40 Ar- 39 Ar ages of lavas from the southeast Greenland Margin, ODP Leg 152, and the Rockall Plateau, DSDP Leg 81

Abstract

ABSTRACT40 Ar incremental heating experiments were performed on volcanic rocks recovered by drilling during Ocean Drilling Program Leg 152, southeast Greenland Margin (63°N), and Deep Sea Drilling Project Leg 81, southwest Rockall Plateau (56°N). Both of these legs drilled into thick sections of submerged lava flows, known as seaward-dipping reflector sequences, that are part of the Tertiary North Atlantic Volcanic Province (NAVP). Results show that subaerial volcanism began at the southeast Greenland Margin as early as 61−62 Ma with the eruption of continentally contaminated lavas. After an apparent hiatus, volcanism continued with the subaerial eruption of noncontaminated, mid-ocean-ridge basalt (MORB) -like lavas. A sill or flow was emplaced at 52 Ma into the sediments overlying the basement lavas at the most seaward site (918). The MORB-like lavas of the Rockall Plateau gave poor results, although the data suggest that they erupted at 57−58 Ma and may be contemporaneous with the compositionally similar oceanic lavas of Leg 152.Compiled ages from the NAVP indicate that most of the lavas were erupted in two distinct magmatic episodes. The first occurred prior to 60 Ma with volcanism at the southeast Greenland Margin, in West Greenland, and the northwest British Isles. This early stage of widespread volcanism most likely records the arrival of the Iceland mantle plume. The second phase of magmatism began about 57 Ma with voluminous basaltic eruptions centralized along the eventual line of continental separation. Magmatism at this stage was associated with continental breakup and asthenospheric upwelling with probable thermal input from the mantle plume.

Latest Danian carbon isotope anomaly and associated environmental change in the southern Tethys (Nile Basin, Egypt)

“…This suggests a duration of <100 ka for the LDE, in contrast to the cyclostratigraphic results from Zumaia. The C27n-C26r transition is further characterized by a significant increase in oceanic spreading rates (Westerhold et al 2008) and enhanced volcanic activity at the SE Greenland margin (Sinton & Duncan 1998), which might be related to the palaeoenvironmental changes reported for the latest Danian by Speijer (2003) and herein.…”

A high-resolution benthic stable-isotope record for the South Atlantic: Implications for orbital-scale changes in Late Paleocene–Early Eocene climate and carbon cycling

“…Superimposed on these long-term climate and carbon-cycle trends were a series of high-amplitude, transient perturbations to the climate and carbon-cycle known as "hyperthermals", the largest and best-studied of which is the Paleocene Eocene Thermal Maximum (PETM; ETM-1; ∼55.5 Ma) (e.g., Kennett and Stott, 1991;Zachos et al, 2005;Lourens et al, 2005;Röhl et al, 2007;Tripati and Elderfield, 2005;Sluijs et al, 2006Sluijs et al, , 2007Nicolo et al, 2007;McInerney and Wing, 2011). At least three such hyperthermals are recognized in the Early Eocene (ETM-1 to 3), which all share similar characteristics of rapid and large increases in global temperature accompanied by transient changes to the global carbon-cycle, as recorded by negative excursions in δ 18 O and δ 13 C records, and evidence for massive dissolution of deep-sea marine carbonates (e.g., Zachos et al, 2005;Lourens et al, 2005;Sluijs et al, 2009;Agnini et al, 2009;Stap et al, 2009Stap et al, , 2010aStap et al, , 2010bMcInerney and Wing, 2011;Komar et al, 2013).…”

Post-breakup basaltic magmatism along the East Greenland Tertiary rifted margin

“…[1]. Briefly, magmatism began with the eruption of the Lower Lava Series from ODP Leg 152 at 63ºN, Site 917 (63-61 Ma [51]), and with the Lower Lava Series and related dykes (>56 Ma [9,52]) in the Patulajivit-Lilloise sector. The major expression of flood basalt magmatism that formed the Blosseville-Scoresby Sund plateau basalts (Middle Series) at 56-55 Ma; [8][9][10], was contemporaneous with the formation of seaward-dipping reflector sequences, such as the Upper Series of ODP 63ºN transect, Site 917 [53], the basalts of the Vøring Plateau [54] and was roughly coeval with the establishment of the oceanic spreading ridge offshore [11].…”