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A refined understanding of the paleoenvironmental history recorded at the Okanagan Centre section, an MIS 4 stratotype, south‐central British Columbia, Canada
Author(s) -
LESEMANN JEROMEETIENNE,
BRENNAND TRACY A.,
LIAN OLAV B.,
SANBORN PAUL
Publication year - 2013
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2665
Subject(s) - geology , stratotype , tephra , tephrochronology , outwash plain , deglaciation , subaerial , paleontology , unconformity , glacial period , geomorphology , marine isotope stage , paleosol , geochemistry , interglacial , stage (stratigraphy) , loess , sedimentary rock , volcano
The Okanagan Centre section is the stratotype for marine oxygen isotope stage (MIS) 4 sediments (Okanagan Centre Drift) in the southern interior of British Columbia, Canada. Previous work suggested that these sediments record two glacial and two interglacial cycles. This study reports on detailed sedimentological and geochronological investigations of lithostratigraphic units comprising the Okanagan Centre sequence, revealing successive deposition of subaqueous and subaerial outwash, a subglacial till and glaciolacustrine sediments during MIS 4. A limiting optical age of 113 ± 8 ka defines the base of this sequence. Sedimentological, paleopedological, optical dating and tephrochronological data from sediments near the middle of the sequence reveal soil development (MIS 3) in eolian sediments deposited on a river terrace overlying a deglaciated surface. Within these sediments, identification of Mt. St. Helens set C tephra suggest sedimentation between 50 and 35k 14 C a BP. Optical dating corroborates the tephrochronology and suggests that this surface formed after ∼52 ± 7 ka. The record of MIS 2 glaciation is restricted to deglaciation, and overlies MIS 3 sediments above an unconformity possibly related to regional subglacial meltwater erosion. Eolian sediments containing Mt Mazama set O tephra (∼7.62k cal a BP) cap the sequence.