Over one billion years of Archean crust evolution revealed by zircon U-Pb and Hf isotopes from the Saglek-Hebron complex

Wasilewski, Benjamin; O’Neil, Jonathan; Rizo, Hanika; Paquette, Jean‐Louis; Gannoun, Abdelmouhcine

doi:10.1016/j.precamres.2021.106092

Cited by 17 publications

(7 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although a definitive history of the duration of the Neoarchean metamorphic event (s ?) in the Saglek Block is still pending, numerous studies have reported late Neoarchean U-Pb ages measured in accessory phases, such as zircon, titanite and apatite [5,28,30,[38][39][40]43,46,47,68]. Based on these studies, and the results presented here, two thermal events seem to have occurred during the Neoarchean/early-Paleoproterozoic: one at ca.…”

Section: The Neoarchean Metamorphic History Of the Saglek Blocksupporting

confidence: 64%

“…2.5-2.4 Ga, referred to as M1, M2 and, M3, respectively, in the following. In addition to field and petrographic evidence, these three metamorphic events have been identified via isotopic measurements at the whole-rock scale [31,[34][35][36][37] and further confirmed by U-Th-Pb isotope analyses of accessory minerals [38][39][40][41][42][43][44][45], sometimes combined with Hf-isotopes [28,46], Hf-and O-isotopes [5,47], and Sm-Nd isotopes [28,30].…”

Section: The Saglek Block An Archean Poly-metamorphic Terranementioning

confidence: 90%

“…In-situ investigations of Hf isotopic compositions in the Saglek Block have clearly identified the redistribution of Hf isotopes [5,46,47] via: (i) dissolution-reprecipitation of zircon during a ca. 3.6 Ga metamorphic event, with newly formed zircon crystals/domains inheriting Hf from the older, dissolved zircon domains; and (ii) dissolution-reprecipitation of zircon during a ca.…”

Section: Diachronous Redistribution Of Hf and Nd Isotopes In The Saglek Blockmentioning

confidence: 99%

“…In summary, the two Neoarchean/early-Paleoproterozoic metamorphic events of the Saglek Block seem to involve the reworking of local crustal lithologies, both igneous and sedimentary, with the subtle but unequivocal indications of exotic fluids carrying Hf and Nd with isotopic compositions more radiogenic than the regional crustal signature. Based on the presently available datasets [5,24,[38][39][40]46,47,68], the igneous and metamorphic history of the Saglek Block can be summarized as followed:…”

Section: The Neoarchean Metamorphic History Of the Saglek Blockmentioning

confidence: 99%

See 3 more Smart Citations

Diachronous Redistribution of Hf and Nd Isotopes at the Crystal Scale—Consequences for the Isotopic Evolution of a Poly-Metamorphic Crustal Terrane

et al. 2022

View full text Add to dashboard Cite

In metamorphic rocks, mineral species react over a range of pressure–temperature conditions that do not necessarily overlap. Mineral equilibration can occur at varied points along the metamorphic pressure–temperature (PT) path, and thus at different times. The sole or dominant use of zircon isotopic compositions to constrain the evolution of metamorphic rocks might then inadvertently skew geological interpretations towards one aspect or one moment of a rock’s history. Here, we present in-situ U–Pb/Sm–Nd isotope analyses of the apatite crystals extracted from two meta-igneous rocks exposed in the Saglek Block (North Atlantic craton, Canada), an Archean metamorphic terrane, with the aim of examining the various signatures and events that they record. The data are combined with published U–Pb/Hf/O isotope compositions of zircon extracted from the same hand-specimens. We found an offset of nearly ca. 1.5 Gyr between U-Pb ages derived from the oldest zircon cores and apatite U–Pb/Sm–Nd isotopic ages, and an offset of ca. 200 Ma between the youngest zircon metamorphic overgrowths and apatite. These differences in metamorphic ages recorded by zircon and apatite mean that the redistribution of Hf isotopes (largely hosted in zircon) and Nd isotopes (largely hosted in apatite within these rocks), were not synchronous at the hand-specimen scale (≤~0.001 m3). We propose that the diachronous redistribution of Hf and Nd isotopes and their parent isotopes was caused by the different PT conditions of growth equilibration between zircon and apatite during metamorphism. These findings document the latest metamorphic evolution of the Saglek Block, highlighting the role played by intra-crustal reworking during the late-Archean regional metamorphic event.

show abstract

Section: The Neoarchean Metamorphic History Of the Saglek Blocksupporting

confidence: 64%

Section: The Saglek Block An Archean Poly-metamorphic Terranementioning

confidence: 90%

Section: Diachronous Redistribution Of Hf and Nd Isotopes In The Saglek Blockmentioning

confidence: 99%

Section: The Neoarchean Metamorphic History Of the Saglek Blockmentioning

confidence: 99%

See 2 more Smart Citations

Diachronous Redistribution of Hf and Nd Isotopes at the Crystal Scale—Consequences for the Isotopic Evolution of a Poly-Metamorphic Crustal Terrane

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The most proximal sources of Neoarchean to Mesoarchean detrital zircon age fractions in our samples, which result in ca. 2800-2700 Ma age peaks, may be derived from metaigneous rocks in the Nain Province or North Atlantic craton of Labrador (e.g., Dunkley et al, 2020) that yield subchondritic to superchondritic Hf isotope compositions (e.g., Wasilewski et al, 2021) like those documented in Labrador and Curling group strata. The U-Pb ages and subchondritic to chondritic Hf isotope compositions of Paleo-to Eoarchean (ca.…”

Section: Sediment Provenancementioning

confidence: 99%

Late Ediacaran to Early Cambrian Breakup Sequences and Establishment of the Eastern Laurentian Passive Margin, Newfoundland, Canada

Soukup,

Beranek,

Lode

et al. 2024

American Journal of Science

View full text Add to dashboard Cite

Sediment provenance studies were conducted to constrain the establishment of the eastern Laurentian or Humber passive margin in Newfoundland, Canada, and examine models for the opening of the Iapetus Ocean and Humber Seaway. Ediacaran to Cambrian Series 2 strata of the lower Labrador and Curling groups contain garnet, muscovite, and feldspar, and yield 1000–1500 Ma detrital zircon grains that reflect local derivation from Grenville Province basement rocks during regional extensional deformation. Cambrian Series 2 to early Miaolingian units of the upper Labrador and Curling groups are quartz-rich and characterized by 556–586 Ma and 1000–2700 Ma detrital zircon grains that instead reflect continental-scale drainage and transition to passive margin deposition along eastern Laurentia. The geological relationships along the Humber margin are compared with modern analogues in the Newfoundland-west Iberia rift system to propose a magma-poor rift model that includes two breakup sequences which formed in response to isostatic adjustment after the rupture of crust and mantle, respectively. Crustal breakup resulted in an Ediacaran to Cambrian Series 2 breakup sequence that was connected to hyperextension, mantle exhumation, and bimodal magmatism. Mantle breakup likely occurred >20 Myr after first mantle exhumation and resulted in a breakup sequence that is best characterized by Cambrian Series 2 to early Miaolingian strata. The mantle breakup sequence consists of regressive-transgressive cycles that record the transition from breakup to thermal subsidence and was probably driven by the separation of the Dashwoods microcontinent from eastern Laurentia and outboard opening of west Iapetus. The Humber Seaway opened between the Humber margin and Dashwoods and was at least partially underlain by exhumed continental mantle. Our scenarios support hypotheses for equivalent magma-poor rift elements elsewhere in the Caledonian-Appalachian orogen, and we predict that crustal and mantle breakup sequences are exposed in the Scotland-Ireland and Quebec-New England segments of the eastern Laurentian margin.

show abstract

Saglek-Hebron Complex (Northern Labrador, Canada)

Rizo

O’Neil

2022

Encyclopedia of Astrobiology

View full text Add to dashboard Cite

Over one billion years of Archean crust evolution revealed by zircon U-Pb and Hf isotopes from the Saglek-Hebron complex

Cited by 17 publications

References 87 publications

Diachronous Redistribution of Hf and Nd Isotopes at the Crystal Scale—Consequences for the Isotopic Evolution of a Poly-Metamorphic Crustal Terrane

Diachronous Redistribution of Hf and Nd Isotopes at the Crystal Scale—Consequences for the Isotopic Evolution of a Poly-Metamorphic Crustal Terrane

Late Ediacaran to Early Cambrian Breakup Sequences and Establishment of the Eastern Laurentian Passive Margin, Newfoundland, Canada

Saglek-Hebron Complex (Northern Labrador, Canada)

Contact Info

Product

Resources

About