Abstract
Paradoxically, the lists of “proxies” of both plate- and plume-related settings are devoid of even a mention of the high-grade metamorphic rocks (granulite, amphibolite and high-temperature eclogite facies). However, the granulite-gneiss belts and areas which contain these rocks, have a regional distribution in both the Precambrian and the Phanerozoic records. The origin and evolution of the granulite-gneiss belts correspond to the activity of plumes expressed in vigorous heating of the continental crust; intraplate magmatism; formation of rift depressions filled with sediments, juvenile lavas, and pyroclastic flow deposits; and metamorphism of lower and middle crustal complexes under conditions of granulite and high-temperature amphibolite facies that spreads over the fill of rift depressions also. Granulite-gneiss complexes of the East European Craton form one of the main components of the large oval intracontinental tectonic terranes of regional or continental rank. Inclusion of the granulite-gneiss complexes from Eastern Europe, North and South America, Africa, India, China and Australia in discussion of the problem indicated in the title to this paper, suggests consideration of a significant change in existing views on the relations between the plate- and plume-tectonic processes in geological history, as well as in supercontinent assembly and decay. The East European and North American cratons are fragments of the long-lived supercontinent Lauroscandia. After its appearance at ~2.8 Ga, the crust of this supercontinent evolved under the influence of the sequence of powerful mantle plumes (superplumes) up to ~0.85 Ga. During this time Lauroscandia was subjected to rifting, partial breakup and the following reconstruction of the continent. The processes of plate-tectonic type (rifting with the transition to spreading and closing of the short-lived ocean with subduction) within Lauroscandia were controlled by the superplumes. Revision of the nature of the granulite-gneiss complexes has led to a fundamental new understanding of: a more important role than envisaged previously for mantle-plume processes in the juvenile additions to the continental crust, especially during the Neoarchaean-Proterozoic; the existence of the supercontinent Lauroscandia from ~2.80 to 0.85 Ga; the leading role of mantle plumes in the interaction of plate- and plume-tectonics in the Neoarchaean-Proterozoic history of Lauroscandia and perhaps of the continental crust as a whole. We propose that the evolution of the geodynamic settings of the Earth’s crust origin can be represented as a spiral sequence: the interaction of mantle-plume processes and embryonic microplate tectonics during the Palaeo-Mezoarchaean (~3.8–2.8 Ga) → plume-tectonics and local plume-driven plate-tectonics (~2.80–0.55 Ga) → Phanerozoic plate tectonics along with a reduced role of mantle plumes.
Highlights
The direct observations of geological processes on the modern Earth, as well as the data from the Mesozoic-Cenozoic record were the starting points for the creation and development of the plate-tectonics model that was initially defined in a series of papers between the late 1950s and early 1960s [e.g., Dietz, 1961; Hess, 1962; Wilson, 1963]
The Proterozoic tectonic history of the Queen Maud Block of Arctic Canada includes: (1) widespread magmatism derived from Neoarchaean source rocks 2.50– 2.46 Ga ago, (2) the origin of a sedimentary belt dated at 2.44–2.39 Ga and containing detritus 2.50–2.45 Ga in age, and (3) ~2.39 Ga regional granulite-facies metamorphism [Schultz et al, 2007]
We have listed only the prominent examples, which display (1) systematic links of Large Igneous Provinces (LIPs), and of formation history of intracontinental sedimentary basins and granulite-facies metamorphism, to peak U–Pb zircon ages of juvenile rocks; and (2) synchronism of these phenomena in almost all continents. These two sets of circumstances cannot be explained by plate-tectonic reconstructions and presuppose the existence of a large Neoarchaean–Palaeoproterozoic supercontinent like that suggested by Piper [2015] on the basis of recent paleomagnetic data
Summary
The direct observations of geological processes on the modern Earth, as well as the data from the Mesozoic-Cenozoic record were the starting points for the creation and development of the plate-tectonics model that was initially defined in a series of papers between the late 1950s and early 1960s [e.g., Dietz, 1961; Hess, 1962; Wilson, 1963]. In addition to granulite-gneiss complexes, the intracontinental oval orogens comprise juvenile and crust-contaminated mafic igneous rocks, layered mafic-ultramafic intrusions, ‘dry’, high-temperature within-plate granites, enderbites and charnockites, as well as low-grade sedimentary-volcanic belts. In addition to the granulite-gneiss complexes and associated intrusions, juvenile complexes are concentrated within volcanic-sedimentary and volcanic-plutonic belts composed of low-grade metamorphic rocks of greenschist to low-temperature amphibolite facies These belts can be interpreted largely as former continental rifts, some fragments of which are similar to modern sutures and include riftogenic, and oceanic and island-arc complexes formed in shortlived oceans of the Red Sea type (e.g., Pechenga– Varzuga, Circum-Karelian, Circum-Superior, TransHudson and other Palaeoproterozoic belts). The granulite-gneiss belts are distinct intracontinental tectonic structures composed of sedimentary and igneous rocks undergoing high-grade metamorphism These belts are a characteristic component of plume-related intracontinental oval orogens [Mints, 2015b, 2015c]. SUGGESTED CO-EXISTENCE AND INTERACTION OF PLUME- AND EMBRYONIC PLATE-TECTONICS (3.8-3.5 GA)
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