Holocene Environmental Change and Human Impact in Hoya Rincon de Parangueo, Guanajuato, Mexico

Abstract

This paper presents a paleoenvironmental study on Hoya Rincon do Parangueo, a maar lake in Valle de Santiago in Central Mexican Bajio. Maar lake sediments have been widely used for high-resolution reconstruction of paleoenvironment. Many different paleoenvironmental proxy data such as stable isotopes, pollen, sediment chemistry, and dung fungus spore were produced in this study. The pine-oak ratio, stable isotopes, and sediment chemistry help to reveal paleoenviromental changes throughout the whole period covered by sediment materials from this study site. The evidence I found indicates that during ca. 9,500 <TEX>$\sim$</TEX> ca. 8,300 cal yr B.P. there was dry climate; during ca. 8,300 <TEX>$\sim$</TEX> ca. 6,300 cal yr B.P. it was wetter; during ca. 6,300 <TEX>$\sim$</TEX> ca. 4,000 cal yr B.P. drier and cooler; during ca. 4,000 <TEX>$\sim$</TEX> ca. 1,100 cal yr B.P. milder and wetter. The presence of Chupicuaro culture between ca. 2,500 <TEX>$\sim$</TEX> 1,100 cal yr B.P. is implied by the high frequencies of Amaranthaceae and Zea mars. It seems that man left this lake around 1,100 cal yr B.P. due to a dry climate after 1,300 cal yr B.P. Spanish arrival around 400 cal yr B.P. is implied by the fact that fe3 mars reappears and Sporormiella spp. become significant around 120 cm, whereas Poaceae drops sharply.