Establishing a multi-proxy approach to alpine blockfield evolution in south-central Norway

Abstract

Blockfields in high latitude mountain areas are a wide spread proxy for glaciation history. Their origin is debated since decades, especially in south-central Norway, where glaciation had a major global climate implication. Some authors explain old blockfield features by protection of cold-based ice, others claim they persisted as nunataks during the LGM (~20 kyr), or were formed throughout the Holocene. In order to clarify the origin of alpine blockfields we established a multi-method approach to combining lichenometry, stratigraphy, granulometry, and geochemistry (XRD, XRF). Our lichenometric dating results in conjunction with our factors indicate landscape stability for at least ~12.5 kyr. Frequent climatic shifts are evident in our profiles by varying color, LOI content and grain sizes. On the basis of geochemical analyses we were able to identify a long-term (chemical) weathering history and in situ blockfield formation. The field evidences and the climatic setting of the study area leave the possibility that our location was not covered by cold-based ice during the Late-Quaternary.

Schmidt-hammer exposure-age dating (SHD) performed on periglacial and related landforms in Opplendskedalen, Geirangerfjellet, Norway: Implications for mid- and late-Holocene climate variability

“…The glacial history of Scandinavia and the reconstruction of its past climate variability has been a research focus in excess of 100 years (e.g. Blytt, 1876; Hughes et al, 2016; Mangerud, 1991; Marr and Löffler, 2017; Patton et al, 2016, 2017; Stroeven et al, 2016). Much of the research conducted in (southern) Norway has explored glacier fluctuations aiming to understand climate variability since the Last Glacial Maximum (LGM, 26.5–20 ka, Clark et al, 2009; see Matthews, 2013; Nesje, 2009; Nesje and Dahl, 1993).…”