A Miocene to Pleistocene climate and elevation record of the Sierra Nevada (California)

Abstract

Orographic precipitation of Pacific-sourced moisture creates a rain shadow across the central part of the Sierra Nevada (California) that contrasts with the southern part of the range, where seasonal monsoonal precipitation sourced to the south obscures this rain shadow effect. Orographic rainout systematically lowers the hydrogen isotope composition of precipitation (␦D ppt) and therefore ␦Dppt reflects a measure of the magnitude of the rain shadow. Hydrogen isotope compositions of volcanic glass (␦D glass) hydrated at the earth's surface provide a unique opportunity to track the elevation and precipitation history of the Sierra Nevada and adjacent Basin and Range Province. Analysis of 67 well dated volcanic glass samples from widespread volcanic ash-fall deposits located from the Pacific coast to the Basin and Range Province demonstrates that between 0.6 and 12.1 Ma the hydrogen isotope compositions of meteoric water displayed a large (>40‰) decrease from the windward to the leeward side of the central Sierra Nevada, consistent with the existence of a rain shadow of modern magnitude over that time. Evidence for a Miocene-to-recent rain shadow of constant magnitude and systematic changes in the longitudinal climate and precipitation patterns strongly suggest that the modern first-order topographic elements of the Sierra Nevada characterized the landscape over at least the last 12 million years.climate ͉ hydrogen ͉ paleoaltimetry ͉ stable isotopes ͉ volcanic glass M ost of our knowledge of climate evolution is based on isotopic and paleontological data from the oceans. By contrast, terrestrial climate records are still sparse despite their paramount importance for our understanding of land-ocean climate connections and the impact of mountain ranges on late Cenozoic atmospheric circulation patterns. Here, we present the results of a hydrogen isotope study of hydrated volcanic glass that reconstructs the elevation and precipitation patterns of the Sierra Nevada (California) and Basin and Range Province (Nevada) over the last 12.1 Ma. Tephra erupted from the Snake River-Yellowstone hot spot sources, the Cascade Range, and volcanic sources east of the central and southern Sierra Nevada, as well as from other sources in the western United States, are a ubiquitous component of Miocene-to-recent sedimentary successions in the western United States and serve as important stratigraphic and time markers in the terrestrial geologic record (1-6). Explosive eruptions of tephra eject ash particles into the upper troposphere where winds distribute them rapidly over large areas. These ashes, almost instantaneously deposited at the earth's surface, are virtual time horizons, and the tephra layers therefore provide unique time-equivalent markers across almost the entire Cenozoic landscape of the western United States. Freshly erupted glass is nearly anhydrous (7), but within only thousands of years after deposition, rhyolitic volcanic glass deposited at the earth's surface incorporates large amounts of meteoric water (3-5 wt %) i...

Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes

“…Each of these materials retains the δ 18 O or δD composition of ancient meteoric waters (e.g. Lee-Thorpe and Van der Merwe, 1987;Cerling et al, 1993;Garzione et al, 2008;Mulch et al, 2008;Sachse et al, 2012). Especially for materials that capture shortterm variations in the isotopic composition of rainfall, the absence of systematic stable isotope-elevation relationships may render any paleoaltimetry interpretation complex, if not impossible (Blisniuk and Stern, 2005).…”

Miocene evolution of the western edge of the Nevadaplano in the central and northern Sierra Nevada: palaeocanyons, magmatism, and structure

“…They also discounted the importance of any palaeolatitudinal changes on climate, because the western USA has been at about the same latitude throughout the Cenozoic (Horton and Chamberlain 2006). Furthermore, Mulch et al (2008) have recently used hydrogen isotope data on hydrated glasses to infer that climate and precipitation patterns have not changed substantially over the last 12 Myr or more. Last, as argued above, it seems unlikely that climate change was the main control on the erosion of unconformity 2, because it is very strongly developed in the central Sierra, and is virtually absent in the northern Sierra; a change in climate would have presumably affected both the areas.…”

“…Evidence for significant late Cenozoic surface uplift includes tilting of Tertiary sedimentary units and river incision patterns (Christensen 1966;Huber 1981;Unruh 1991;Wakabayashi and Sawyer 2001;Jones et al 2004). However, recent studies have mainly used laboratory techniques to infer that the range has been a long-standing topographic feature of the landscape in the western USA, including stable isotope studies (Poage and Chamberlain 2002;Horton et al 2004;Horton and Chamberlain 2006;Mulch et al 2006); thermochronology (House et al 1998(House et al , 2001Clark et al 2005;Cecil et al 2006;Mahéo et al 2009); cosmogenic nuclide studies (Stock et al 2005); palaeobotanical studies (Wolfe et al 1997); dating of cave sediments (Stock et al 2004); and hydrogen isotope studies of widespread ash-fall deposits (Mulch et al 2008). Some workers, however, have proposed a more intermediate model, wherein a Cretaceous-Eocene inherited landscape surface began to undergo erosional rejuvenation sometime after 20 Ma (Clark et al 2005;Clark and Farley 2007;Pelletier 2007), in response to the inception of the Sierra Nevada microplate (Mahéo et al 2009;Saleeby et al 2009).…”

Eocene-Early Miocene paleotopography of the Sierra Nevada-Great Basin-Nevadaplano based on widespread ash-flow tuffs and paleovalleys

“…1; Henry, 2008;Cassel et al, 2009aCassel et al, , 2009bHenry and Faulds, 2010). The absolute elevation and structural-topographic evolution of this highland in the mid-Cenozoic remain highly controversial, however, particularly the paleoelevation of what is now the Sierra Nevada (Wakabayashi and Sawyer, 2001;Mulch et al, 2006Mulch et al, , 2008Cassel et al, 2009aCassel et al, , 2009bMolnar, 2010) and the timing of extension in northeastern Nevada, especially around the Ruby Mountains-East Humboldt Range metamorphic core complex (McGrew and Snee, 1994;Snoke et al, 1997;McGrew et al, 2000;Howard, 2003;Colgan and Henry, 2009;Druschke et al, 2009;Colgan et al, 2010;Henry et al, 2011;Mix et al, 2011).…”

“…Based on stable isotope and organic molecule paleothermometry and altimetry, together with detrital zircon geochronology, the Eocene-Oligocene Sierra Nevada is interpreted to have been at approximately the same elevation (~2.5-3 km at the latitude of Lake Tahoe) as it is today (Horton et al, 2004;Mulch et al, 2006Mulch et al, , 2008Cassel et al, 2009aCassel et al, , 2009bCecil et al, 2010;Hren et al, 2010). In contrast, Huber (1981), Unruh (1991), Wakabayashi and Sawyer (2001), Jones et al (2004), Stock et al (2004Stock et al ( , 2005, and Clark et al (2005) concluded from dated stream incision and gradients that the Sierra Nevada was much lower in the Eocene (≤1 km) and attained its present elevation following 1.5-2.5 km of uplift during the Late Miocene and Pliocene.…”