Plate Tectonic Evolution of the Southern Margin of Laurussia in the Paleozoic

Orogenic plateaus have raised abundant attention amongst geoscientists during the last decades, offering unique opportunities to better understand the relationships between tectonics and climate, and their expression on the Earth’s surface.Orogenic plateau margins are key areas for understanding the mechanisms behind plateau (de)formation. Plateau margins are transitional areas between domains with contrasting relief and characteristics; the roughly flat elevated plateau interior, often with internally drained endorheic basins, and the external steep areas, deeply incised by high-discharge rivers. This thesis uses a wide range of structural and tectonic approaches to investigate the evolution of the southern margin of the Central Anatolian Plateau (CAP), studying an area between the plateau interior and the Cyprus arc. Several findings are presented here that constrain the evolution, timing and possible causes behind the development of this area, and thus that of the CAP. After peneplanation of the regional orogeny, abroad regional subsidence took place in Miocene times in the absence of major extensional faults, which led to the formation of a large basin in the northeast Mediterranean. Late Tortonian and younger contractional structures developed in the interior of the plateau, in its margin and offshore, and forced the inversion tectonics that fragmented the early Miocene basin into the different present-day domains. The tectonic evolution of the southern margin of the CAP can be explained based on the initiation of subduction in south Cyprus and subsequent thermo-mechanical behavior of this subduction zone and the evolving rheology of the Anatolian plate. The Cyprus slab retreat and posterior pull drove subsidence first by relatively minor stretching of the crust and then by its flexure. The growth by accretion and thickening of the upper plate, and that of the associated forearc basins system, caused by accreting sediments, led to rheological changes at the base of the crust that allowed thermal weakening, viscous deformation, driving subsequent surface uplift and raising the modern Taurus Mountains. This mechanism could be responsible for the uplifted plateau-like areas seen in other accretionary margins. ISBN: 978-90-9028673-0

Download Full-text

On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean

Science Advances ◽

10.1126/sciadv.1600022 ◽

2016 ◽

Vol 2 (7) ◽

pp. e1600022 ◽

Cited By ~ 16

Author(s):

Lydian M. Boschman ◽

Douwe J. J. van Hinsbergen

Keyword(s):

Triple Junction ◽

Tectonic Evolution ◽

Plate Boundary ◽

Pacific Plate ◽

Plate Tectonic ◽

Point Location ◽

Marine Magnetic Anomalies ◽

The Pacific ◽

History Of ◽

Ridge System

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea, and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. We show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests to a unique plate kinematic event that sparked the plate’s birth at virtually a point location, surrounded by the Izanagi, Farallon, and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization, which led to the birth of the Pacific Plate, and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable but migrating triple junction involving the gradual cessation of intraoceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of “Thalassa Incognita” that comprises the comprehensive Panthalassa Ocean surrounding Pangea.

Download Full-text

Precambrian tectonic evolution of Earth: an outline

South African Journal of Geology ◽

10.25131/sajg.124.0019 ◽

2021 ◽

Vol 124 (1) ◽

pp. 141-162 ◽

Cited By ~ 1

Author(s):

J.F. Dewey ◽

E.S. Kiseeva ◽

J.A. Pearce ◽

L.J. Robb

Keyword(s):

Tectonic Evolution ◽

Plate Tectonics ◽

Global Scale ◽

Sensu Stricto ◽

Strike Slip ◽

Small Scale ◽

Data Sets ◽

Crustal Material ◽

Plate Tectonic ◽

Single Plate

Abstract Space probes in our solar system have examined all bodies larger than about 400 km in diameter and shown that Earth is the only silicate planet with extant plate tectonics sensu stricto. Venus and Earth are about the same size at 12 000 km diameter, and close in density at 5 200 and 5 500 kg.m-3 respectively. Venus and Mars are stagnant lid planets; Mars may have had plate tectonics and Venus may have had alternating ca. 0.5 Ga periods of stagnant lid punctuated by short periods of plate turnover. In this paper, we contend that Earth has seen five, distinct, tectonic periods characterized by mainly different rock associations and patterns with rapid transitions between them; the Hadean to ca. 4.0 Ga, the Eo- and Palaeoarchaean to ca. 3.1 Ga, the Neoarchaean to ca. 2.5 Ga, the Proterozoic to ca. 0.8 Ga, and the Neoproterozoic and Phanerozoic. Plate tectonics sensu stricto, as we know it for present-day Earth, was operating during the Neoproterozoic and Phanerozoic, as witnessed by features such as obducted supra-subduction zone ophiolites, blueschists, jadeite, ruby, continental thin sediment sheets, continental shelf, edge, and rise assemblages, collisional sutures, and long strike-slip faults with large displacements. From rock associations and structures, nothing resembling plate tectonics operated prior to ca. 2.5 Ga. Archaean geology is almost wholly dissimilar from Proterozoic-Phanerozoic geology. Most of the Proterozoic operated in a plate tectonic milieu but, during the Archaean, Earth behaved in a non-plate tectonic way and was probably characterised by a stagnant lid with heat-loss by pluming and volcanism, together with diapiric inversion of tonalite-trondjemite-granodiorite (TTG) basement diapirs through sinking keels of greenstone supracrustals, and very minor mobilism. The Palaeoarchaean differed from the Neoarchaean in having a more blobby appearance whereas a crude linearity is typical of the Neoarchaean. The Hadean was probably a dry stagnant lid Earth with the bulk of its water delivered during the late heavy bombardment, when that thin mafic lithosphere was fragmented to sink into the asthenosphere and generate the copious TTG Ancient Grey Gneisses (AGG). During the Archaean, a stagnant unsegmented, lithospheric lid characterised Earth, although a case can be made for some form of mobilism with “block jostling”, rifting, compression and strike-slip faulting on a small scale. We conclude, following Burke and Dewey (1973), that there is no evidence for subduction on a global scale before about 2.5 Ga, although there is geochemical evidence for some form of local recycling of crustal material into the mantle during that period. After 2.5 Ga, linear/curvilinear deformation belts were developed, which “weld” cratons together and palaeomagnetism indicates that large, lateral, relative motions among continents had begun by at least 1.88 Ga. The “boring billion”, from about 1.8 to 0.8 Ga, was a period of two super-continents (Nuna, also known as Columbia, and Rodinia) characterised by substantial magmatism of intraplate type leading to the hypothesis that Earth had reverted to a single plate planet over this period; however, orogens with marginal accretionary tectonics and related magmatism and ore genesis indicate that plate tectonics was still taking place at and beyond the bounds of these supercontinents. The break-up of Rodinia heralded modern plate tectonics from about 0.8 Ga. Our conclusions are based, almost wholly, upon geological data sets, including petrology, ore geology and geochemistry, with minor input from modelling and theory.

Download Full-text