| Abstract Detail
Beringia!: Current Insights on the Geology, Climate, Paleontology, Floristic Assembly, and Biodiversity of a Subcontinent that is Central to Northern Hemisphere Biogeography Bond, Jeffrey [1]. Paleogeography and geology of Beringia. For the past 40 million years, Beringia has connected the North America and Asia continents. Its paleo-geographic evolution begins with the breakup of the supercontinent Rodinia, 750 million years ago, and the establishment of an ocean-continent boundary 500 million years ago. Mountains emerge between 195 and 60 million years ago through the addition of offshore landmasses (accretion) to the continents and surface uplift (Colpron and Nelson, 2021). By 40 million years ago, a mountain belt connected Asia and North America, facilitating the passage of plants and animals between the landmasses. Disconnection of the land bridge and reconnection of the Bering Strait, likely occurred for a period during the Pliocene, 5 to 3 million years ago. Following the Pliocene, Beringia enters its most dynamic phase. With the onset of the Pleistocene 2.6 million years ago, shifts between glacial and interglacial climates become the norm. During interglacial periods, with sea levels reaching present-day extents, a strait divides Beringia and connects the Pacific and Arctic oceans. Conversely, during glacial periods, sea level fell by as much as 120 m (400 ft), exposing the continental shelf and re-establishing the land bridge between the continents. This happened dozens of times during the Pleistocene. During the height of the last glaciation 20,000 years ago, Beringia measured 1200 km (750 miles) across from the Pacific to the Arctic Ocean.
Despite the immensity of the sub-continent, the paleo-geography of the landscape during glacial periods has remained relatively obscure. In 2016, Danielson et al. published a new bathymetric compilation for the continental shelf between North America and Asia. This compilation provided the first opportunity to analyze the Beringian landscape. In 2019, the Yukon Geological Survey acquired the bathymetric data in order to build an improved map of Beringia. Prominent lakes and rivers were mapped with the newly acquired data and resulted in the publishing of a new paleo-drainage map of Beringia (Bond, 2019). The improved topographic map also allowed us to visualize the flooding process during deglaciation, and understand where the last connection points remained during the Pleistocene to Holocene transition.
This talk will focus on Beringia’s geology and paleogeography extending back 500 million years. The Pleistocene geography of Beringia will be described using the recently released paleo-drainage map, which has implications for understanding the surficial geology and soils of the landscape.
References:
Bond, J.D., 2019. Paleodrainage map of Beringia. Yukon Geological Survey, Open File 2019-2
Colpron, M. and Nelson, J.L., 2021. Northern Cordillera: Canada and Alaska. An update In: Encyclopedia of Geology, North America, edited by Selley, R.C., Cocks, R.M., Plimer, I.R. Elsevier Ltd.
Danielson, S.L., Dobbins, E.L., Jakobsson, M., Johnson, M.A., Weingartner, T.J., Williams, W.J. and Zarayskaya, Y., 2016. Sounding the northern seas, Eos, 96, doi:10.1029/2015EO040975.
Related Links:
Paleodrainage map of Beringia
1 - Government of Yukon, Yukon Geological Survey, Box 2703 (k-102), Whitehorse, Yukon, Y1A2C6, Canada
Keywords:
Beringia
Paleogeography
Geology
Paleodrainage
Surficial geology
soils.
Presentation Type: Symposium Presentation
Number: S1002
Abstract ID:761
Candidate for Awards:None |
