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Abstract. At four sites in the central equatorial Pacific Ocean the flux of extraterrestrial 3He, determined using the excess 23øTh profiling method, is 8 x 10 -•3 cm • STP cm -2 ka -•. This supply rate is constant to within 30%. At these same sites, however, the burial rate of 3He, determined using chronostratigraphic accumulation rates, varies by more than a factor of 3.The lowest burial rates, which occur north of the equator at iøN, 139øW are lower than the global average rate of supply of extraterrestrial 3He by 20% and indicate that sediment winnowing may have occurred. The highest burial rates, which are recorded at the equator and at 2øS, are higher than the rate of supply of extraterrestrial 3He by 100%, and these provide evidence for sediment focusing. By analyzing several proxies measured in core PC72 sediments spanning the past 450 kyr we demonstrate that periods of maximum burial rates of 230 Th, 3He, løBe, Ti, and barite, with a maximum peak-to-trough amplitude of a factor of 6, take place systematically during glacial time. However, the ratio of any one proxy to another is constant to within 30% over the entire length of the records. Given that each proxy represents a different source (234U decay in seawater, interplanetary dust, upper atmosphere, continental dust, or upper ocean), our preferred interpretation for the covariation is that the climate-related changes in burial rates are driven by changes in sediment focusing.

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[1] Integrated Ocean Drilling Program (IODP) Site U1314 of the North Atlantic is a critical sedimentary archive record of subpolar deep water from the southern Gardar Drift for which we derived an age model of orbital resolution for the last 1.8 Ma. This chronology combined with high-resolution (cm scale) X-ray fluorescence core scanning measurements of major elements allows tracking changes in terrigenous provenance during the last 1.1 Ma. Low Potassium to Titanium (K/Ti) ratios reflect enhanced transport of basalt-derived titanomagnetites during warm climate intervals, while high K/Ti ratios indicate a dominance of acidic sediment sources typical for glacial and stadial events. Changes in K/Ti and magnetic concentration at Site 1314 are coeval with fluctuations in smectite content and grain size data from nearby piston cores, suggesting that the provenance changes are mainly controlled by variable flow of the Iceland-Scotland Overflow Water, an important branch of North Atlantic Deep Water. Furthermore, K/Ti variations on orbital time scales show a striking similarity to the deep sea d 13 C record from ODP Site 607. Pervasive features of the K/Ti time series during and after the Mid-Pleistocene Transition are suborbital changes similar to Dansgaard/Oeschger and Bond oscillations that appear to be strongly amplified during ice growth phases when global benthic d18 O was within the range of ∼4.1-4.6 per mil. The strong increase in variability of sediment provenance and subsequently deep hydrography at benthic d18 O values below ∼4.1 suggests that the extent of glaciations and, therefore, sea level corresponding to this value constitutes an important physical threshold that was persistent at least for the last 1.1 Ma.Citation: Grützner, J., and S. M. Higgins (2010), Threshold behavior of millennial scale variability in deep water hydrography inferred from a 1.1 Ma long record of sediment provenance at the southern Gardar Drift, Paleoceanography, 25, PA4204,

Thick deposits preserved in deep valleys in the Indus, Gilgit, and Hunza River Basins, and a variety of dates, allow new definition of Quaternary events in the Karakoram and Nanga ParbatHimalaya. An unusually long record for an actively eroding high mountain area is recognized in three major episodes of glaciation during Pleistocene time. An early glaciation is represented by the indurated lower Jalipur tillites and heterogeneous upper Jalipur valley-fill sedimentary rock younger than 1 to 2 Ma, which are folded, overturned, or overridden by rapid movement on the dextral-reverse Raikot fault. This is associated with high overall uplift rates of the Nanga Parbat-Haramosh massif during late Cenozoic time. The middle glaciation is represented by two tills intercalated within variable sediments, including thick lacustrine units dipping as much as 43° along the fault. The Indus-Shatial till of the early middle glaciation records the farthest advance of Pleistocene glaciers down the Indus River valley. The last glaciation apparently occurred after about 140,000 yr ago and consists of three to four or more separate advances, as recorded by morainic topography. The most prominent of these is the Dianyor moraine near Gilgit, which was produced by a major longitudinal glacier. Near Haramosh and downstream at Nanga Parbat, Shatial, and elsewhere, transverse glaciers blocked the Indus River to produce lake deposits now dipping as much as 6° near the fault. Catastrophic floods from failure of the ice dams, and possibly landslide dams as well, emplaced some Punjab erratics and sediments that may have been reworked into loesses and other sediments at the mountain front.on July 23, 2015 specialpapers.gsapubs.org Downloaded from

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Lacustrine algal carbonates, which form in shallow proglacial lakes, were found in most excavations into Bonney drift. Both in situ and reworked carbonate samples produced 49 new uranium/thorium (U/ Th) dates. U/Th dates of 70 to 130 ka for samples collected from excavations and natural sections, along with geomorphologic evidence reported elsewhere in this issue, confirm that the Bonney advance of Taylor Glacier, along with the concurrent expansion of local alpine glaciers, occurred during the interglaciation corresponding with marine isotope stage (MIS) 5. In addition, δ 18 O values (-35 to -43‰) of the algal carbonates confirm deposition in a proglacial lake fed by Taylor Glacier meltwater. The detailed distribution of U/Th dates shows that Bonney ice advances occurred in substages 5a, 5c, and 5e. The δ 18 O record of the Taylor Dome ice core also indicates ice thickening during these same intervals. The inclusion of older carbonates in Bonney drift affords evidence for proglacial lakes during MIS 7 (160 to 240 ka), MIS 9 (270 to 330 ka), and MIS 11 or older (>370 ka). It is probable that these proglacial lakes were also associated with interglacial expansions of Taylor Glacier. This terrestrial U/Th geochronology affords a regional constraint on the late Quaternary behavior of the peripheral sector of the EAIS drained by Taylor Glacier, consistent with expansion during global interglaciations and recession during global glaciations.