceanic crust magma volume of 4:4 × 106 km3 (Kerr, 2014). of the former Farallon plate (Boschman et al., 2014; Montes The origin of such a vast volume of basalt is widely rec- et al., 2019a). ognized as the interaction of a mantle plume with the over- Different regions of the Caribbean have been the target of riding, mobile lithosphere. With time, the plume-related ma- relatively extensive seismic reflection and refraction, sonar, terial suffers physical and chemical changes, which at the and drilling campaigns (e.g. Diebold and Driscoll, 1999; same time are associated with a diversification in the way Edgar et al., 1971; Kroehler et al., 2011; Mauffret and Leroy, the plume interacts with the overriding plate. During the 1997; Rosencrantz, 1990); some of which were undertaken lifespan of a plume it is expected to first create extensive with the limitations of early seismic acquisition technol- oceanic plateaus, followed by aseismic ridges, due to melt- ogy. Nonetheless, the coverage of these measurements is ing of the large plume head or the narrower plume tail, re- poor when compared with the complexity of most of the spectively (Campbell, 2005). The initial stages of the plume– Caribbean morphological structures. lithosphere interaction include the uplift and weakening of In this paper, the main goal is to evaluate the present- the overlying lithosphere due to the inflow of hot, highly day 3D lithospheric structure of the South Caribbean mar- buoyant mantle material. At a later stage, when the plume gin (continental and oceanic domains – black box in Fig. 1) is no longer active, geodynamic models show that the frozen by means of modelling of the gravity anomalies (Gz), which plume material can be preserved into the lithosphere, form- are especially sensitive to deep density distributions (Ál- ing high-density and therefore high-velocity bodies (François varez et al., 2014, 2015) and are therefore a potential tool et al., 2018). for analysing the upper 200 km of the Earth. Here, the high Successful detections of present-day mantle plumes us- spatial resolution EIGEN6C-4 dataset is used (Förste et al., ing P-wave and/or S-wave velocity anomalies include the 2014; Ince et al., 2019), which includes a spherical harmonic work of, for example, Montelli et al. (2004) and Civiero solution of up to a degree and order of Nmax D 2190, equiv- et al. (2019). These results suggest that the currently active alent to a topographic wavelength of ∼ 18 km. plumes are characterized by negative velocity anomalies, as- Due to the fact that the gravity response of a system is the sociated with the presence of high-temperature material. The superposition of the gravity effects caused by all the density plume conduct shows a variety of shapes, some of which contrasts within it, we considered the gravitational effects include the interconnection of branches at different depths caused by the heterogeneous lithospheric mantle in the South (e.g. Civiero et al., 2019, and references therein). Imaging Caribbean and north-western South American plates. There- these complex systems, however, has posed a large challenge fore, the geometries of both the Nazca and the Caribbean flat in the scientific community, especially for the correct inter- slabs were included in the gravity models. pretation of tomographic images (Campbell, 2005; Civiero Previous studies in this region include few 3D et al., 2019). lithospheric-scale, gravity-validated models (Gómez- The oceanic plateaus are normally difficult to subduct due García et al., 2019b; Sanchez-Rojas and Palma, 2014). to their abnormal thickness and positive thermal imprint in- However, some limitations of these attempts include, for herited from their mantle plume origin. Thus, fragments of instance, a spatially heterogeneous gravity dataset, a mantle the Caribbean plateau have been accreted along continental that is considered to have a uniform and constant density, margins, such as in Ecuador, Colombia, Panama, Costa Rica, and that the analysis is of only the shallow density contrasts. Curaçao, and Hispaniola (Hastie and Kerr, 2010; Thomp- The results of the gravity inversion not only highlight son et al., 2004). Using accreted material and relatively few crustal areas heavily affected by the high-density plume ma- drilled or dragged submarine rock samples, the geochemistry terial but also suggest the presence of a high-density trend of the Caribbean Large Igneous Plateau (C-LIP) has been re- in the oceanic mantle of the Caribbean plate. This trend can constructed (e.g. Geldmacher et al., 2003; Hastie and Kerr, be followed from the Moho down to 75 km depth, as sup- 2010; Kerr and Tarney, 2005; Thompson et al., 2004). In- ported by high S-wave velocities in the tomographic model deed, strong geochemical evidence suggests that the C-LIP SL2013sv (Schaeffer and Lebedev, 2013). These results are corresponds to melting of the plume head of the Galápagos interpreted as the preserved, lithospheric fossil plume con- hotspot (Geldmacher et al., 2003; Thompson et al., 2004), duits, responsible for the development of the C-LIP, which although recent kinematic reconstructions of the Caribbean migrated as the Proto-Caribbean lithosphere moved from the do not allow us to trace back the location of the plate above eastern Pacific. the present-day location of the Galápagos plume (Boschman Finally, taking advantage of the more precise spatial loca- et al., 2014).
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