Pannotia: in defence of its existence and geodynamic significance

Murphy, J. Brendan; Nance, R. Damian; Cawood, Peter A.; Collins, William J.; Wei, Dan; Doucet, Luc S.; Heron, Philip J.; Li, Zheng‐Xiang; Mitchell, Ross N.; Pisarevsky, Sergei A.; Pufahl, Peir K.; Quesada, Cecilio; Spencer, Christopher J.; Strachan, Rob; Wu, Longmin

doi:10.1144/sp503-2020-96

Cited by 39 publications

(23 citation statements)

References 205 publications

(285 reference statements)

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“…In the following we assume that these thermochemical piles can persist at the core‐mantle boundary on billion‐year timescales (e.g., Jones et al., 2021; Yan et al., 2020); however, the outcome of the following model would not change if the source of the Kaavi‐Kuopio kimberlites was located in other deep Earth structures where plumes are generated. Despite the contention around LLSVP longevity and fixity, there is agreement for the role of mantle plumes, which emanated from the margins of LLSVPs or other lower mantle sources, in the emplacement of the contemporaneous CIMP and opening the Iapetus ocean (e.g., Ernst & Bell, 2010; Murphy et al., 2021; Robert et al., 2021; Tegner et al., 2019). We also advocate here for a role of these upwellings in the petrogenesis and geochemical evolution of the Kaavi‐Kuopio kimberlites (Figure 4; Figure 10).…”

Section: Discussionmentioning

confidence: 99%

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Dalton

Giuliani

Hergt

et al. 2022

Geochem Geophys Geosyst

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Despite the scientific and economic significance of kimberlites and related magmas, their origin is unclear. Here, we address this issue using whole‐rock and perovskite‐derived Sr‐Nd‐Hf isotopes for the three occurrences of kimberlite, lamproites and ultramafic lamprophyres (UMLs) in Finland. Mesoproterozoic olivine lamproites at Lentiira‐Kuhmo and UMLs at Kuusamo have different isotopic signatures yet were emplaced contemporaneously at 1,200 Ma in response to an extensional regime linked to the Baltica‐Laurentia breakup. The low εNd(i) and εHf(i) values of the olivine lamproites are consistent with an enriched subcontinental lithospheric mantle (SCLM) source while UML compositions are intermediate between those of typical kimberlites and lamproites and are interpreted to reflect mixing of asthenospheric melts and ∼10%–15% of melts sourced from metasomatized SCLM. The ∼750 Ma Kuusamo kimberlites, are probably linked to the mantle plume activity that initiated Rodinia's break‐up, exhibiting homogenous isotopic compositions which mirror the prominent Geodynamic and Source Constraints for ∼1,200 Ma Olivine Lamproite and Ultramafic Lamprophyre Magmatism in Eastern Finland (PREMA)‐like signature of kimberlites globally. By contrast, ∼620–585 Ma Kaavi‐Kuopio kimberlites show limited range in εNd(i) and 87Sr/86Sr(i) but have remarkably heterogeneous εHf(i) (+6.5 to −6.3) with a temporal trend toward lower εHf(i) values. While the Kuusamo kimberlites erupted during the early stage of continental break‐up, the Kaavi‐Kuopio kimberlites were emplaced when Rodinia break‐up was completed, coeval with formation of the Central Iapetus large igneous province. Magmas forming the Kaavi‐Kupio kimberlites may have formed from an upwelling mantle source similar to PREMA modified by increasing incorporation (up to 10%) of recycled crustal material through time accounting for the trend toward lower εHf(i) in these kimberlites.

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Section: Discussionmentioning

confidence: 99%

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Dalton

Giuliani

Hergt

et al. 2022

Geochem Geophys Geosyst

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“…During the Phanerozoic, our model suggests that TP decreased more gradually to reach the current average of ~1350 °C. This likely reflects a reduced subduction rate due to the assembly of the supercontinent Pannotia/Gondwana 45,46 at the end of the Neoproterozoic, as tracked by widespread Pan-African orogenesis 47,48 . Assembly of Pannotia/Gondwana would have provided thermal insulation below the amalgamated supercontinent, further slowing mantle cooling.…”

Section: Discussionmentioning

confidence: 99%

Continental basalts track secular cooling of the mantle and the onset of modern plate tectonics

Chen

Johnson

et al. 2021

Preprint

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The temperature of the convecting mantle exerts a first-order control on the tectonic behaviour of Earth’s lithosphere. Although the mantle has likely been cooling since the Archaean eon (4.0–2.5 billion years ago), how mantle temperature evolved thereafter is poorly understood. Here, we apply a statistical analysis to secular changes in the alkali index (A.I. = whole-rock (Na2O + K2O)2/(SiO2 – 38) as weight%) of intracontinental basalts globally to constrain the evolution of mantle potential temperature (Tp) over the past billion years. During the early Neoproterozoic, Tp remained relatively constant at ~1450 °C until the Cryogenian (720 to 635 million years ago), when mantle temperature dropped by ~50 °C over <180 million years. This remarkable episode of cooling records the onset of modern-style plate tectonics, which has been suggested to have been triggered by a dramatic increase in the supply of sediments to lubricate trenches during the thawing of the Snowball Earth.

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“…1 Ga, supercontinent. The debate on the existence of Pannotia has just been revived recently for example by Nance and Murphy (2018) or Kroner et al (2020) and in particular Murphy et al (2020). Keeping this issue in mind, however, the present study uses the widely accepted term Rodinia, but reserves the possibility to change the name when reconstructions back to 1 Ga or more will be made.…”

Section: Rodinia or Pannotia? Preliminary Remarksmentioning

confidence: 98%

888–444 Ma Global Plate Tectonic Reconstruction With Emphasis on the Formation of Gondwana

Vérard

2021

Front. Earth Sci.

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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.

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Pannotia: in defence of its existence and geodynamic significance

Cited by 39 publications

References 205 publications

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Continental basalts track secular cooling of the mantle and the onset of modern plate tectonics

888–444 Ma Global Plate Tectonic Reconstruction With Emphasis on the Formation of Gondwana

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