Detrital monazite geochronology, Upper Jurassic–Lower Cretaceous of the Scotian Basin: significance for tracking first-cycle sources

Abstract

Monazite geochronology was applied to an east-west transect of latest Jurassic and Lower Cretaceous deltaic sandstones of the Scotian Basin, to assess sediment sources and dispersal pathways. More than 200 detrital monazite grains yielded 694 electron microprobe age determinations with 1s errors ,+20%. Based on age, external morphology, zoning, inclusions and major element chemistry (rare earth element [REE], Th, Y), monazite grains represent more than 20 discrete sources. Similar proportions of euhedral and subhedral compared with irregular and rounded monazite grains in most age classes, together with comparison with detrital muscovite and zircon geochronology, suggest that most monazite is first cycle. Six types of REE distribution are recognized (A-F). Many igneous monazites show chemical zoning, contain sparse euhedral inclusions, and have REE distributions of types A and E. Many metamorphic monazites contain inclusions, commonly aligned, are generally rounded-subhedral to rounded, and have REE distributions of types B, C and D. Monazite geochronology shows important supply to the Scotian Basin from the Labrador rift shoulder as early as Tithonian; from Avalonian sources in the Tithonian; from Ordovician sources in northern New Brunswick, apparently via the Chaswood River; and from the inner continental shelf, particularly in the Hauterivian -Barremian.

Forward stratigraphic modelling of sediment pathways and depocentres in salt‐influenced passive‐margin basins: Lower Cretaceous, central Scotian Basin

“…Sand‐rich sedimentation returned during the Albian; during this time, the uplift of the Meguma Terrane had slowed (Reynolds et al, ) and the Sable and Banquereau rivers eroded through the Aptian basalt flows (Bowman et al, ). These sand‐rich sediments comprise the Cree Member of the Logan Canyon Formation, and share similar composition and geochemistry with the Upper Missisauga Formation (Pe‐Piper et al, ; Piper et al, ; Reynolds et al, ; Zhang et al, ), suggesting a return to the pre‐Naskapi member sedimentation conditions.…”

“…The Sable River was a large drainage system which sourced sediments from a variety of terrains to the central Scotian Basin, including the Mesoproterozoic Grenville Province of southern Labrador and eastern Quebec, the late Paleoproterozoic Makkovik Province of central Labrador, the Long Range inlier of western Newfoundland, Palaeozoic crystalline basement of the Appalachian orogen, and polycyclic sediments from the Carboniferous Maritimes Basin (Pe‐Piper & Piper, ; Piper, Pe‐Piper, Tubrett, Triantafyllidis, & Strathdee, ; Tsikouras, Pe‐Piper, Piper, & Schaffer, ). The Banquereau River supplied sediment dominantly to the eastern basin and was sourced through the Humber Valley in western Newfoundland from terrains found in central Newfoundland (Tsikouras et al, ) with minor sediments sourced from the Grenville and Makkovik provinces in the Labrador Rift (Pe‐Piper, Piper, & Triantafyllidis, ).…”

“…As a result, the three river systems supplying the Scotian Basin were active at different times during the Early Cretaceous. The Middle and Upper Mississauga formations in the Central Scotian Basin received sediments from the Sable River, the Banquereau River, and from small rivers draining the Meguma Terrain (Pe‐Piper et al, ; Piper et al, ; Reynolds et al, ; Tsikouras et al, ; Zhang et al, ). However, there was a shift in sedimentation style during the Aptian, when the Naskapi Member was deposited.…”

“…Based on the published provenance studies (Pe‐Piper et al, ; Piper et al, ; Reynolds et al, ; Tsikouras et al, ; Zhang et al, ), three sources are used to simulate the Upper Missisauga Formation and Cree Members: a large central source to reproduce the Sable River, an Eastern source to reproduce the Banquereau River, and a Western source to reproduce input from the Meguma Terrane (Figure a). During the Aptian blockage of the Sable and Banquereau rivers (Chavez et al, ), a single source is used to simulate the Naskapi Member (Figure b).…”

Sediment provenance studies in hydrocarbon exploration and production: an introduction

“…In a break from the conventional U -Pb dating of zircon, Pe-Piper et al (2013) explore the use of monazite geochronology as a sediment provenance tool. The study combines the monazite geochronological data with morphology, zoning, inclusions and major element geochemistry data to identify 20 discrete sedimentary sources.…”