Mineralogy and lithostratigraphy of Harris Lake, southwestern Saskatchewan, Canada

Abstract

Harris Lake, a small, groundwater fed lake in the Cypress Hills area of Saskatchewan, is one of the few lacustrine basins in the Great Plains that contains a complete, uninterrupted record of Holocene sedimentation. The lithostratigraphy and variation in the mineralogical composition of the sediments in this basin provide insight into the paleolimnology and paleohydrology of the lake and surrounding watershed. Although there is no evidence that the basin was dry for extended periods during the Holocene, the lake did experience numerous short-lived episodes of high salinity, as well as significant changes in solute composition during the early to mid-Holocene. An abrupt change, from a lake dominated by detrital sediments to one characterized almost entirely by endogenic deposition, occurred about 4000 years ago in response to the combined influence of forestation of the watershed and diversion of major fluvial and detrital influx by landsliding. These adjustments to the Harris Lake drainage basin were likely the result of the onset of cooler and wetter climatic conditions after 4500 B.P. During the late Holocene, slope failure continued to sporadically provide fresh clastic material to the otherwise endogenic-sediment dominated lake.