The Last Glacial Maximum at 44°S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand

摘要: Abstract Determining whether glaciers registered the classic Last Glacial Maximum (LGM; ∼26,500–∼19,000 yrs ago) coevally between hemispheres can help to discriminate among hypothesized drivers of ice-age climate. Here, we present a record glacier behavior from Southern Alps New Zealand during ‘local LGM’ (LLGM). We used 10 Be surface-exposure dating methods and detailed glacial geomorphologic mapping produce robust chronology well-preserved terminal moraines deposited LLGM near Lake Ohau on central South Island. then glaciological model estimate snowline atmospheric temperature record. Seventy-three ages place culminations moraine construction, and hence completions advances positions outboard present-day Ohau, at 138,600 ± 10,600 yrs, 32,520 ± 970 yrs ago, 27,400 ± 1300 yrs 22,510 ± 660 yrs 18,220 ± 500 yrs ago. Recessional document recession into trough by 17,690 ± 350 yrs Exposure an ice-molded bedrock bench located inboard innermost 17,380 ± 510 yrs ago indicates that ice tongue had receded about 40% its overall length time. Comparing our with distances retreat suggests terminus mean net rate 77 m yr −1 surface lowered 200 m 17,690 17,380 yrs A long-term continuation in catchment is implied records head Irishman Stream valley, tributary valley. The cirque advanced set Lateglacial 13,000 ± 500 yrs implying was less extensive prior advance. employed model, fit these mapped dated moraines, derive elevations parameters modeling experiments indicate lowering 920 ± 50 m depression 6.25 ± 0.5 °C below modern values allows for grow equilibrium position within LGM belt. Taken together simulation reported snowlines temperatures increased least ∼520 m ∼3.6 °C, respectively, ∼18,000 ∼13,000 yrs Climate derived reconstruction are similar those Patagonia, air indicators Antarctica, as well sea-surface stratification signatures Ocean. think best explanation observed southern winter duration modulated Ocean sea ice, which turn influenced made ocean cooler. Orbitally induced cooling provides having been coincident northern LGM. argue further global effect North Atlantic stadials led disturbance stratification, southward shifts subtropical front, glaciers. Collapse Heinrich Stadial-1, along attendant warming, triggered onset termination Zealand.