Biostratigraphic correlation of the western and eastern margins of the Labrador–Baffin Seaway and implications for the regional geology

Abstract

New analyses of the palynological assemblages in 13 offshore wells on the Canadian margin and six on the West Greenland Margin, in conjunction with onshore data, have led to a new biostratigraphic framework for the Cretaceous–Cenozoic strata of the Labrador Sea – Davis Strait – Baffin Bay (Labrador–Baffin Seaway) region and the first broad biostratigraphic correlation of the Canadian and Greenland margins. This framework is based on 167 last occurrences and 18 local/regional peak/common-occurrence events for dinocysts, miospores, fungal spores and Azolla. Detailed biostratigraphic evidence has confirmed the following hiatuses: pre-Aptian in the Hopedale Basin; pre-Albian in the Saglek Basin; Albian–Turonian in some wells of the Hopedale Basin; Turonian–Santonian/Campanian in some areas; pre-Campanian and late Campanian – Thanetian on the Greenland Margin; late Maastrichtian and Danian in some wells of the Hopedale Basin and in the Saglek Basin; Selandian in part of the Hopedale Basin, in all the Saglek Basin wells and in two wells on the West Greenland Margin; late Ypresian and/or Lutetian on both sides; Oligocene to middle Miocene of considerable variability on both margins, with all of the Oligocene and the lower Miocene missing in all the West Greenland Margin wells; and middle to late Miocene on the western side. On the Canadian margin, the hiatuses can be partially matched with the five previously recognised regional unconformities; on the Greenland margin, however, the relationship to the five unconformities is more tenuous. Palynomorph assemblages show that most Aptian to Albian sediments were deposited in generally non-marine to marginal marine settings, interrupted by a short-lived shallow marine episode in the Aptian. A marine transgression started in the Cenomanian–Turonian and led to the most open-marine, oceanic conditions in the Campanian–Lutetian; shallowing probably started in the late Lutetian and continued into the Rupelian, when inner neritic and marginal marine palaeoenvironments predominated. Throughout the rest of the Cenozoic, inner neritic palaeoenvironments alternated with marginal marine conditions on the margins of the Labrador–Baffin Seaway. These observations broadly reflect the tectonic evolution of the seaway, with rift conditions prevailing from Aptian to Danian times, followed by drift through much of the Paleocene and Eocene, and post-drift from Oligocene to the present. Dinocysts indicate that climatic conditions in the Labrador–Baffin Seaway region were relatively temperate in the Cretaceous, but varied dramatically through the Cenozoic. The Danian was a time of increasingly warmer climate, a thermal maximum being reached around the Paleocene–Eocene boundary reflecting the global thermal event at this time. Warm to hot conditions prevailed throughout the Ypresian, but the climate began to cool in the Lutetian, a trend that accelerated through the Priabonian and Rupelian. Throughout the Neogene, temperatures generally declined, culminating in the Quaternary.

A Cretaceous dinoflagellate cyst zonation for NE Greenland

“…However, an FO in the middle Turonian Stage and a first common occurrence in the uppermost Turonian Stage was reported by Pearce et al (2003). The FO of R. fucatum in the middle Turonian Stage is described by Costa & Davey (1992) and was also recorded from the North Sea area, Norwegian Sea and West Greenland by Radmacher et al (2015), Pedersen & Nøhr-Hansen (2014) and Nøhr-Hansen et al (2016), respectively; an upper Coniacian FO was reported by Nøhr-Hansen (2012) from the Sorgenfri Formation at Kangerlussuaq, southern East Greenland.…”

Depleted and ultradepleted basalt and picrite in the Davis Strait: Paleocene volcanism associated with a transform continental margin

“…1) bottomed in a local phonolitic volcano of Turonian age (c. 93 Ma, Knudsen et al 2019), and four wells -Hellefisk-1, Nukik-2, Gjoa G-37 and Hekja O-71 ( Fig. 1)drilled into thick successions of igneous rocks interlayered with and overlain by Paleocene sediments (Hald & Larsen, 1987;Nøhr-Hansen, 2003;Nøhr-Hansen et al 2016). North of 70°N the wells Alpha-1/S1 and Delta-1 bottomed in volcanic rocks overlain by Eocene sediments; the Delta-1 volcanic rocks are dated as of early Eocene age (Nelson et al 2015) and the Alpha-1/S1 rocks are presumed to be latest Paleocene in age (LM Larsen, unpub.…”

“…A few metres of sediments overlying the massive volcanic succession at 2548-2553 m are assigned to the ?Danian-Selandian stage, dinocyst palynozones P2/P3a? (Nøhr-Hansen et al 2016). These sediments are overlain by c. 150 m sediments of Selandian age, dinocyst palynozone P4, which gives an age interval of 60.7-59.2 Ma for the two interbedded hyaloclastite intervals.…”

Structural Evolution of the Rifted Margin off Northern Labrador: The Role of Hyperextension and Magmatism

“…Some of these wells reached Precambrian basement (Wasteneys et al, 1996). The oldest sediments are Early Cretaceous syn-rift sediments of the Bjarni Formation, found in only one well close to the basin's western margin, while the remainder of the wells sample Late Cretaceous and younger sediments (Nøhr-Hansen et al, 2016). However, more distal parts of the Saglek Basin have not been well-defined in terms of crustal or sedimentary characteristics (Balkwill & McMillan, 1990;Hinz et al, 1979;van der Linden, 1975).…”