Evaluation of Paleomagnetic Bias in Ediacaran Global Paleogeographic Reconstructions

Wu, Longmin; Murphy, J. Brendan; Nance, R. Damian

doi:10.1029/2022gl100405

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…The example described here, with thick volcano-related deposits controlled by fault activity, fits better with an extensional setting, also compatible with the extensional faults of the same age described in the Canigó massif [43] and with the drastic changes in thickness and facies of the El Baell and Estana formations. This extensional scenario could be linked to the break-up of Gondwana and the birth of intervening oceans, in a pivotal time interval between the end of Neoproterozoic-Early Cambrian (Cadomian) accretionary tectonics and the Cambrian-Ordovician opening of the Rheic Ocean [87][88][89][90].…”

Section: Regionalmentioning

confidence: 99%

Reconstructing a Super-Eruption From the Upper Ordovician Period in the Eastern Pyrenees, Spain

Marti,

Casas,

Muñoz

2024

Lithosphere

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The Pyrenean basement rocks, NE of the Iberian Peninsula, southwestern Europe, include evidence of several pre-Variscan magmatic episodes which indicate the complex geodynamic history of this segment of the northern Gondwana margin from late Neoproterozoic to Early-Palaeozoic times. One of the most significant magmatic episodes was late Mid-early Upper Ordovician (Darriwilian-Katian) age that produced several granitic bodies and volcanic rocks interbedded with Sandbian-Katian sediments. This magmatism is well represented in the Ribes de Freser area (Freser valley, Bruguera and Campelles localities, eastern Pyrenees), where these Ordovician magmatic rocks were affected by an irregularly distributed Variscan deformation and mainly by severe Alpine tectonics, which originated the superposition of several structural units. We present a palinspatic reconstruction of this Alpine deformation (80-20 Ma), that permitted us to infer the geometry, facies distribution, original position, thickness, and significance of these volcanic rocks. This reconstruction allows us to interpret the volcanic rocks cropping out at the Freser valley, Bruguera, and Campelles areas as intra-caldera deposits representing a minimum preserved volume of the order of 100 km3. This may confirm the existence of super-eruptions of Upper-Ordovician age in that sector of the eastern Pyrenees and emphasizes the extent of the Upper-Ordovician felsic volcanism in this sector of the northern Gondwana margin, probably developed in an extensional scenario linked to the development of the Rheic Ocean during Gondwana margin breakup.

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Section: Regionalmentioning

confidence: 99%

Reconstructing a Super-Eruption From the Upper Ordovician Period in the Eastern Pyrenees, Spain

Marti,

Casas,

Muñoz

2024

Lithosphere

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Does the Ollo de Sapo magmatic event support Furongian‒Tremadocian mantle plume activity fringing NW Gondwana?

Casas,

Murphy,

Díez Montes

et al. 2023

International Geology Review

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The provenance of Avalonia and its tectonic implications: a critical reappraisal

Murphy

Nance

2023

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The late Neoproterozoic-Cambrian interval is characterized by global-scale orogenesis, rapid continental growth, and profound changes in Earth systems. Orogenic activity involved continental collisions spanning more than 100 million years, culminating in Gondwana amalgamation. Avalonia is an example of arc magmatism and accretionary tectonics as subduction zones re-located to Gondwana's periphery in the aftermath of those collisions, and its evolution provides significant constraints for global reconstructions. Comprising late Neoproterozoic (ca. 650-570 Ma) arc-related magmatic and metasedimentary rocks, Avalonia is defined as a composite terrane by its latest Ediacaran-Ordovician overstep sequence; a distinctive, siliciclastic-dominated cover bearing “Acado-Baltic” fauna. This definition implies Neoproterozoic Avalonia may consist of several terranes, and so precise paleomagnetic or provenance determination in one locality need not apply to all. On the basis of detrital zircon and Nd isotopic data, Avalonia and other lithotectonically-related terranes such as Cadomia, have long been thought to have resided along the Amazonian-West African margin of Gondwana between ∼650-500 Ma, Avalonia connected to Amazonia, and Cadomia to West Africa. These interpretations have constrained Paleozoic reconstructions; many imply the departure of several peri-Gondwanan terranes led to the Early Paleozoic development of the Rheic Ocean whose subsequent demise in the late Paleozoic led to Pangea amalgamation. Since these ideas were proposed, several new lines of evidence have challenged the Amazonian affinity of Avalonia. First, there is evidence that some Avalonian terranes may have been “peri-Baltican” during the Neoproterozoic. Baltica was originally excluded as a potential source for Avalonia because, unlike Amazonia, arc-related Neoproterozoic rocks were not documented. However, subsequent recognition of Ediacaran arc-related sequences in the Timanides of northeastern Baltica invalidates this assumption. Second, detailed paleontological and lithostratigraphic studies have been interpreted to reflect an insular Avalonia, well removed from either Gondwana or Baltica during the Ediacaran and early Cambrian. Third, recent paleomagnetic data have raised the possibility of an ocean (Clymene Ocean) between Amazonia and West Africa in the late Neoproterozoic, thereby challenging conventional reconstructions that show the “peri-Gondwanan” terranes as a contiguous belt straddling the suture zone between these cratons. In this contribution, we critically re-evaluate the provenance of the so-called “peri-Gondwanan” terranes, the contiguity of the so-called “Avalonian-Cadomian” belt, and the validity of the various plate tectonic models based on the traditional interpretation of these terranes. In addition, we draw attention to critical uncertainties and the challenges that lie ahead.

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Evaluation of Paleomagnetic Bias in Ediacaran Global Paleogeographic Reconstructions

Cited by 3 publications

References 34 publications

Reconstructing a Super-Eruption From the Upper Ordovician Period in the Eastern Pyrenees, Spain

Reconstructing a Super-Eruption From the Upper Ordovician Period in the Eastern Pyrenees, Spain

Does the Ollo de Sapo magmatic event support Furongian‒Tremadocian mantle plume activity fringing NW Gondwana?

The provenance of Avalonia and its tectonic implications: a critical reappraisal

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