Mary Leech Associate Professor of Geology

Geology photos

Research

My current focus is on high-grade rocks and migmatites from the Adirondack Highlands of New York. My research projects include the collisional processes of the Himalaya and gneiss domes of southern Tibet, coexisting pseudotachylyte and eclogite-facies shear zones in northern Norway, the tectonic evolution of the ultrahigh-pressure Qinling-Dabie-Sulu orogen in eastern China, and the tectonometamorphic history of subduction complexes in the Ural Mountains of Russia. I am a field geologist with research interests in geochronology, igneous and metamorphic petrology, structural geology and tectonics, and geochemistry.

 

Graduate Research Opportunities

(Application deadline for Fall admission: February 15, annually)

I am looking for students interested in research involving hard-rock petrology, geo/thermochronology, geochemistry, and tectonics on topics related to large-scale orogenic processes. I also encourage students to apply with interests in microstructural deformation processes using EBSD as a tool and/or students with interests in mineralogy and thermodynamic modeling using programs like Perple_X or THERMOCALC. Preference will be given to students with previous field, laboratory, and/or computer modeling experience. Please contact me for more information or see the Earth & Climate Sciences Department website or the Graduate Studies web site for program details and admissions requirements.

 

CURRENT GRADUATE STUDENTS

Jackson ReederJack Reeder

U-Pb SHRIMP geochronology and trace element chemistry of zirconsfrom Ledge Mountain, Adirondack Highlands, New York.

 

Lisa Simpson

Katherine "Katie" Sullivan

Age correlation of erupted plutonic clasts and Newberry volcanism: A window into the subterranean environment of a magmatic system.

 

Brandon SwansonBrandon Swanson

Migmatites from Ledge Mountain, Adirondack Highlands, New York.

 

FORMER STUDENTS

Rui Liu

Rui Liu (M.S. 2016)

Regional tectonic evolution of the Pioneer core complex, south-central Idaho (TBA)

Andy Nieblas

Andy Nieblas (M.S. 2016)

Pressure-temperature-time-deformation history of the Lahul valley, NW Indian Himalaya (Now working for Independent Geotechnical Consultants, Orange County, California)

Ozum Basta

Ozum Basta (M.S. 2015)

The tectonometamorphic evolution of the Greater Himalayan Sequence along the Zanskar shear zone, NW Himalaya (now a geologist with the Turkish Petroleum Corporation)

Emma Beck

Emma Beck (M.S. 2014)

P-T-t-d history of mylonites from the Zanskar shear zone, NW India (In transition from a position as a geologist with Occidental Petroleum)

Forrest Horton

Forrest Horton (M.S. 2011)

Geochronology and zircon geochemistry of Greater Himalaya leucogranites in Zanskar, NW India (now a post-doctoral researcher at CalTech)

Pariskeh Hosseini

Pariskeh Hosseini (M.S. 2011)

EBSD analysis of partially-eclogitized rocks from the Marun-Keu Complex, Polar Urals, Russia (now a PhD candidate at the City University of New York)

Deborah Shulman

Deborah Shulman (M.S. 2011)

Fluid controlled metamorphism of eclogitic pseudotachylite-bearing shear zones, Flakstadøy, northern Norway (Recently completed her PhD at the University of Maine)

Will Hassett

Will Hassett (M.S. 2010)

Geochemical signature of Himalayan gneiss domes: Implications for channel flow (now a contractor with the USGS)

 

Undergraduate Research Theses or Projects

Jennifer Luscombe (B.S. 2015)

P-T-t evolution of the UHP Tso Morari Complex, Indian Himalaya (Now in the graduate program at San Diego State University)

Ted Burlick (B.S. 2013)

Metamorphism of eclogites from the UHP Maksyutov Complex, south Ural Mountains, Russia (Now a graduate student at the Istanbul Technical Universtiy, Turkey)

Kelsey Kehoe (B.S. 2012)

Phase equilibria and thermobarometry of metabolites from Himalayan gneiss domes (Now in a PhD program at the University of Illinois Urbana-Champaign)

Carla Rosa (B.S. 2011)

Textural analysis of rocks from the Karakoram shear zone, Ladakh, northwestern Indian Himalaya (Now an Engineering Geologist with the California Geological Survey)

Kevin Denton (B.S. 2010)

Paleomagnetic study of the Caetano intra-caldera tuff, Lander County, Nevada (co-advised with Jonathan Glen; now a geophysicist at the USGS)

Steve Dutra (B.S. 2010)

Thermobarometry and mineral chemistry of clinopyroxenes in eclogite-facies shear zones in the Lofoten Islands, Norway

Mae Marcaida (B.S. 2010)

Crystallization history of Black Point and Red Cones: Mafic eruptions of the Mono-Inyo volcanic chain, eastern California (co-advised with Margaret Mangan, U.S.G.S. Menlo Park; now in the PhD program at Stanford University)

Molly Cornell (B.S. 2009)

Characterization of anomalous graphite from the Maksyutov ultrahigh-pressure metamorphic complex, Russia

Christina Polito (B.S. 2006)

Eclogitization of Proterozoic gabbros in the Lofoten Islands, Norway (Now at the Berkeley Geochronology Center)


CURRENT GRANT FUNDING

Currently writing a grant proposal to the Tectonics program at NSF for funding starting in time for the 2018 summer field season.

 

PREVIOUS GRANT FUNDING
NSF, 2009-2014 (extended through 2016), Petrogenetic affinity of Miocene granites to test the mid-crustal channel flow model in the Himalaya (in a no-cost extension)

NSF, 2010-2013, Upgrade of Electron Microscopy Facility to Increase Geoscience Functionality at San Francisco State University

NSF, 2008-2011, Acquisition of a FE-SEM to enhance research and student training in Biology, Chemistry, Geosciences, Physics, and Engineering at San Francisco State University
NSF, 2001-2005, Subduction and exhumation of ultrahigh-pressure rocks: Field and drilling studies in eastern China
NSF-AAAS, 2003-2004, Collaborative research on the petrotectonic evolution of the ultrahigh-pressure Tso Morari Crystallines, western Himalaya, India


LABORATORY FACILITIES IN GEOSCIENCES
Zeiss Ultra 55 Field emission scanning electron microscope with BSE, STEM detector, Oxford INCA EDS and EBSD (using Channel 5 software), and Gatan MiniCL. We use the SEM in conjunction with an XEI Evactron plasma cleaner and ibss Gentle Asher to maintain a clean sample chamber. Sample prepartion equipment includes a Gatan Model 682 PECS + RIBE that is a coater/ion beam etcher, a Cressington 208HR sputter coater, a Cressington 208C carbon coater equipped with sample holders specifically for geological thin sections, and a critical point dryer.
Mineral separation/sample preparation lab - Rock saws, thin sectioning equipment, grinder/polisher, vibratory polisher, jaw crusher, disk mill, shatterbox, slope Frantz magnetic separator, ovens, lap wheels, seives, rock storage
Bruker D8 ADVANCE powder x-ray diffractometer
• Various spectrometers, gas and liquid chromatographs, radiochemistry facilities and equipment, centrifuges, lasers, etc. (in the Department of Chemistry and Biochemistry)
• Scanning laser confocal microscope, fluorescence and epi-fluorescence microscopes, and a dissecting scope (in the Cell and Molecular Imaging Center, Department of Biology)
• Gas chromatograph stable isotope analyzer, elemental analyzer, etc. (at the Romberg Tiburon Center for Environmental Studies)
• Machine and glass shops, and an electronics repair facility

COURSES TAUGHT
Currently offered
Geochemistry* (Spring semesters - even years)
Global Tectonics (Spring semesters - odd years)
Mineralogy and Petrology I* (Spring semesters)
Mineralogy and Petrology II* (Fall semesters - even years)
Volcanology* (Fall semesters)


Offered in the past
Science Partners in K-12 Education

Tectonic Geomorphology*
The Violent Earth

Earthquakes and the San Andreas fault*

Geology of the National Parks
California Rocks!
* External users can contact me via e-mail for access to course materials on iLearn

 

Classroom exercises
Geologic provinces of the U.S. (with David Howell at the U.S. Geological Survey)


PUBLICATIONS


The Himalaya and southern Tibet (graduate student** co-author)
Leech, M.L. and Hassett, W.C.**, in review, Comparing three gneiss domes from the western and eastern Himalaya: The Leo Pargil, Renbu, and Yalashangbo domes, Contributions to Mineralogy and Petrology

Horton, F.** and Leech, M.L., 2013, Age and origin of granites in the Karakoram shear zone and Greater Himalaya Sequence, NW India, Lithosphere, doi:10.1130/L213.1

Klemperer, S.L., Kennedy, B.M., Sastry, S.R., Makovsky, Y., Harinarayana, T., and Leech, M.L., 2013, Mantle fluids in the Karakoram fault: Helium isotope evidence, Earth and Planetary Science Letters.

Leech, M.L., Klemperer, S.L., and Mooney, W.D., 2010, Proceedings for the 25th Himalaya-Karakoram-Tibet Workshop, San Francisco, California, U.S.A.: U.S. Geological Survey, Open-File Report 2010-1099, 242 p.

Leech, M.L., 2009, Reply to comment by M.P. Searle and R.J. Phillips (2009) and R.R. Parrish (2009) on: "Does the Karakoram fault interrupt mid-crustal channel flow in the western Himalaya?", Earth and Planetary Science Letters (2009), doi:10.1016/j.epsl.2009.05.039. This pdf also includes the two comments.

Leech, M.L., 2008, Does the Karakoram fault interrupt mid-crustal channel flow in the western Himalaya?, Earth and Planetary Sciences, 276, 314-322.

Leech, M.L., Singh, S., and Jain, A.K., 2008, Continuous metamorphic zircon growth and interpretation of U-Pb SHRIMP dating: An example from the western Himalaya: In, Metamorphic conditions along convergent plate junctions: Mineralogy, petrology, geochemistry, and tectonics (W.G. Ernst and D. Rumble III, eds.), Geological Society of America International Book Series, 10, 433-448.

Leech, M.L., Singh, S., Jain, A.K., 2007, Continuous metamorphic zircon growth and interpretation of U-Pb SHRIMP dating: An example from the western Himalaya, International Geology Review, 49, 313-328.

Leech, M.L., Singh, S., Jain, A.K., and Klemperer, S.L., and Manickavasagam, R.M., 2006, Reply to comment by P.J. O'Brien on: "The onset of India-Asia continental collision: Early, steep subduction required by the timing of UHP metamorphism in the western Himalaya", Earth and Planetary Science Letters, 245, 817-820.

Leech, M.L., Singh, S., Jain, A.K., and Klemperer, S.L., and Manickavasagam, R.M., 2005, The onset of India-Asia continental collision: Early, steep subduction required by the timing of UHP metamorphism in the western Himalaya, Earth and Planetary Science Letters, 234, 83-97.

 

Eastern China
Leech, M.L. and Webb, L.E., 2013, Is the HP-UHP Dabie-Sulu orogen a piercing point for offset on the Tan-Lu fault? Journal of Asian Earth Sciences, 63, 112-129.

Yang, T.N., Peng, Y., Leech, M.L., and Lin, H.Y., 2011, Fold patterns indicating Triassic constrictional deformation on the Liaodong peninsula, eastern China, and tectonic implications, Journal of Asian Earth Sciences, 40,72-83, doi:10.1016/j.jseaes.2010.08.017.

Leech, M.L., Webb, L.E., and Yang, T., 2006, Diachronous histories for the Dabie-Sulu orogen from high-temperature geochronology, Geological Society of America Special Paper 403, 1-22.

Webb, L.E., Leech, M.L., and Yang, T., 2006, 40Ar/39Ar thermochronology of the Sulu terrane: Late Triassic exhumation of high and ultrahigh-pressure rocks and other implications for Mesozoic tectonics in East Asia. Geological Society of America Special Paper 403, 77-92.

Yang, T., Xu, Z., and Leech, M.L., 2004, Mass balance during retrogression of eclogite-facies minerals in the Rongcheng eclogite, eastern Sulu UHPM terrane, China, American Mineralogist, 89, 1525-1532.

 

The Ural Mountains, Russia (undergraduate student* co-author)

Fedkin, V.V., Leech, M.L., Shchipansky, A.A., Valizer, P.M., Burlick, T.D.*, and Ernst, W.G., 2017, Coexisting zoned garnets and clinopyroxenes from mafic eclogites of the Maksyutov Complex, south Ural Mountains, Russia, Experiment in Geosciences, 23, 1-10.

Beane, R.J. and Leech, M.L., 2007, The Maksyutov Complex: The first UHP terrane 40 years later, in Cloos, M., Carlson, W.D., Gilbert, M.C., Liou, J.G., and Sorensen, S.S., eds., Convergent Margin Terranes and Associated Regions: A Tribute to W.G. Ernst: Geological Society of America Special Paper 419, p.153-169, doi: 10.1130/2006.2419(08).

Leech, M.L. and Willingshofer, E., 2004, Thermal modeling of an ultrahigh-pressure complex in the south Urals, Earth and Planetary Science Letters, 226, 85-99.

Bostick, B., Jones, R.E., Chen, C., Ernst, W.G., Leech, M.L., and Beane, R.J., 2003, Low-temperature microdiamond aggregates in the Maksyutov metamorphic complex, south Ural Mountains, Russia, American Mineralogist, 88, 1709-1717.

Leech, M.L., 2001, Arrested orogenic development: eclogitization, delamination, and tectonic collapse, Earth and Planetary Science Letters, 185, p. 149-159.

Leech, M.L. and Ernst, W. G., 2000, Petrotectonic evolution of the high- to ultrahigh-pressure Maksyutov Complex, Karayanova area, south Ural Mountains: Structural and oxygen isotope constraints, Lithos, 52, p. 235-252.

Leech, M.L. and Stockli, D.F., 2000, The late exhumation history of the ultrahigh-pressure Maksyutov Complex, south Ural Mountains, from new apatite fission track data, Tectonics, 19, p. 153-167.

Leech, M.L., 1999, Petrotectonic evolution of the Maksyutov Complex, south Ural Mountains, Russia, Ph.D. dissertation, Stanford University, 117 p.

Ernst, W.G., Mosenfelder, J.L., Leech, M.L., and Liu, J., 1998, H2O recycling during continental collision: phase-equilibrium and kinetic constraints. In When Continents Collide, eds., B.R. Hacker and J.G. Liou, Kluwer Academic, Netherlands, 275-295.

Leech, M.L. and Ernst, W.G., 1998. Graphite pseudomorphs after diamond? A carbon isotope and spectroscopic study of graphite cuboids from the Maksyutov Complex, south Ural Mountains, Russia. Geochimica et Cosmochimica Acta, 62, p. 2143-2154.

Beane R.J., Liou J.G., Coleman R.G., and Leech M.L., 1995, Mineral assemblages and P-T path for high- to ultrahigh-pressure metamorphism in the Maksyutov Complex, Ural Mountains, Russia, Island Arc, 4, p. 254-266.

Lennykh V.I., Valizer P.M., Beane R.J., Leech M.L., and Ernst W.G, 1995. Petrotectonic evolution of the Maksyutov Complex, south Urals, Russia: Implications for ultrahigh-pressure metamorphism, International Geology Review, 37, p. 584-600.


Norway
Leech, M.L. and Shulman, D.J., in review, Fluid-controlled metamorphism of eclogitic pseudotachylite-bearing shear zones, Flakstadøy, northern Norway, Journal of Metamorphic Geology.
Polito, C. and Leech, M.L., 2006, Petrology and new U-Pb SHRIMP dating for eclogues of the Lofoten Islands, Flakstadøy and Vestvagøy, northern Norway, Eos Transactions AGU, 87, Fall Meeting Supplement, Abstract V31A-0571.

 

Other publications

Leech, M.L., Howell, D.G., and Egger, A.E., 2004, A guided inquiry approach to learning the geology of the U.S., Journal of Geoscience Education, 52, 368-373.


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