Extensive middle Miocene weathering interpreted from a well-preserved paleosol, Cricket Flat, Oregon, USA

Temperature seasonality in the North American continental interior during the Early Eocene Climatic Optimum

“…The bulk majorelement geochemistry of modern soils has been used to quantify the effects of weathering processes via a wide range of geochemical indices (see Sheldon and Tabor, 2009). The relationship between modern climate parameters like temperature and indices such as salinization (Sheldon et al, 2002), the paleosol weathering index (Gallagher and Sheldon, 2013), and the paleosol-paleoclimate model (Stinchcomb et al, 2016) has led to the development of climofunctions for MAT that have been used to estimate paleo-MAT during the Cenozoic (e.g., Retallack, 2007;Takeuchi et al, 2007;Bader et al, 2015;Stinchcomb et al, 2016). The clumped isotope ( 47 ) thermometer is based on the temperature-dependent relative enrichment of multiply substituted isotopologues of CaCO 3 ( 13 C 18 O 16 O 2 ) within the solid carbonate phase, which is independent of the isotopic composition of the water in which the carbonate precipitated (e.g., Ghosh et al, 2006;Eiler, 2007).…”

Paleoclimate Changes in the Pacific Northwest Over the Past 36,000 Years From Clumped Isotope Measurements and Model Analysis

“…The sites were prepared for sampling by excavating all visibly weathered or modern material from the surface of the soil profile in order to expose comparatively unaltered loess (Bader et al., 2015). The sites are not described in this study, but we do provide pedostratigraphic columns in Figure 2, because detailed descriptions already exist from previously published literature (Busacca, 1989; Busacca & McDonald, 1994; McDonald & Busacca, 1992).…”

“…Figure 2 depicts the loess‐paleosol sequences that were sampled, a legend describing their morphology, and the sampled depths. Since soils form from parent material by pedogenic processes that depend on local conditions (e.g., precipitation and heat flux) during the time of soil formation (Bader et al., 2015; Sheldon & Tabor, 2009), various proxy measurements of pedogenic carbonates have extensively been used as archives of paleoclimate data (Breecker et al., 2009; Cerling, 1984; Eagle et al., 2013; Passey et al., 2010; Peters et al., 2012; Quade et al., 2013; Sheldon & Tabor, 2009). Because paleosols containing pedogenic carbonate form over hundreds to thousands of years, their precipitation temperature depends primarily on the long‐term mean climate; thus, short‐term climatic variability does not overprint the long‐term conditions (e.g., regional cooling due to volcanism; Peters et al., 2012; Sheldon & Tabor, 2009).…”