Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs
A compilation of 178 more precise ages on 10 potential Large Igneous Provinces (LIPs) across southern Africa, is compared to Earth’s supercontinental cycles, where 5 more prominent LIP-events all formed during the assembly of supercontinents, rather than during breakup. This temporal bias is confirm...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2020-09-01
|
| Series: | Geoscience Frontiers |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987119302397 |
| _version_ | 1797701720596283392 |
|---|---|
| author | Martin B. Klausen |
| author_facet | Martin B. Klausen |
| author_sort | Martin B. Klausen |
| collection | DOAJ |
| description | A compilation of 178 more precise ages on 10 potential Large Igneous Provinces (LIPs) across southern Africa, is compared to Earth’s supercontinental cycles, where 5 more prominent LIP-events all formed during the assembly of supercontinents, rather than during breakup. This temporal bias is confirmed by a focused review of field relationships, where these syn-assembly LIPs formed behind active continental arcs; whereas, the remaining post-assembly – and likely breakup-related – LIPs never share such associations. Exploring the possibility of two radically different LIP-types, only the two younger breakup events (the Karoo LIP and Gannakouriep Suite) produced basalts with more enriched asthenospheric OIB-signatures; whereas, all assembly LIPs produced basalts with stronger lithospheric, as well as more or less primitive asthenospheric, signatures. A counterintuitive observation of Precambrian breakup LIPs outcropping as smaller fragments that are more peripherally located along craton margins, compared to assembly LIPs as well as the Phanerozoic Karoo breakup LIP, is explained by different preservation potentials during subsequent supercontinental cycles. Thus, further accentuating radical differences between (1) breakup LIPs, preferentially intruding along what evolves to become volcanic rifted margins that are more susceptible to deformation within subsequent orogens, and (2) assembly LIPs, typically emplaced along back-arc rifts within more protected cratonic interiors. A conditioned duality is proposed, where assembly LIPs are primarily sustained by thermal blanketing (as well as local arc hydration and rifting) below assembling supercontinents and breakup LIPs more typically form above impinging mantle plumes. Such a duality is further related to an overall dynamic Earth model whereby predominantly supercontinent-orientated ocean lithospheric subduction establishes/revitalizes large low shear velocity provinces (LLSVPs) during assembly LIP-activity, and heating of such LLSVPs by the Earth’s core subsequently leads to a derivation of mantle plumes during supercontinental breakup. |
| first_indexed | 2024-03-12T04:40:46Z |
| format | Article |
| id | doaj.art-2cf40423493944aba4060c1bbe189f0a |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T04:40:46Z |
| publishDate | 2020-09-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-2cf40423493944aba4060c1bbe189f0a2023-09-03T09:41:55ZengElsevierGeoscience Frontiers1674-98712020-09-0111516351649Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPsMartin B. Klausen0Department of Earth Sciences, Stellenbosch University, Private Bag X1, Matieland, South AfricaA compilation of 178 more precise ages on 10 potential Large Igneous Provinces (LIPs) across southern Africa, is compared to Earth’s supercontinental cycles, where 5 more prominent LIP-events all formed during the assembly of supercontinents, rather than during breakup. This temporal bias is confirmed by a focused review of field relationships, where these syn-assembly LIPs formed behind active continental arcs; whereas, the remaining post-assembly – and likely breakup-related – LIPs never share such associations. Exploring the possibility of two radically different LIP-types, only the two younger breakup events (the Karoo LIP and Gannakouriep Suite) produced basalts with more enriched asthenospheric OIB-signatures; whereas, all assembly LIPs produced basalts with stronger lithospheric, as well as more or less primitive asthenospheric, signatures. A counterintuitive observation of Precambrian breakup LIPs outcropping as smaller fragments that are more peripherally located along craton margins, compared to assembly LIPs as well as the Phanerozoic Karoo breakup LIP, is explained by different preservation potentials during subsequent supercontinental cycles. Thus, further accentuating radical differences between (1) breakup LIPs, preferentially intruding along what evolves to become volcanic rifted margins that are more susceptible to deformation within subsequent orogens, and (2) assembly LIPs, typically emplaced along back-arc rifts within more protected cratonic interiors. A conditioned duality is proposed, where assembly LIPs are primarily sustained by thermal blanketing (as well as local arc hydration and rifting) below assembling supercontinents and breakup LIPs more typically form above impinging mantle plumes. Such a duality is further related to an overall dynamic Earth model whereby predominantly supercontinent-orientated ocean lithospheric subduction establishes/revitalizes large low shear velocity provinces (LLSVPs) during assembly LIP-activity, and heating of such LLSVPs by the Earth’s core subsequently leads to a derivation of mantle plumes during supercontinental breakup.http://www.sciencedirect.com/science/article/pii/S1674987119302397Large igneous provincesExtrovert plate tectonicsLLSVPMantle dynamicsGeochemical discrimination |
| spellingShingle | Martin B. Klausen Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs Geoscience Frontiers Large igneous provinces Extrovert plate tectonics LLSVP Mantle dynamics Geochemical discrimination |
| title | Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs |
| title_full | Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs |
| title_fullStr | Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs |
| title_full_unstemmed | Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs |
| title_short | Conditioned duality between supercontinental ‘assembly’ and ‘breakup’ LIPs |
| title_sort | conditioned duality between supercontinental assembly and breakup lips |
| topic | Large igneous provinces Extrovert plate tectonics LLSVP Mantle dynamics Geochemical discrimination |
| url | http://www.sciencedirect.com/science/article/pii/S1674987119302397 |
| work_keys_str_mv | AT martinbklausen conditioneddualitybetweensupercontinentalassemblyandbreakuplips |