Implications for Life in the Subsurface

Geological Society of Minnesota  

GSM LECTURE, MONDAY, MARCH 9, 2009

At The University of Minnesota

Fluid Expulsion and Subsurface Sediment Transport: 

    Implications for Life in the Subsurface  

Karen Kleinspehn, PhD, Associate Professor, Earth Science Geology/Geophysics, University of Minnesota 

Date:  Monday, March 9, 2009      Lecture Begins:  7:30 PM

Location:  The University of Minnesota, East Bank, Electrical Engineering/Computer Science Bldg., Room 3-210

ABSTRACT: 

"Transport of sediment" typically focuses on sediment moved by wind, water or ice over the Earth's surface.  To the contrary, this talk will focus on sediment moved by fluids in the subsurface, sometimes several kilometers below the Earth's surface. The main variables include the compositions of moving pore fluids, microbial communities, pore-fluid pressures and the rates of fluid flow, the latter two of which will be the prime targets of this lecture. Observable features such as km-scale pockmarks and flaming mud mounds will be related to expulsion of fluids from the subsurface.  Speculations about the relationship between fluid expulsion and microbes at depth, the radiation of organisms, origins of life, climate change and large-scale geohazards will round out the presentation.

EDUCATION: PhD, 1982, Princeton University

RESEARCH INTERESTS: sedimentary geology/tectonics 

My research activities in the field of tectonics focus on geodynamics of continental lithosphere and the interactions between the lithosphere and atmosphere/hydrosphere. Consequently, I use surface processes in conjunction with structural geology, thermochronology (fission-track and Ar/Ar dating, vitrinite reflectance), trace-element geochemistry, and magnetostratigraphy to address problems of plate interactions in both neotectonic and ancient settings. Sedimentary basins are sensitive recorders of coupled lithospheric tectonics and atmospheric processes, and I use basins as a proxy to interpret plate kinematics.

One current projects deals with curved subduction zones and the effects of changing curvature on the geometry of the downgoing slab and 3-D internal deformation of fore-arc regions. We are evaluating syn-depositional deformation as a function of the plate-convergence vector with field areas in the Hellenic arc (Crete, Karpathos, Rhodos), Greece. By focusing on the vertical tectonic component recorded by sedimentary basins and by documenting the rates of exhumation, deformational style and kinematics, we will model the Pliocene-Recent mechanisms driving fore-arc deformation within an obliquely convergent plate margin.

Another project addresses the 80-million year evolution of the northwest corner of the Eurasian plate with a field area in Arctic Norway on the islands of Svalbard (Spitsbergen). Through a combined study of thermochronology, structural geology, sediment provenance and uplift rates, we assess the relative roles of continental rifting versus oblique convergence (transpression) in uplifting and exposing the outermost continental shelf anomalously above sea level.

    An on-going topic that emerged from this earlier Arctic study is syn-glacial uplift as an isostatic response to glacial erosion and transfer of large sediment loads beyond the flexural wavelength of continental lithosphere. Related aspects of this project include the origin of intraplate mountain belts, the origin of fjords and the degree of coupling across the boundary between continental and oceanic lithosphere. 

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