Stable isotope paleoclimate studies in the western Basin and Range and greater Yellowstone region
详细信息 Stable isotope paleoclimate studies in the western Basin and Range and greater Yellowstone region
- 出版日期：2000.
- 页数：138 p. :
- 第一责任说明：Michael Andrew Poage.
- 分类号：a517
- ISBN：059989475X(ebk.) :
MARC全文
02h0023314 20110420154604.0 cr un||||||||| 110411s2000 xx ||||f|||d||||||||eng | AAI9983403 059989475X(ebk.) : CNY371.35 NGL NGL NGL a517 Poage, Michael Andrew. Stable isotope paleoclimate studies in the western Basin and Range and greater Yellowstone region [electronic resource] / Michael Andrew Poage. 2000. 138 p. : digital, PDF file. Source: Dissertation Abstracts International, Volume: 61-08, Section: B, page: 4045. ; Chair: C. Page Chamberlain. Thesis (Ph.D.) -- Dartmouth College, 2000. The paleorelief of mountain belts can be estimated from the δ 18O value of authigenic minerals. Development of relief during mountain building often creates lee-side rainshadows in which precipitation is depleted in 18O and deuterium. The magnitude of this “rain-shadow effect” is strongly correlated to relief. A compilation of δ 18O data from surface waters and precipitation throughout the globe shows a linear relationship between net elevation change and Δδ 18O (R2 = 0.79). Through the use of this relationship, and following a study of paleoelevation in the Southern Alps of New Zealand, we investigated the timing and magnitude of elevation change in the Sierra Nevada of California. The δ18O of smectites formed from weathering of volcanic ashes and currently exposed in sedimentary sections directly in the rainshadow of the modern Sierra show little change since 16 Ma. This suggests that these mountains have been a long-standing topographic feature, in accord with several recent studies challenging the long held view that the majority of Sierran topography developed post-10 Ma.;In a separate study, we establish oxygen isotope ratios of goethite from ferricrete chronosequences formed by natural acid rock drainage as a new source of spatially small-scale Holocene climate information. Oxygen isotope ratios of goethites from the mountainous northeastern Yellowstone region show an increase of -3‰ over the past 9000 years. We attribute this isotopic change to a local increase of isotopically heavier summer precipitation since the early Holocene, possibly augmented by seasonal temperature differences brought on by orbitally forced insolation changes over the past 9000 years. Our interpretation is compatible with palynology studies as well as Holocene climate simulations, which indicate a decrease in monsoon intensity from 9000 years B.P. to the present as well as progressively cooler summers. Unlike the southwestern United States, this change may have resulted in wetter summers in our study area. Paleoclimatology ; Paleoclimatology Sierra Nevada (Calif. and Nev.) ; Montana. Dartmouth College. aCN bNGL http://proquest.calis.edu.cn/umi/detail_usmark.jsp?searchword=pub_number%3DAAI9983403&singlesearch=no&channelid=%CF%B8%C0%C0&record=1 NGL Bs167 rCNY371.35 ; h1 bs1104