Seismic stratigraphy and late Quaternary sedimentary history of Bonavista Bay, northeastern Newfoundland

• Main Author: Cumming, Ewan Hugh
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1990
• Subjects: Chandler; Inner Bay; Bonavista Bay; Ice Sheet; Newfoundland
• Online Access: https://research.library.mun.ca/6702/; https://research.library.mun.ca/6702/1/EwanHughCumming.pdf; https://research.library.mun.ca/6702/3/EwanHughCumming.pdf

The Late Quaternary glacial and sedimentary history of Bonavista Bay, on the NE coast of Newfoundland, is interpreted from 545 line km of high-resolution seismic reflection data and three piston cores. Seismic data from the open, outer region of Bonavista Bay display three seismic units (1-3) overlying acoustic basement within two broad, shallow basins. The surveyed inner region of Bonavista Bay contains narrow, deep basins which commonly host four seismic units (A-D) above acoustic basement. -- Glacial sediments are represented by seismic units 1 and A, both of which are acoustically incoherent. Unit 1 is generally <15 ms thick and has a variable morphology. It is correlated with a stiff, sandy, gravelly mud (diamicton). Unit A is up to 110 ms thick and ponded. Units 2, B and C are proglacial sequences. Unit 2 is acoustically stratified, <20 ms thick and has a draping basin-fill morphology. It is correlated with an interlaminated sequence of distal turbidites and hemipelagic/ice-rafted sediment. Unit B is acoustically transparent, ponded and up to 30 ms thick. It corresponds with a proglacial homogeneous silty mud, rapidly deposited under open water conditions until 12,790 y BP (in Chandler Reach). Unit C, overlying B, is acoustically stratified, up to 90 ms thick and has a draping basin-fill morphology. It is correlated with a sandy, pebbly and shelly mud, deposited by hemipelagic, terrestrial and ice-rafted sedimentation from 12,790 y BP to 10,170 y BP. Seismic units 3 and D are acoustically transparent post-glacial sequences with an average thickness of 20 ms. They display a draping basin-fill morphology which has been altered by erosion and are correlated with a sandy, pebbly and shelly hemipelagic mud; initially deposited in the outer bay by 13,500 y BP and in the inner bay by 10,170 y BP (Chandler Reach). -- Bonavista Bay was host to a grounded Late Wisconsinan ice sheet. Deglaciation of the bay was rapid and occurred at a time of rising sea level. Initially a thin basal till was deposited beneath ...