New Insights into the Tectonostratigraphic Evolution of the Labrador Margin
Authors: Dickie Kate , Keen Charlotte , Williams Graham , Dehler Sonya A. 
Published: July 2010

To support the renewed interest in the hydrocarbon potential of the Labrador Sea, we have completed a regional seismic interpretation and integrated this with new biostratigraphic data, based on analyses of palynomorphs from wells in the Hopedale and Saglek basins. By integrating the two data-sets, we have developed a modified model for the evolution of the Labrador Margin. Our results are summarized in a tectonostratigraphic chart, which displays new and consistent age control for the major lithostratigraphic units and relates their depositional history to tectonic forces and global sea-level. Although we have identified and dated six regional unconformities in the wells, we can recognize several others on the seismic data. The older unconformities are related to the tectonics of rifting and seafloor spreading, and may delineate the onset of different stages of the rift process. In the Paleocene-Early Eocene, another significant influence was the episodic volcanism due to the passage of the proto-Iceland hot spot to the north, and to a major change in spreading direction in the Labrador Sea. During the post-seafloor spreading stage the effects of mass wasting and slumping, and of paleoenvironmental controls on the stratigraphy were more pronounced. We discuss the petroleum potential of the Hopedale Basin in terms of the structures we see on the seismic data, and highlight the Bjarni Formation, which appears to contain the most likely source and reservoir rocks.

Introduction

In September of 2008, oil companies bid a total of $186 million CAD for exploration rights on four parcels of land in the central Hopedale Basin (figures 1 and 2a). This is indicative of the renewed interest in the hydrocarbon potential of the region, which has been a focus of seismic exploration in the last five years (over 38,000 km of data was acquired by GSI and TGS). An earlier phase of exploration, from the late 1960's to the early 1980's, resulted in, a) acquisition of about 120,000 kilometers of seismic, b) drilling of 24 wells on the Labrador Margin and 3 more offshore SE Baffin Island, and c) five significant discoveries in the Hopedale Basin. Recoverable reserves total 4.2 tcf gas and 123 Mbbs of condensate (Government of Newfoundland and Labrador, 2000).

During the earlier phase of exploration, regional geological and geophysical studies of the Labrador Margin were published by Srivastava (1978), Umpleby (1979), McWhae (1981), Balkwill (1987), J.S. Bell (1989), Moir (1989) and Balkwill and McMillan (1990). Renewed interest has prompted a re-evaluation of the seismic data collected on the margin (Enachescu, 2006a,b; Dickie et al., 2009) and a re-appraisal of the biostratigraphy and paleoenvironments of the well sections (Williams, 2007a-d; Dickie et al., 2009). Tying together the seismic and palynologic data permits more precise age control on key seismic markers and delineation of the regional unconformities. Other significant advances elucidating the deep structure of the Labrador continental margins (Keen et al., 1994; Chian et al., 1995a,b; Funck et al., 2007; Gerlings et al., 2009) have proven to be pivotal in documenting the complex structure and evolution of non-volcanic margins globally (Peron-Pinvidic and Manatschal, 2008; Manatschal and Muntener, 2009), and has led to an improved understanding of the tectonic history of the Labrador Margin. Major paleooceanographic events affecting the Labrador Sea have become well documented through deep drilling in the Arctic (Moran et al., 2006) and IODP drilling elsewhere.