QUANTITATIVE RECONSTRUCTION OF ANCIENT CLIMATIC PARAMETERS FOR MIOCENE CLARKIA FOSSIL LAGERSTäTTE

The Miocene Clarkia fossil deposit in northern Idaho was discovered in 1972. During the past ~40 years, extensive studies have been carried out on the extremely well-preserved fossil materials from this site, known as fossil lagerstätte. Its well-studied geological and geophysical setting, age, complete list of fossils, etc. have been published, along with the discovery of suites of ancient biomolecules from fossil plants of this site, making it one of the world most important fossil sites to examine Cenozoic plant evolution, fossil taphonomy, and paleoclimate. Ancient climate of this middle Miocene age flora has been established, based upon the composition of the flora, but little quantitative reconstruction of specific climatic parameters has been conducted. During the past decades, several quantitative methods of reconstructing ancient climates on plant remains, identifiable or non-identifiable, have been proposed, including, for example, LMA - Leaf Margin Analysis, LAA - Leaf-Area Analysis, CLAMP - Climate Leaf Analysis Multivariate Program, and DLP - Digital Leaf Physiognomy. The CA - Coexistence Approach on identifiable plant remains is considered more preferable as it is established upon the modern climate tolerant ranges of fossils’ NLRs (Nearest Living Relatives). We apply the CA method to plant taxa of this fossil site which is obtained from published sources as well as our own data set. Quantitative reconstruction of climatic parameters such as mean annual temperature, temperature of the warmest month, temperature of the coldest month, mean annual precipitation, mean relative humidity, potential evaporation, mean annual precipitation, mean maximum monthly precipitation, mean minimum monthly precipitation, mean precipitation of the warmest month, and aridity are presented based upon the most up to date Clarkia flora composition. The results are compared with previously published analyses under the context of middle Miocene global climate background.