New age data refine extent and duration of Paleozoic and Neoproterozoic plutonism at Ganderia–Avalonia boundary, Newfoundland

Abstract

Devonian and younger plutonic suites of the Appalachian orogen in Newfoundland form a curvilinear belt straddling the boundary between Ganderia and Avalonia, and exhibit a general pattern of younging to the southeast. However, many individual plutonic suites within this belt remain undated or have ages that are poorly constrained. This study reports U-Pb sensitive highresolution ion microprobe (SHRIMP) data from zircon and 40 Ar-39 Ar data from hornblende, biotite, and muscovite, which collectively improve definition of post-tectonic plutonic events in southeastern Newfoundland, but at the same time raise new questions for further study. U-Pb zircon SHRIMP determinations provide valuable new geochronological information for the Deadman's Bay

The Lac au Renard Tephra Cluster: a record of Lochkovian (Lower Devonian) volcanism in the Indian Point Formation, Gaspe Peninsula, Quebec, Canada

“…We emphasize that this will not be an exhaustive review of Late Silurian to Early Devonian magmatism in the Appalachian-Caledonide system, but rather it provides context for our assertion that numerous regions experienced felsic magmatism during deposition of the Indian Point Formation and the included Lac au Renard Tephra Cluster. Kellett et al (2014) reported a SHRIMP date of 423 ± 4 Ma (Hon et al 1991) likely overlap in age with the Lac au Renard Tephra Cluster of Gaspe. Llamas and Hepburn (2013) reported that the Coastal Volcanic belt of Maine consists of Silurian-Devonian volcanic rocks related to the collision of Avalonia with Laurentia, just before and during the early stages of the Acadian orogeny.…”

Terrane history of the Iapetus Ocean as preserved in the northern Appalachians and western Caledonides

“…Negative ε Nd values, the presence of Cryogenian volcanic rocks, a distinct Cambrian succession, and the presence of a Silurian intrusion (Kellett et al, 2014) all suggest possible links to other Avalonian terranes.…”

“…9), which shows pervasive development of Acadian sinistral strike-slip fabrics. Those fabrics are overprinted by later dextral fabrics in a narrow zone along the boundary with sub-greenschist facies rocks of the Avalon terrane, marked by the Dover Fault (Holdsworth, 1994;Kellett et al, 2014Kellett et al, , 2016. Salinian-accreted terranes in central Newfoundland are deformed by NW-vergent Acadian thrusts and folds (Valverde-Vaquero et al, 2006a;van Staal et al, 2014), and Acadian deformation reactivated Taconian normal faults at the thrust front in western Newfoundland (Waldron et al, 1993;.…”

Seismic Evidence for Proterozoic Collisional Episodes along Two Geosutures within the Southern Granulite Province of India

“…It is thought that the Salinic orogeny produced older subduction-related plutons and younger postcollisional (back-arc) plutons via slab detachment after the cessation of subduction [40][41][42][43] Plutonism in the region continued from the Late Silurian to Early Devonian and may be related to either the early stages of the Acadian orogeny (420 Ma to 410 Ma) or postcollisional crustal relaxation. The plutons are found across the trailing (eastern) edge regions of the Gander terrane and the boundary region between the Gander and Avalon terranes [38,45,46,48,53,[59][60][61][62][63]. Subsequent to the Avalon-Laurentia collision (435 Ma to 430 Ma), the Meguma terrane was thrust over Avalonia (~400 Ma) and both terranes were intruded by middle to late Devonian mafic and silicic plutonic rocks [33,45,60,[64][65][66][67].…”

“…The plutons are found across the trailing (eastern) edge regions of the Gander terrane and the boundary region between the Gander and Avalon terranes [38,45,46,48,53,[59][60][61][62][63]. Subsequent to the Avalon-Laurentia collision (435 Ma to 430 Ma), the Meguma terrane was thrust over Avalonia (~400 Ma) and both terranes were intruded by middle to late Devonian mafic and silicic plutonic rocks [33,45,60,[64][65][66][67]. Consequently, the precise terrane correlation of the Blair River inlier rocks is difficult to discern based on just their ages as they are more likely to be related to either the Avalon terrane or the Gander terrane than Laurentia.…”