A Mid-Mesozoic Breccia from the Coast of Labrador

Abstract

A unique occurrence of Mesozoic breccia cut by lamprophyric-carbonatite dikelets, near Makkovik, Labrador is interpreted to relate to the opening of the Labrador Sea. The breccia has been dated by nannofossils; vitrinite reflectance studies show that some time during or after deposition the rock was heated to at least 170 °C. It is suggested that shallow seas extended westward beyond the present Labrador Marginal Trough during early Jurassic time and that the period of late alkaline igneous activity is related to the rifting between Greenland and Labrador that commenced about the middle of the Mesozoic Era.

Evidence for an Albian Hudson arm connection between the Cretaceous Western Interior Seaway of North America and the Labrador Sea

“…We suggest that the combination of faunal ties between the Cretaceous Western Interior Seaway and the proto-North Atlantic and the lack of an Albian-Turonian physical connection between the Labrador Sea and the Arctic Ocean provide an intriguing argument for implicating a connection between the Atlantic Ocean and the Cretaceous Western Interior Figure 1. Geologic map of Cretaceous strata in most of eastern North America (from Balkwill et al, 1983;Blais, 1959;Burden and Langille, 1991;Burden and Holloway, 1985;Cook and Bally, 1972;Escher and Pulvertaft, 1995;Fuller, 1961;Gohn, 1988;Grant and McAlpine, 1990;Henderson et al, 1976;King and McMillan, 1975;Ludvigson and Witzke, 1996;McFarlan and Menes, 1991;Miall et al, 1980;Norris, 1993;Norris and Zippi, 1991;Remick et al, 1963;Sanford and Grant, 1990;Sohl et al, 1991;Tschudy, 1965;Umpleby, 1979;Wade and MacLean, 1990;Williams, 1948;Ziegler and Rowley, 1998;and Zippi and Bajc, 1990), including hypothesized hotspot tracks associated with the New England and Newfoundland Seamounts (Duncan, 1984). Note that black dots designate small outliers from the mid-Cretaceous outcrop belt.…”

An evaluation of Mesozoic rift-related magmatism on the margins of the Labrador Sea: Implications for rifting and passive margin asymmetry

“…Our AP2 sample location in Ford's Bight is in very close proximity to the diatreme originally described as a sedimentary breccia by King and McMillan (1975) and later as a diatreme by Wilton et al (2002). Our field observations concur with that of Wilton et al (2002) that the AP2 sample location is part of the previously documented Ford's Bight diatreme.…”

“…4. The most reliable evidence for Mesozoic magmatism around Makkovik is the diatreme in Ford's Bight dated using fossil evidence by King and McMillan (1975). The diatreme was not observed to be part of a dike swarm as implied by the sample locations in Tappe et al (2007).…”

Early Tertiary basalts from the Labrador Sea floor and Davis Strait region

“…The igneous history of this region, as in other rift systems (Rosendahl 1987), is complex and subdivides into three geographical -temporal groups becoming progressively younger toward the axis of the Labrador Sea. The first of these consists of volumetrically small, highly alkaline lamprophyres, kimberlites , and carbonatites of Jurassic -Cretaceous age cutting the Precambrian basement of both coastal Labrador and southwest Greenland (Leech et al 1963;Larsen and Moller 1968;Emeleus and Andrews 1975;King and McMillan 1975;Clarke 1977;Hansen 1980). The second occurs as mafic volcanic units of Jurassic-Cretaceous age recovered in well cuttings from the continental shelves of both Labrador and southwest Greenland (Muecke et al, in preparation).…”