Strontium isotope record of paleohydrology and continental weathering, Eocene Green River Formation, Wyoming

摘要: Sr isotope ratios in carbonate-rich lacustrine strata provide highly resolved and geo- graphically specific records of past changes weathering regional drainage patterns. The Eocene Green River Formation is perhaps the best documented pre-Quaternary la- custrine unit world; therefore, these are ideally suited for studying be- havior Sr. 87 Sr/ 86 measured primary carbonate lake expansion- contraction cycles Laney Member directly linked to changing facies. Four distinct preserved a 6.4 m interval Arco Washakie Basin No. 1 core, each represented by vertical succession transgressive stromatolite facies containing dolomicritic intraclasts, laminated micrite deposited during highstands, lake-marginal dolomicrite facies, which represent subsequent lowstands. Initial range from 0.711 99 0.713 31. least radiogenic compositions as- sociated with that increased runoff Phanerozoic marine Tertiary volcanic rocks highstands. most associated dolomicrite, recording higher pro- portion basin-bounding Precambrian uplifts exposed plain lowstand. observed variations may also be due part differential surrounding landscape, where drier climates decreased and, runoff.