Colloquium Series Speakers

Upcoming

Please join us for Earth Sciences' first colloquium event. 

Date: Tuesday, September 27, 2022
Time: 1:30 PM
Location: BGSB 1053

Dr. Yongsong Huang (Professor of Earth, Environmental and Planetary Sciences, Brown University) New quantitative paleo-proxies for temperature, sea ice and salinity based on alkenones produced by phylogenetically distinct Isochrysidales species 

Abstract

Long chain alkenones are arguably the most accurate paleotemperature thermometers ever developed. In contrast to isoprenoidal and branched GDGTs, alkenones have much better defined producing organisms (order Isochrysidales of Haptophye algae) and well demonstrated linear temperature correlations based on laboratory growth and global ocean coretop sediment transects. Alkenones are diagenetically highly stable biomarkers hence well suited for paleo-reconstructions. Unsaturation indices of alkenones have been widely and successfully applied for paleotemperature reconstructions for ~ 40 years. Recent studies, however, demonstrate that Isochrysidales are also well adapted to grow in different salinity, stretching all the way from freshwater to hypersaline waters. Salinity (as well as dynamics of salinity during the growth season) is the predominant control on the Isochrysidales speciation. Genomic analyses on seasonal water and sediment samples reveal well defined salinity niches when specific Isochrysidales species flourish. While Isochrysidales respond to temperature changes primarily by adjusting the number of double bonds in alkenones, salinity induced changes in alkenones (and alkenoates) are also reflected by systematic changes in double bond positions, chain length characteristics, resulting from transitions among different Isochrysidales species. Such salinity-induced response is markedly different from the physiological response of alkenone unsaturation ratios of individual Isochrysidales species to temperature. In this presentation, I will review our discovery of freshwater Isochrysidales and associated alkenones, phylogenetic classifications of different groups and sub-groups of Isochrysidales, improvement of alkenone analytical methods and efforts to calibrate alkenone and alkenoate chemotaxonomical changes to salinity, temperature changes. The refined chemotaxonomy has been carried out using laboratory culture experiments, natural surface sediment transects, and estuaries and lakes of wide range of salinity from fresh to hypersaline. I will also discuss a series of paleosalinity and paleohydrological reconstructions from lacustrine and ocean environments, including the Balck Sea salinity reconstruction during deglacial and sea ice reconstruction from LGM to present in Nordic Seas. 

 

Dr. Rachel Newrick (CSEG) Exploration Geophysicist and Instructor, Racian Ventures 403-464-3224

Date: Friday, October 21, 2022
Time:
TBA
Location:
TBA

 

Dr. Erin Adlakha (St. Mary's University)

Date: Tuesday, November 29, 2022
Time: TBA
Location: TBA

 

There will not be a colloquium event in December 2022.

 

January - TBA

 

Ananya Mallik (Dept. Geoscience, University of Arizona, AZMSA

Date: February
Time:
TBA
Location:
TBA

 

March - TBA