[Geysers] FW: UW-fac: Geologist to Talk on Yellowstone Lake

[Karen Low]

Thanks for the notification about the lecture.  For some reason the ENR department and the geology department don't communicate as well as they could.
 
I did go to the lecture.  The title on Lisa Morgan's first slide was actually "The floor of Yellowstone Lake is anything but quiet: Volcanic and Hydrothermal processes in a large lake above a Volcanic Caldera", which makes more sense since recent research has not shown an actual magma "chamber" under the park.  (See: http://faculty.gg.uwyo.edu/dueker/PAPERS/yellowstone%20discontinuities%20fee.pdf)
 
Dr. Morgan started with a brief volcanic history of the Snake River Plain and the Yellowstone hotspot.  She also mentioned the history of mapping of Yellowstone Lake (Hayden survey, Hague survey, and the 1991 mapping done by Kaplinski).  She mentioned that there is a large extremely deep hydrothermal vent near Stevenson Island.  Dr. Morgan went into detail on the five hydrothermal explosion craters throughout the lake, some completely under water (Mary Bay, Indian Pond, Elliot, Duck Lake, Franks crater), and explained that research was being done to determine if more features on the lake bottom were hydrothermal explosion craters.  She mentioned that 10% of the hydrothermal flux in the park, occurs through the lake, and that amount is analogous to Norris Geyser Basin.  She and her team mapped the caldera boundary where it runs through the lake, and a fault line from Eagle Bay to Lake Village.  She mentioned that the south half of the lake is dominated by glacial, erosive and
 sedimentary structures, while the north half is dominated by volcanic and hydrothermal structures.  She mentioned a fracture zone between Weasel Creek and Storm Point.  She explained about the breathing of the caldera moving the shorelines, and submerging older shorelines.  Dr. Morgan did go into detail about the elevated plain, with its release of H2S, which increases when lake levels are low due to lowered hydrostatic head.  She did mention the silicate spires with their diatoms and filamenteous bacteria.

The slides were amazing, and Dr. Morgan mentioned that maps of the lake bottom would probably go on sale this summer.  The ENR students seemed most interested in asking questions in how the mapping would effect studies on the Lake Trout population and on the bacteria of the spires.  
 
Karen Low
UW geology major, but I'll be back in the park for summer.

Bruce Alan Richardson <BRichard at uwyo.edu> wrote:
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Hi All,

Here’s a report on research that may be of interest.

Bruce Richardson

Casper, Wyoming

 

---------------------------------


From: Jill Meredith Lovato 
Sent: Tuesday, April 12, 2005 7:05 AM
To: uw-faculty at uwyo.edu; uwstaff-l at uwyo.edu
Subject: UW-fac: Geologist to Talk on Yellowstone Lake


 

Spring 2005 Student-Faculty Forum on the Environment and Natural Resources

 

Sponsored by the Haub School and Ruckelshaus Institute of Environment and Natural Resources

 

 

“Yellowstone Lake Is Anything But Quiet:  

Volcanic and hydrothermal processes in a large lake above an active magma chamber”

 

Lisa Morgan

Geologist

U.S. Geological Survey

 

Wednesday, April 13, 2005

12:00 Noon

Union Family Room

 

 

Discoveries from recent (1999-2003) multi-beam sonar mapping and seismic-reflection surveys of Yellowstone Lake provide new insight into the recent geologic forces that have shaped a large lake at the active front of the Yellowstone hot spot, a region strongly affected by young (<2 my), large-volume (>100-1000’s km3) silicic volcanism, active tectonism, and accompanying uplift.  Specifically, our mapping has identified the extent of postcaldera collapse volcanism and active hydrothermal processes occurring above a large magma chamber on the lake floor.  Multiple advances and recessions of thick glacial ice have overlapped the volcanic and hydrothermal activity leaving a lake basin that has been shaped predominantly by fire and ice.  Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes.  Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava 
 flows
 underlie much of Yellowstone Lake and exert fundamental control on lake morphology and localization of hydrothermal activity in the northern, West Thumb, and central basins.  Many previously unknown features have been identified and include over 300 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (~1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, large glacial melting features, incipient faulting along the trace of the Eagle Bay fault zone, and a recently active graben.  Sampling and observations with a submersible remotely operated vehicle (ROV) confirm and extend our understanding of the identified features.  Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustri
 ne
 landslides constitute potentially significant geologic hazards.  Fluids associated with active sublacustrine hydrothermal vent activity influence the geochemical composition of Yellowstone Lake water, which may significantly affect the Yellowstone ecosystem.

 

 

 

 

 

Jill Lovato

Project Coordinator/Academic Advisor

Ruckelshaus Institute and the Haub School

of Environment and Natural Resources

University of Wyoming

Dept. 3971

1000 E. University Avenue

Laramie, WY 82071

Ph: 307.766.5146

www.uwyo.edu/enr/ 

 

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