Abstract. The initiation and evolution of the Cordilleran Ice Sheet are relatively poorly constrained. International Ocean Discovery Program (IODP) Expedition 341 recovered marine sediments at Site U1417 in the Gulf of Alaska (GOA). Here we present alkenone-derived sea surface temperature (SST) analyses alongside ice-rafted debris (IRD), terrigenous, and marine organic matter inputs to the GOA through the late Pliocene and early Pleistocene. The first IRD contribution from tidewater glaciers in southwest Alaska is recorded at 2.9 Ma, indicating that the Cordilleran Ice Sheet extent increased in the late Pliocene. A higher occurrence of IRD and higher
sedimentation rates in the GOA during the early Pleistocene, at 2.5 Ma,
occur in synchrony with SSTs warming on the order of 1 ∘C relative
to the Pliocene. All records show a high degree of variability in the early
Pleistocene, indicating highly efficient ocean–climate–ice interactions
through warm SST–ocean evaporation–orographic precipitation–ice growth
mechanisms. A climatic shift towards ocean circulation in the subarctic
Pacific similar to the pattern observed during negative Pacific Decadal
Oscillation (PDO) conditions today occurs with the development of more extensive Cordilleran glaciation and may have played a role through increased moisture supply to the subarctic Pacific. The drop in atmospheric CO2 concentrations since 2.8 Ma is suggested as one of the main forcing mechanisms driving the Cordilleran glaciation.
Late Quaternary Stable Isotopic Stratigraphy of Hole 910A, Yermak Plateau, Arctic Ocean: Relations with Svalbard/Barents Sea Ice Sheet History
