Lakes & Wetlands
Using Lake and Wetlands for Climate Records
Lakes and wetlands can host long records of climate and ecological changes. An integrated approach is required to access and understand the records.
LEFT: Swallow Lagoon, North Stradbroke Island, Queensland, Australia
Lakes and wetlands are depositional centers for sediment shed from the landscape. Typically we think of sand, silt and clay as sediment. However in lacustrine and palustrine environments, organic matter is a very important component of the sediments filling the basin. This mix of lithic and organic fragments can tell stories about how the watershed surrounding the lake/wetland has changed over time. Researchers are collecting sediment cores from such environments to look at details of the sedimentary record through analyzing specific components including: macro fossils, micro fossils, pollen, lithic sediment fraction, geochemical tracers and other palaeogeographic and palaeoclimactic indicators and proxies.
The members of the SDSU Quaternary Geology Lab augments this work by providing geomorphic and stratigraphic context to locations where researchers are collecting cores. We are also using shallow earth geophysics to apply sequence stratigraphic techniques to understand how water levels change and how these changes are linked to the palaeogeographic and palaeoclimactic proxies mentioned above.
Examples of Current Work
80 MHz GPR over water in action
The MALA GX 80 MHz GPR was placed in an inflatable raft and towed over a survey grid designed to image the sub-bottom stratigraphy of Brown Lake, North Stradbroke Island.
80 MHz GPR over water data clip
The MALA GX 80 MHz GPR produced amazing results. Brown Lake has maximum depths of ~6 m and the water column was easily penetrated with ample energy to image upwards of 20 m into the underlying sands with a vertical resolution of ~25 cm
80 MHz GPR over water interpretation
160 MHz GPR over wetlands in action
The MALA GX 160 MHz GPR was used to image the subsurface architecture of large wetlands on like Wellsby Lagoon, North Stradbroke Island.
160 MHz GPR over wetlands data clip
The MALA GX 160 MHz achieved well over 12 m of penetration into the wetland sediments. There are clear differences in the character that may relate to dune; dune-to-lake transition; lake; and wetland environments
160 MHz GPR over wetlands interpretation
Research Products from authors associated with the Lab
- Mazzone, S, Gontz, A, Moss, P, Tibby, J, Barr, C, Kelly, J and Marshall, J, 2019. Into the next dimension – coupling GPR, hydroclimate proxies and pollen to understand lacustrine records at Swallow Lagoon, Queensland, Australia. International Quaternary Association (INQUA) 20th Congress, Dublin, Ireland, 25-31 Jul 2019
- Mazzone, S, Gontz, A, Kelly, J, Tibby, J, Barr, C, and Marshall, J, 2019. Stratigraphic signatures of lake-level changes at Swallow Lagoon, North Stradbroke Island, Australia. Cordilleran Section Meeting, Geological Society of America, Portland, OR, 17-19 May 2019