scholarly journals The Mid-Variscan Allochthon: Keys from correlation, partial retrodeformation and plate-tectonic reconstruction to unlock the geometry of a non-cylindrical belt

2021 ◽  
pp. 103700
Author(s):  
José R. Martínez Catalán ◽  
Karel Schulmann ◽  
Jean-François Ghienne
2010 ◽  
Author(s):  
Matt Luheshi ◽  
Keith Nunn ◽  
David Roberts ◽  
Hamish Wilson

2021 ◽  
Vol 9 ◽  
Author(s):  
Christian Vérard

The formation of Gondwana results from a complex history, which can be linked to many orogenic sutures. The sutures have often been gathered in the literature under broad orogenies — in particular the Eastern and Western Pan-African Orogenies — although their ages may vary a lot within those wide belts. The Panalesis model is a plate tectonic model, which aims at reconstructing 100% of the Earth’s surface, and proposes a geologically, geometrically, kinematically, and geodynamically coherent solution for the evolution of the Earth from 888 to 444 Ma. Although the model confirms that the assembly of Gondwana can be considered complete after the Damara and Kuunga orogenies, it shows above all that the detachment and amalgamation of “terranes” is a roughly continuous process, which even persisted after the Early Cambrian. By using the wealth of Plate Tectonics, the Panalesis model makes it possible to derive numerous additional data and maps, such as the age of the sea-floor everywhere on the planet at every time slice, for instance. The evolution of accretion rates at mid-oceanic ridges and subduction rates at trenches are shown here, and yields results consistent with previous estimates. Understanding the variation of the global tectonic activity of our planet through time is key to link plate tectonic modeling with other disciplines of Earth sciences.


2014 ◽  
Vol 6 (1) ◽  
pp. 793-830
Author(s):  
J. Cannon ◽  
E. Lau ◽  
R. D. Müller

Abstract. We describe a novel method implemented in the GPlates plate tectonic reconstruction software to interactively reconstruct arbitrarily high-resolution raster data to past geological times using a rotation model. The approach is based on the projection of geo-referenced raster data into a cube map followed by a reverse projection onto rotated tectonic plates on the surface of the globe. This decouples the rendering of a geo-referenced raster from its reconstruction, providing a number of benefits including a simple implementation and the ability to combine rasters with different geo-referencing or inbuilt raster projections. The cube map projection is accelerated by graphics hardware in a wide variety of computer systems manufactured over the last decade. Furthermore, by integrating a multi-resolution tile partitioning into the cube map we can provide on-demand tile streaming, level-of-detail rendering and hierarchical visibility culling enabling researchers to visually explore essentially unlimited resolution geophysical raster data attached to tectonic plates and reconstructed through geological time. This capability forms the basis for interactively building and improving plate reconstructions in an iterative fashion, particularly for tectonically complex regions.


Author(s):  
Spencer Fuston ◽  
Jonny Wu

The configuration of mid-ocean ridges subducted below North America prior to Oligocene time is unconstrained by seafloor isochrons and has been primarily inferred from upper-plate geology, including near-trench magmatism. However, many tectonic models are permitted from these constraints. We present a fully kinematic, plate tectonic reconstruction of the NW Cordillera since 60 Ma built by structurally unfolding subducted slabs, imaged by mantle tomography, back to Earth’s surface. We map in three-dimensions the attached Alaska and Cascadia slabs, and a detached slab below western Yukon (Canada) at 400−600 km depth that we call the “Yukon Slab.” Our restoration of these lower plates within a global plate model indicates the Alaska slab accounts for Pacific-Kula subduction since ca. 60 Ma below the Aleutian Islands whereas the Cascadia slab accounts for Farallon subduction since at least ca. 75 Ma below southern California, USA. However, intermediate areas show two reconstruction gaps that persist until 40 Ma. We show that these reconstruction gaps correlate spatiotemporally to published NW Cordillera near-trench magmatism, even considering possible terrane translation. We attribute these gaps to thermal erosion related to ridge subduction and model mid-ocean ridges within these reconstruction gap mid-points. Our reconstructions show two coeval ridge-trench intersections that bound an additional “Resurrection”-like plate along the NW Cordillera prior to 40 Ma. In this model, the Yukon slab represents a thermally eroded remnant of the Resurrection plate. Our reconstructions support a “northern option” Farallon ridge geometry and allow up to ∼1200 km Chugach terrane translation since Paleocene time, providing a new “tomographic piercing point” for the Baja-British Columbia debate.


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