Proterozoic massif-type anorthosites as the archetypes of long-lived (≥100 Myr) magmatic systems—New evidence from the Kunene Anorthosite Complex (Angola)

Bybee, G. M.; Hayes, Ben; Owen-Smith, T.; Lehmann, J.; Ashwal, Lewis D.; Brower, A. M.; Hill, Catherine Mary; Corfú, Fernando; Manga, M.

doi:10.1016/j.precamres.2019.105393

Cited by 28 publications

(20 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, samples that are somehow connected with the Epupa (e.g. Kröner et al 2015;Seth et al 2003; and Kunene Anorthosite complexes (Baxe 2007;Bybee et al 2019;Lehmann et al 2020) can easily be distinguished from almost all other samples reported from the Congo and Kalahari Cratons (Fig. 5; Fig.…”

Section: Detrital Zircon Age Patterns and Hf-isotopesmentioning

confidence: 90%

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Gärtner

Hofmann

Zieger

et al. 2021

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

Extensive morphological and age studies on more than 4600 detrital zircon grains recovered from modern sands of Namibia reveal complex mechanisms of sediment transport. These data are further supplemented by a zircon age database containing more than 100,000 single grain analyses from the entire southern Africa and allow for hypothesising of a large Southern Namibian Sediment Vortex located between the Damara Orogen and the Orange River in southern Namibia. The results of this study also allow assuming a modified model of the Orange River sand highway, whose origin is likely located further south than previously expected. Moreover, studied samples from other parts of Namibia give first insights into sediment movements towards the interior of the continent and highlight the potential impact of very little spatial variations of erosion rates. Finally, this study points out the huge potential of detrital zircon morphology and large geo-databases as an easy-to-use additional tool for provenance analysis.

show abstract

Section: Detrital Zircon Age Patterns and Hf-isotopesmentioning

confidence: 90%

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Gärtner

Hofmann

Zieger

et al. 2021

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

show abstract

“…Their isotope compositions also suggest that crustal assimilation occurred before plagioclase accumulation . The accumulation of buoyant plagioclase enabled the ascent of the anorthositic crystal mushes through the crust leaving denser mafic cumulates behind (e.g., Bybee et al 2019). Some HAOMs were carried to shallower crustal levels by the ascending mushes and record mineralogical evidence of low-pressure re-equilibration (e.g., exsolved plagioclase lamellae; Emslie 1975).…”

Section: Implications For the Petrogenesis Of The Ahvenisto Complex Amentioning

confidence: 99%

Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

Fred

Heinonen

2020

Contrib Mineral Petrol

View full text Add to dashboard Cite

Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well.

show abstract

“…Traditionally, massif-type anorthosites and AMCG complexes have been regarded as 'anorogenic' in nature (e.g., Anderson, 1983;Ashwal, 1993;Emslie, 1991; amongst many others), which has posed complexities for interpreting the AMCG magmatism within Oaxaquia (see discussion in Weber et al, 2010). Nevertheless, recent advances in our understanding of AMCG associations and their relationship with regional tectonic regimes using modern geochronologic methods, are shifting this long-standing view in favor a convergent (i.e., Andean-type) margin for their origin (e.g., Ashwal & Bybee, 2017;Bybee et al, 2019). Indeed, voluminous AMCG magmatism at 1.08-1.03 in the Grenville Orogen post-dates arc accretion (Shawinigan event) and predates collisional orogenesis (Ottawan event), and evidently took place within a convergent margin (e.g., Bickford et al, 2010;Hamilton et al, 2004;Mc-Lelland et al, 2004.…”

Section: Anorthosite-mangerite-charnockite-granite (Amcg) Magmatism (Ca 102 To 100 Ga)mentioning

confidence: 99%

Volume 1

SGC¹

2019

View full text Add to dashboard Cite

show abstract

Proterozoic massif-type anorthosites as the archetypes of long-lived (≥100 Myr) magmatic systems—New evidence from the Kunene Anorthosite Complex (Angola)

Cited by 28 publications

References 74 publications

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

Volume 1

Contact Info

Product

Resources

About

Proterozoic massif-type anorthosites as the archetypes of long-lived (≥100 Myr) magmatic systems—New evidence from the Kunene Anorthosite Complex (Angola)

Cited by 28 publications

References 74 publications

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Implications for sedimentary transport processes in southwestern Africa: a combined zircon morphology and age study including extensive geochronology databases

Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

Volume 1

Contact Info

Product

Resources

About

Proterozoic massif-type anorthosites as the archetypes of long-lived (≥100 Myr) magmatic systems—New evidence from the Kunene Anorthosite Complex (Angola)