Late Quaternary Glaciation and Postglacial Stratigraphy of the Northern Pacific Margin of Canada

Abstract

Areas of southeastern Alaska and the Queen Charlotte Islands of the northwestern Pacific coast of North America were considered to be ice free during the late Wisconsinan glaciation and glacial refugia existed. However, a glacier extended from mainland North America to the shelfbreak in Dixon Entrance separating Alaska and the Queen Charlotte Islands. Glacial retreat to the east began sometime after 15,000 to 16,00014C yr B.P. and ice had completely left Dixon Entrance by 13,500 to 13,00014C yr B.P. A rapid sea-level regression occurred soon after deglaciation began, due to isostatic rebound, with relative sea level falling to approximately 150 m below present in central Dixon Entrance, decreasing the size of the inlet by about 30 percent by 12,40014C yr B.P. The late Quaternary glacial and postglacial stratigraphic sequence is more than 100 m thick overlying older Pleistocene sediments and Tertiary bedrock. A late Wisconsinan diamicton is overlain by glaciomarine muds formed between approximately 14,400 and 13,00014C yr B.P. Contemporaneous with the deposition of the glaciomarine muds an extensive outwash deposit formed off the northern coast of the Queen Charlotte Islands to a present depth of 150 m. During the sea-level lowstand and subsequent transgression, a reworked sand unit was deposited over much of the seafloor to depths greater than 450 m. The unit is exposed at the seafloor over much of the region, suggesting that seabed hydrodynamic energy levels were high after 13,00014C yr B.P. and remain so today.

New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

“…This interpretation is supported by previous work in the region; for example, radiocarbon-dated marine sediments suggest the outlet glacier occupying Dixon Entrance (Fig. 2) had receded to the modern coastline by ~14.5 cal ka BP (Barrie and Conway, 1999). Additionally, on southwestern Baranof Island (Fig.…”

New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

“…This interpretation is supported by previous work in the region; for example, radiocarbon-dated marine sediments suggest the outlet glacier occupying Dixon Entrance (Fig. 2) had receded to the modern coastline by ~14.5 cal ka BP (Barrie and Conway, 1999). Additionally, on southwestern Baranof Island (Fig.…”

Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada

“…An initial criticism of the coastal-migration theory is that the majority of the route was barred by the extensive Cordilleran Ice Sheet, which advanced to the shelf edge (Prest, 1969). However, this study and recent work (Blaise et al, 1990;Mann and Peteet, 1994;Heaton et al, 1996;Josenhans et al, 1997;Barrie and Conway, 1999;Fedje and Josenhans, 2000;Hetherington et al, 2003;Ward et al 2003;Hetherington et al, 2004) indicate that the LGM was less extensive and diachronous along the coast, allowing the possibility of human migration.…”

Estimation of in situ distribution of carbonate produced from cold-water octocorals on a Japanese seamount in the NW Pacific

“…Schuhmacher & Zibrowius (1985) proposed using the term 'constructional' for the organisms which form a bioherm that elevates a durable carbonate structure in shallow or deep water, and constructional forms are not necessarily hermatypic. The term 'constructional' could include other bioherm or biostrome constructor organisms such as sponges (Conway et al 1991, Barrie & Conway 1999, coralline algae (Bourrouilh- Le & Hottinger 1988, Carannante et al 1988, and of course the CWC Lophelia pertusa and its complexes (Mortensen et al 1995, Freiwald et al 2002. The results of the present study suggest that CWOC are azooxanthellate and ahermatypic but they also have the capabilities of constructional organisms such as shallow-water octocorals, which can make carbonate limestone with a maximum thickness of 22 cm (Konishi 1981).…”

New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

“…This interpretation is supported by previous work in the region; for example, radiocarbon-dated marine sediments suggest the outlet glacier occupying Dixon Entrance (Fig. 2) had receded to the modern coastline by ~14.5 cal ka BP (Barrie and Conway, 1999). Additionally, on southwestern Baranof Island (Fig.…”

Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada

“…An initial criticism of the coastal-migration theory is that the majority of the route was barred by the extensive Cordilleran Ice Sheet, which advanced to the shelf edge (Prest, 1969). However, this study and recent work (Blaise et al, 1990;Mann and Peteet, 1994;Heaton et al, 1996;Josenhans et al, 1997;Barrie and Conway, 1999;Fedje and Josenhans, 2000;Hetherington et al, 2003;Ward et al 2003;Hetherington et al, 2004) indicate that the LGM was less extensive and diachronous along the coast, allowing the possibility of human migration.…”

Estimation of in situ distribution of carbonate produced from cold-water octocorals on a Japanese seamount in the NW Pacific

“…Schuhmacher & Zibrowius (1985) proposed using the term 'constructional' for the organisms which form a bioherm that elevates a durable carbonate structure in shallow or deep water, and constructional forms are not necessarily hermatypic. The term 'constructional' could include other bioherm or biostrome constructor organisms such as sponges (Conway et al 1991, Barrie & Conway 1999, coralline algae (Bourrouilh- Le & Hottinger 1988, Carannante et al 1988, and of course the CWC Lophelia pertusa and its complexes (Mortensen et al 1995, Freiwald et al 2002. The results of the present study suggest that CWOC are azooxanthellate and ahermatypic but they also have the capabilities of constructional organisms such as shallow-water octocorals, which can make carbonate limestone with a maximum thickness of 22 cm (Konishi 1981).…”

New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

“…This interpretation is supported by previous work in the region; for example, radiocarbon-dated marine sediments suggest the outlet glacier occupying Dixon Entrance (Fig. 2) had receded to the modern coastline by ~14.5 cal ka BP (Barrie and Conway, 1999). Additionally, on southwestern Baranof Island (Fig.…”

Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada

“…An initial criticism of the coastal-migration theory is that the majority of the route was barred by the extensive Cordilleran Ice Sheet, which advanced to the shelf edge (Prest, 1969). However, this study and recent work (Blaise et al, 1990;Mann and Peteet, 1994;Heaton et al, 1996;Josenhans et al, 1997;Barrie and Conway, 1999;Fedje and Josenhans, 2000;Hetherington et al, 2003;Ward et al 2003;Hetherington et al, 2004) indicate that the LGM was less extensive and diachronous along the coast, allowing the possibility of human migration.…”

Estimation of in situ distribution of carbonate produced from cold-water octocorals on a Japanese seamount in the NW Pacific

“…Schuhmacher & Zibrowius (1985) proposed using the term 'constructional' for the organisms which form a bioherm that elevates a durable carbonate structure in shallow or deep water, and constructional forms are not necessarily hermatypic. The term 'constructional' could include other bioherm or biostrome constructor organisms such as sponges (Conway et al 1991, Barrie & Conway 1999, coralline algae (Bourrouilh- Le & Hottinger 1988, Carannante et al 1988, and of course the CWC Lophelia pertusa and its complexes (Mortensen et al 1995, Freiwald et al 2002. The results of the present study suggest that CWOC are azooxanthellate and ahermatypic but they also have the capabilities of constructional organisms such as shallow-water octocorals, which can make carbonate limestone with a maximum thickness of 22 cm (Konishi 1981).…”