Pb, Nd, and Sr Isotope Mapping of Grenville‐Age Crustal Provinces in Rodinia

Wareham, Christopher D.; Pankhurst, R. J.; Thomas, Robert J.; Storey, B. C.; Grantham, G.H.; Jacobs, J. Bruce; Eglington, B. M.

doi:10.1086/516051

Cited by 96 publications

(61 citation statements)

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“…Rodinian reconstructions suggest that the Falkland Islands were situated east of South Africa at a latitude similar to that of the samples reported here (African framework for the reconstruction) (Jacobs et al, 1999;Wareham et al, 1998). If these reconstructions are correct, then the older protolith evident in the Bushmanland Sub-province of Namaqualand and the sub-Karoo boreholes must terminate before reaching either the Mesoproterozoic exposures in Natal or the reconstructed position of the Cape Meredith Complex.…”

Section: Discussionsupporting

confidence: 70%

“…The geochronological and isotopic evolution of crust in the Namaqua-Natal Belt is dominated by mantle extraction events at ∼2 and 1.4 Ga (Rogers and Hawkesworth, 1982;Barton, 1983;Eglington et al, 1989;Thomas and Eglington, 1990;Thomas et al, 1993;Clifford et al, 1995;Reid, 1997;Reid et al, 1997;Wareham et al, 1998;Robb et al, 1999; and references quoted therein). This two-stage evolution is well illustrated on plots of initial 87 Sr/ 86 Sr relative to date (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Geochronological and isotopic constraints on the Mesoproterozoic Namaqua–Natal Belt: evidence from deep borehole intersections in South Africa

Eglington

Armstrong

2003

Precambrian Research

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Geochronological and isotopic constraints on the Mesoproterozoic Namaqua–Natal Belt: evidence from deep borehole intersections in South Africa

Eglington

Armstrong

2003

Precambrian Research

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“…The possibilities of correlations with the coeval terranes of the Islas Malvinas (Falkland Islands: Cingolani and Varela, 1976;Thomas et al, 1998;Wareham et al, 1998;Jacobs et al, 1999), the Mesoproterozoic belt of Uruguay (Preciozzi et al, 1999), as well as the Sunsas belt of the South American Amazon Craton (Sadowski and Bettencourt, 1996;Sato and Tassinari, 1997) or the Brazilian coastal and southern regions (Sato, 1998) have not yet been clarified.…”

Section: Discussionmentioning

confidence: 99%

The Las Matras tonalitic–trondhjemitic pluton, central Argentina: Grenvillian-age constraints, geochemical characteristics, and regional implications

Sato

Tickyj

Llambías

et al. 2000

Journal of South American Earth Sciences

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The N-S trending belt with Grenvillian-age rocks developed in central western Argentina represents the basement of an allochthonous terrane derived from Laurentia during the Early Paleozoic. The Las Matras pluton (36Њ46 H S, 67Њ07 H W) is located at the southern extension of this belt in the Las Matras Block. It consists of a low-Al tonalitic to trondhjemitic facies characteristic of an arc magmatism. Isotopic studies yielded Grenvillian Rb-Sr (1212^47 Ma) and Sm-Nd (1188^47 Ma) ages which, due to the undeformed and non-metamorphosed character of the pluton, are interpreted to represent a crystallization age of around 1200 Ma. Although this age is slightly older than available dates from other exposures of the same belt, and the undeformed feature is also distinctive for Las Matras, the depleted Sr and Nd isotopic signatures of the pluton agree with those from other magmatic rocks involved in that belt. The differences found between Las Matras and the northern exposures indicate that this belt with Grenvillian-age rocks comprises regions of non-homogeneous evolution. Although the correlation of the Lower Paleozoic platform carbonates from the sedimentary cover of the Grenvillian-age basement rocks suggests the surroundings of the Southern Grenville Province (Texas and northern Mexico) as the probable detachment site for the Argentine belt, comparison of magmatic and tectonic processes involved in these basement rocks does not indicate similar evolutions. This fact can suggest an independent evolution of the Argentine belt prior to amalgamation to the Laurentian Grenville orogen. ᭧

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“…These rocks have not been accurately dated, but the lithologies (gneiss, granitoids) and isotopic compositions are similar to those found in the Mesoproterozoic (c. 1.1 Ga) Cape Meredith Complex, which is exposed on the southern tip of West Falkland (Wareham et al 1998;Jacobs et al 1999;Thomas et al 2000). They were formed within a Grenville-age juvenile island arc which extended from southern Africa through the Falkland region and into East Antarctica (Wareham et al 1998;Thomas et al 2000). Gneissic continental basement rocks have also been found in dredge hauls along the top of the Falkland Escarpment, although such hauls also include basaltic rocks (Lorenzo & Mutter 1988;Lorenzo & Wessel 1997).…”

Section: Basementmentioning

confidence: 92%

The three-dimensional lithospheric structure of the Falkland Plateau region based on gravity modelling

Kimbell

Richards

2008

JGS

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Abstract:The lithospheric structure of the Falkland Plateau region has been modelled by making an initial estimate on the basis of local isostasy and then refining the geometries by inversion of gravity anomalies. The model predicts a crustal thickness beneath the Falkland Plateau Basin that is more than twice that previously inferred from seismic evidence. The preferred explanation is that the seismic survey detected high-velocity (?underplated) lower crust rather than upper mantle. This is compatible with the results of deep seismic experiments over the conjugate Filchner Block of Antarctica and also appears likely on the basis of the position of the Falkland Plateau Basin in relation to the Karoo-Ferrar magmatic province at the time of extension. Continental crust is inferred to be continuous beneath the northern part of the Falkland Plateau, as there are consistent magnetic and flexural anomalies associated with the continent-ocean boundary. Flexural modelling of the southern margin of the plateau indicates lateral variations in strength, with the strongest lithosphere beneath the Falkland Plateau Basin. This may indicate thick oceanic crust beneath the southern part of the basin or the effect of thinning relatively weak continental crust and replacing it with relatively strong underplating. [End of Abstract]

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Pb, Nd, and Sr Isotope Mapping of Grenville‐Age Crustal Provinces in Rodinia

Cited by 96 publications

References 1 publication

Geochronological and isotopic constraints on the Mesoproterozoic Namaqua–Natal Belt: evidence from deep borehole intersections in South Africa

Geochronological and isotopic constraints on the Mesoproterozoic Namaqua–Natal Belt: evidence from deep borehole intersections in South Africa

The Las Matras tonalitic–trondhjemitic pluton, central Argentina: Grenvillian-age constraints, geochemical characteristics, and regional implications

The three-dimensional lithospheric structure of the Falkland Plateau region based on gravity modelling

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