scholarly journals Asthenospheric zircon below Galápagos dates plume activity

2021 ◽  
Author(s):  
Yamirka Rojas-Agramonte ◽  
Boris Kaus ◽  
Andrea Piccolo ◽  
Ian Williams ◽  
Axel Gerdes ◽  
...  
Keyword(s):  
Mantle Plume ◽  
Numerical Experiments ◽  
Lithospheric Plate ◽  
Plate Motion ◽  
South American ◽  
Plume Dynamics ◽  
Tectonic Settings ◽  
The Caribbean ◽  
Galapagos Plume ◽  
Stable Domains

Abstract Mantle plumes are active for long periods of time1,2, however dating the onset of their activity is difficult. The magmatic products of the Galápagos plume, for example, have been subducted and fragmentarily accreted to the Caribbean and South American plates3,4. Based on submarine and terrestrial exposures it is inferred that the plume has been operating for ~90 Myrs5 or perhaps even longer (e.g., ~139 Myrs6). Here we show that the activity of the plume dates back to ~170 Ma. Evidence for this comes from 0 to 168 Ma zircon with isotopic plume signature (Galápagos Plume Array; GPA) recovered from lavas and sediments from ten islands of the archipelago. Given lithospheric plate motion, this result implies that GPA zircon predating the Galápagos lithosphere (i.e., >14 Ma) formed at asthenospheric depths. Thermo-mechanical numerical experiments of plume-lithosphere interaction show that old zircon grains can be stored within local astenospheric stable domains to be later captured by subsequent rising plume magmas. These results open new avenues for research on mantle plume dynamics in similar tectonic settings.

scholarly journals Hot Times in Tectonophysics: Mantle Plume Dynamics and Magmatic Perturbances

2020 ◽  
Vol 11 (2) ◽  
pp. 19
Author(s):  
Vrishin R. Soman
Keyword(s):  
Mantle Plume ◽  
Lithospheric Plate ◽  
Plate Motion ◽  
Magmatic Fluid ◽  
Mantle Flow ◽  
Plate Boundaries ◽  
Mantle Plumes ◽  
Plate Model ◽  
Plate Motions ◽  
Plume Model

Earth’s dynamic lithospheric (plate) motions often are not obvious when considered in relation to the temporal stability of the crust. Seismic radiology experiments confirm that the extreme pressures and temperatures in the mantle, and to a lesser extent the asthenosphere, result in a heterogeneously viscous rheology. Occasionally, magmatic fluid makes its way through the lithospheric plate to the surface, appearing typically as a volcano, fissure eruption, or lava flow. When occurring away from the edges of plate boundaries, these long-lasting suppliers of lava, present over millions of years, are called mantle plumes, or ‘hotspots.’ Conventional definitions of mantle plumes note that they are stationary with respect to each other and the motion of the plates, passively tracing historical plate motion in volcanic formations such as the Hawaiian-Emperor island arc – the Plate Model. In this model, mantle plumes primarily occur as a consequence of lithospheric extension.Recent empirical studies, however, have demonstrated that hotspots are not as geographically consistent as previously thought. They may move in relation to each other, as well as contribute actively toward lithospheric plate motions – the Plume Model. There is a lively, ongoing debate between the Plate and Plume hypotheses, essentially seeking to determine if mantle flow is merely a passive reaction to lithospheric plate motion (Plate Model), or whether plume activity in part drives this motion (Plume Model). More likely, it is a combination of passive and active mantle plume components that better describe the comprehensive behavior of these important and distinctive landscape forming features.

The preserved plume conduits of the Caribbean Large Igneous Plateau and their relation with the Galápagos hotspot back to 90 Ma

2021 ◽  
Author(s):  
Angela Maria Gomez Garcia ◽  
Eline Le Breton ◽  
Magdalena Scheck-Wenderoth ◽  
Gaspar Monsalve ◽  
Denis Anikiev
Keyword(s):  
Reference Frames ◽  
Thermal Anomaly ◽  
Caribbean Region ◽  
Positive Density ◽  
South American ◽  
Kinematic Models ◽  
Tomographic Data ◽  
The Caribbean ◽  
Moho Depths ◽  
South American Continent

<p>Remnants of the Caribbean Large Igneous Plateau (C-LIP) are found as thickened zones of oceanic crust in the Caribbean Sea, that formed during strong pulses of magmatic activity around 90 Ma. Previous studies have proposed the Galápagos hotspot as the origin of the thermal anomaly responsible for the development of this igneous province. Particularly, geochemical signature relates accreted C-LIP fragments along northern South America with the well-known hotspot material.</p><p>In this research, we use 3D lithospheric-scale structural and density models of the Caribbean region, in which up-to-date geophysical datasets (i.e.: tomographic data, Moho depths, sedimentary thickness, and bathymetry) have been integrated. Based on the gravity residuals (modelled minus observed EIGEN6C-4 dataset), we reconstruct density heterogeneities both in the crust and the uppermost oceanic mantle (< 50km).</p><p>Our results suggest the presence of two positive mantle density anomalies in the Colombian and the Venezuelan basins, interpreted as the preserved plume material which migrated together with the Proto-Caribbean plate from the east Pacific. Such bodies have never been identified before, but a positive density trend is also observed in the mantle tomography, at least down to 75 km depth.</p><p>Using recently published regional plate kinematic models and absolute reference frames, we test the hypothesis of the C-LIP origin in the Galápagos hotspot. However, misfits of up to ~3000 km between the present hotspot location and the mantle anomalies, reconstructed back to 90 Ma, is observed, as other authors reported in the past.</p><p>Therefore, we discuss possible sources of error responsible for this offset and pose two possible interpretations: 1. The Galápagos hotspot migrated (~1200-3000 km) westward while the Proto-Caribbean moved to the northeast, or 2. The C-LIP was formed by a different plume, which – if considered fixed - would be nowadays located below the South American continent.</p>

Linking the Wrangellia Flood Basalts to the Galápagos Hotspot

2021 ◽  
Author(s):  
J. Gregory Shellnutt ◽  
Jaroslav Dostal ◽  
Tung-Yi Lee
Keyword(s):  
Mantle Plume ◽  
Elevated Temperatures ◽  
Volcanic Rocks ◽  
Thermal Conditions ◽  
Internal Variability ◽  
Eastern Pacific ◽  
Unique Region ◽  
Elemental Ratios ◽  
Trace Elemental ◽  
The Caribbean

Abstract The Triassic volcanic rocks of Wrangellia erupted at an equatorial to tropical latitude that was within 3000 km of western North America. The mafic and ultramafic volcanic rocks are compositionally and isotopically similar to those of oceanic plateaux that were generated from a Pacific mantle plume-type source. The thermal conditions, estimated from the primitive rocks, indicate that it was a high temperature regime (T P > 1550°C) consistent with elevated temperatures expected for a mantle plume. The only active hotspot currently located near the equator of the eastern Pacific Ocean that was active during the Mesozoic and produced ultramafic volcanic rocks is the Galápagos hotspot. The calculated mantle potential temperatures, trace elemental ratios, and Sr-Nd-Pb isotopes of the Wrangellia volcanic rocks are within the range of those from the Caribbean Plateau and Galápagos Islands, and collectively have similar internal variability as the Hawaii-Emperor island chain. The paleogeographic constraints, thermal estimates, and geochemistry suggests that it is possible that the Galápagos hotspot generated the volcanic rocks of Wrangellia and the Caribbean plateau or, more broadly, that the eastern Pacific (Panthalassa) Ocean was a unique region where anomalously high thermal conditions either periodically or continually existed from ~230 Ma to the present day.

scholarly journals REVISIÓN TAXONÓMICA DEL CORAL PORITES COLONENSIS (SCLERACTINIA: PORITIDAE) EN EL CARIBE COLOMBIANO

2016 ◽  
Vol 37 (2) ◽  
Author(s):  
Dagoberto E. Venera Pontón ◽  
Javier Reyes ◽  
Guillermo Diaz Pulido
Keyword(s):  
Continental Shelf ◽  
Taxonomic Revision ◽  
Caribbean Sea ◽  
South American ◽  
Large Variability ◽  
Porites Astreoides ◽  
Taxonomic Review ◽  
Natural Park ◽  
The Caribbean ◽  
First Time

Porites colonensis is a coral from the Caribbean Sea; colonies are foliaceous, undulated, and plate-like. Polyps are dark brown or red with small bright white or green centers; pali are present in corallites and the septal plan is bisymmetrical, conformed by three fused ventral septa, a dorsal solitary septum, and two pairs of lateral septa at each side of the dorso-ventral axis. P. colonensis is similar and can be confused with the smooth varieties of Porites astreoides and Porites branneri. There are three specimens collected from Colombia and previously identified as P. colonensis: one from Golfo de Urabá (Darién ecoregion), other from Islas del Rosario (Coralline Archipelagos ecoregion), and another from an unspecified locality, in addition to one published observation from the Golfo de Urabá without collected specimens. A recent finding of other specimens in the Tayrona National Natural Park (TNNP, Tayrona ecoregion) and the absence of a rigorous taxonomic revision for all specimens collected from Colombia showed that it was necessary to review the presence and distribution of P. colonensis in the Colombian Caribbean. A taxonomic review was done for all specimens collected from Colombia and previously identified as P. colonensis. Then, the morphologic variability of specimens that were confirmed as P. colonensis was described. Only the specimens from TNNP agreed with the holotype description of P. colonensis, while others agreed with flat varieties of P. astreoides. Thus, the presence of P. colonensis is confirmed for the first time for Colombia, but its presence in other Colombian localities outside Tayrona ecoregion could not be demonstrated. This is the only confirmed record of this species for the South American continental shelf. Furthermore, the skeletal characteristics of Colombian P. colonensis corallites showed large variability, exceeding the ranges previously described for the species.

A Different Perspective for the Financial Crisis in Latin America and the Caribbean

1985 ◽  
Vol 27 (4) ◽  
pp. 9-20 ◽  
Author(s):  
João Clemente Baena Soares
Keyword(s):  
Financial Crisis ◽  
Latin American ◽  
External Debt ◽  
Central American ◽  
South American ◽  
External Financing ◽  
Entire Region ◽  
Goods And Services ◽  
The Caribbean ◽  
Interest Payments

The Latin American and Caribbean countries are facing a serious financial crisis. External debt in the region is over $360 billion, and seven South American countries are among the ten largest debtors in the world. Interest payments alone required, in the years of 1982, 1983, and 1984, more than 35% of total regional exports of goods and services, a percentage which reached the extreme level of over 50% for one country. To be sure, this problem mostly affects the largest economies, since most of the Central American and Caribbean countries apply to interest payments less than 20% of their exports. The debt problem is a reality for the entire region, and it makes it difficult for all the countries to obtain new external financing.

From Christian to Jew

2021 ◽  
pp. 27-45
Author(s):  
Laura Arnold Leibman
Keyword(s):  
Jewish Community ◽  
Caribbean Sea ◽  
People Of Color ◽  
South American ◽  
Crucial Step ◽  
The Caribbean ◽  
American Colony ◽  
The Right

The next crucial step in the siblings’ journey to gain the right to live and pray as they pleased came in 1811 when they moved to Suriname, a South American colony on the Caribbean Sea. In Suriname, Sarah and Isaac found their home among the largest multiracial Jewish community in the Americas and formally converted to Judaism. This community provided a spiritual home for Sarah and Isaac, but it also marked them as second-class citizens. Since their father, Abraham, had not married their mother, Surinamese law considered Sarah and Isaac people of color. This racial designation followed them into the synagogue, where they would sit separately from whites and couldn’t partake in synagogue honors. This chapter places the siblings’ experiences alongside that of other multiracial Jews who lived in Paramaribo at that time, highlighting their battles against oppression.

scholarly journals Causes and consequences of asymmetric lateral plume flow during South Atlantic rifting

2020 ◽  
Vol 117 (45) ◽  
pp. 27877-27883
Author(s):  
Jason P. Morgan ◽  
Jorge M. Taramón ◽  
Mario Araujo ◽  
Jörg Hasenclever ◽  
Marta Perez-Gussinye
Keyword(s):  
Mantle Plume ◽  
Numerical Experiments ◽  
Three Dimensional ◽  
South Atlantic ◽  
Continental Lithosphere ◽  
Rifted Margins ◽  
Plume Flow ◽  
Rifted Margin ◽  
Asymmetrically Distributed ◽  
Lateral Variations

Volcanic rifted margins are typically associated with a thick magmatic layer of seaward dipping reflectors and anomalous regional uplift. This is conventionally interpreted as due to melting of an arriving mantle plume head at the onset of rifting. However, seaward dipping reflectors and uplift are sometimes asymmetrically distributed with respect to the subsequent plume track. Here we investigate if these asymmetries are induced by preexisting lateral variations in the thickness of continental lithosphere and/or lithospheric stretching rates, variations that promote lateral sublithospheric flow of plume material below only one arm of the extending rift. Using three-dimensional numerical experiments, we find that South Atlantic rifting is predicted to develop a strong southward asymmetry in its distribution of seaward dipping reflectors and associated anomalous relief with respect to the Tristan Plume that “drove” this volcanic rifted margin, and that the region where plume material drains into the rift should experience long-lived uplift during rifting—both as observed. We conclude that a mantle plume is still needed to source the anomalously hot sublithospheric material that generates a volcanic rifted margin, but lateral along-rift flow from this plume, not a broad starting plume head, is what controls when and where a volcanic rifted margin will form.

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