A 900 k.y. record of strath terrace formation during glacial-interglacial transitions in northwest China

Dating of erosion surface and terraces in the eastern Qilian Shan, northwest China

“…All of the samples were measured on 2G-755 cryogenic magnetometers in magnetically shielded conditions and were progressively demagnetized to 600°C or to 600 Oe. Similar to previous results (Pan et al, 2003), secondary magnetizations are effectively removed by 250-300°C or 300 Oe so that the characteristic remanence directions are clearly identifiable at temperatures of more than 300°C or alternating field strengths of 300 Oe. The results shown here follow demagnetization in a peak field of 350 Oe.…”

“…There are five terraces in Shagou River (Pan et al, 2003). All of them are bedrock-seated terraces except for T 1 , which is an accumulation terrace.…”

“…Nevertheless, there is no current consensus on the specific timing of incision that precedes the formation of terraces. Previous researchers proposed several controversial mechanisms, suggesting that down-cutting may occur in cold glaciations (Molnar et al, 1994;Reusser et al, 2004), during transitions from glacial to interglacial conditions Pan et al, 2003), and with non-glacial phenomena, such as monsoon intensification (Pratt et al, 2004). Therefore, a more detailed study on the timing of terrace formation entails an in-depth evaluation of the various dating methods used to construct the bases of terrace sequences and subsequent regional tectono-climatic correlations.…”

“…Sequences of terrestrial loess deposits have been used as effective stratigraphic markers of dating significance. Therefore, the basal age of loess deposits overlying a terrace, when used in combination with other absolute dating methods, can provide a realistic estimate of the timing of terrace formation, provided that the time lag between the abandonment of terrace and the onset of loess deposits is minimal and thus is relatively negligible (Li et al, 1997;Pan et al, 2003;Porter et al, 1992).…”

Multi-phased uplift of the southern margin of the Central Anatolian plateau, Turkey: A record of tectonic and upper mantle processes

“…Studies of dated terrace sequences in active tectonic settings worldwide have noted that although sustained surface uplift is required for development of stepped strath terrace sequences, stages of individual terrace formation or abandonment tend to cluster during periods of known climate change (e.g., Bookhagen et al, 2006b;Bridgland and Westaway, 2008;Bull, 1991;Fuller et al, 1998;Lavé and Avouac, 2001;Merritts et al, 1994;Pan et al, 2003;Pazzaglia and Brandon, 2001;Pazzaglia and Gardner, 1993;Schildgen et al, 2002;Pazzaglia, 2002, 2009). This clustering likely results from climate-induced changes in sediment and water flux with associated changes between vertical and lateral channel incision, which has been shown to be necessary for strath formation and abandonment (Bogaart et al, 2003;Hancock and Anderson, 2002;Meyer et al, 1995;Tucker and Slingerland, 1997).…”