Mary Leech

Published peer-reviewed papers:

Adirondack Highlands & the Grenville orogen

• Metzger, E.P., Leech, M.L., *Davis, M., *Reeder, J., *Swanson, B., and Waring, H., 2021, Ultrahigh-temperature granulite-facies metamorphism and exhumation of deep crust in a migmatite dome during late- to post-orogenic collapse and extension in the central Adirondack Highlands, Geosphere.
• **Davis, M., Leech, M.L., and Metzger, E.P., 2020, Kyanite-Bearing Migmatites at Ledge Mountain, Adirondack Highlands, American Geophysical Union, Fall Meeting Supplement, Abstract V019-0004.
• **Davis, M., Leech, M.L., and Metzger, E.P., 2020, Determining the petrotectonic evolution of Ledge Mountain migmatites with phase equilibria modeling and melt reintegration: Adirondack Highlands, New York, Geological Society of America Abstracts with Programs, 52, 6, doi: 10.1130/abs/2020AM-358255. 
• Leech, M.L., Metzger, E.M., and **Swanson, B., 2019, Evidence for ultrahigh-temperature (UHT) metamorphism in the Adirondack Highlands, Geological Society of America Annual Meeting, Abstract T23-4-11, doi: 10.1130/abs/2019AM-339742.
• Leech, M.L., *Swanson, B., and Metzger, E., 2017, Kyanite-bearing migmatites at Ledge Mountain, Adirondack Highlands, American Geophysical Union, Fall Meeting Supplement, Abstract V31B-0512.
• *Reeder, J., Metzger, E., Bickford, M.E., Leech, M.L., and Waring, H., 2016, Kyanite-bearing migmatites in the central Adirondack Mountains: Implications for late- to post-orogenic metamorphism and melting in a collisional orogen, American Geophysical Union, Fall Meeting Supplement, Abstract V23D-3009.
• *Reeder, J., Metzger, E., Bickford, M.E., and Leech, M.L., 2016, Kyanite-bearing migmatites in the central Adirondack Mountains: determining a P-T-t path and its implications on conceptual models, Geological Society of America Abstracts with Programs, Vol. 48, No. 7, Paper No. 336-12, doi: 10.1130/abs/2016AM-285430.

The graphite-diamond transition & diamond preservation in UHP rocks

• Sonin, V., Leech, M.L., Chepurov, A., Zhimulev, E., and Chepurov, A., 2018, Why are diamonds preserved in UHP metamorphic complexes? Experimental evidence for the effect of pressure on diamond graphitization, International Geology Review, doi:10.1080/00206814.2018.1435310.
• 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. 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.

The Himalaya and southern Tibetan plateau 

• Leech, M.L. and Hassett, W.C.**, in revision, Comparing three gneiss domes from the western and eastern Himalaya: The Leo Pargil, Renbu, and Yalashangbo domes.
• 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" by Mary L. Leech, S. Singh, A.K. Jain, Simon L. Klemperer and R.M. Manickavasagam, Earth and Planetary Science Letters 234 (2005) 83-97, 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.

The Dabie-Sulu orogen in 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 

• Fedkin, V.V., Burlick, T.D.*, Leech, M.L., Shchipansky, A.A., Valizer, P.M., , and Ernst, W.G., 2021, Petrotectonic origin of mafic eclogites from the Maksyutov subduction complex, south Ural Mountains, Russia, Geological Society of America, Special Paper in Honor of Eldridge M. Moores (edited by J. Wakabayashi, Y. Dilek, and Ogawa).
• 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 considerations. 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, Petrology and retrograde P-T path for eclogites of the Maksyutov Complex, southern 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.

Eclogitization & the  role of fluids in brittle-ductile processes, Norway

• Leech, M.L. and Shulman, D.J., in revision, Fluid-controlled metamorphism of eclogitic pseudotachylite-bearing shear zones, Flakstadøy, northern Norway.
• Leech, M.L. and **Shulman, D.J., 2014, Fluid-controlled eclogitization of pseudotachylyte-bearing shear zones, Flakstadøy, Norway, Goldschmidt conference abstract, 22f-302.
• Leech, M.L. and **Shulman, D.J., 2012, Fluid-controlled metamorphism of eclogitic pseudotachylite-bearing shear zones, Flakstadøy, northern Norway, Eos Trans., Am. Geophys. Union, Fall Meeting Supplement, Abstract MR51A-03.
• *Dutra, S.M., **Shulman, D.J., and Leech, M.L., 2010, Thermobarometry of eclogites-facies shear zones in the Lofoten Islands, Norway, Geol. Soc. Am. Abstr. Prog., 42,  p. 100.
• Leech, M.L., **Shulman, D., and *Dutra, S., 2009, Pseudotachylite in eclogite-facies shear zones from the Lofoten Islands, northern Norway, Eos Trans., Am. Geophys. Union, Fall Meeting Supplement, Abstract V43C-2265.
• **Shulman, D., Leech, M.L., and *Dutra, S., 2009, Eclogite-facies pseudotachylite in deep crustal rocks exposed in northern Norway, Geol. Soc. Am. Abstr. Prog., 41, p. 485.
• *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.

Cordilleran gneiss domes

• **Liu, R. and Leech, M.L., 2016, Regional tectonic evolution of the Pioneer metamorphic complex, south-central Idaho, Am. Geophys. Union, Fall Meeting Supplement, Abstract #T51F-2994.

Other publications - Education-related

• 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.

(**graduate student and *undergraduate student co-authors)

My current research projects include ca. 1 Ga ultrahigh-temperature metamorphism and migmatization in the Adirondack Highlands, New York; ca. 53 Ma ultrahigh-pressure subduction zone metamorphism in the India-Asia collision zone, and Miocene granite intrusion and mid-crustal channel flow processes in kyanite-bearing Greater Himalaya Sequence rocks, India; and the interplay between britle and ductile deformational processes in pseudotachylyte-bearing eclogite-facies shear zones in the Lofoten Islands, Norway.

External grants

1. U.S. Geological Survey EDMAP program (2020-2021) part of the National Cooperative Geologic Mapping Program, “Geologic mapping of the Ledge Mountain migmatites, Rock Lake 7.5’ quadrangle, Adirondack Highlands, New York” (extended 1 year because of Covid-19 restrictions on research/travel), PI

2. NSF Tectonics program (2013-2014) EAR 1406054, “Microstructural Analysis and EBSD Applications in Earth Sciences” (workshop using David Mainprice's MTEX/MATLAB), PI

3. NSF Instrumentation & Facilities (2010-2013) EAR 0949176, Upgrade of Electron Microscopy Facility to Increase Geoscience Functionality at San Francisco State University, PI

4. NSF Continental Dynamics (2010-2011) EAR 0965796, “Conference Support for the 25th International Himalaya-Karakoram-Tibet (HKT) Workshop” and “Future directions for NSF-sponsored geoscience research in the Himalaya/Tibet”, PI

5. NSF CAREER — Tectonics, Petrology & Geochemistry, and Education and Human Resources (2009-2014) EAR 0847721, Petrogenetic affinity of Miocene granites to test the mid-crustal channel flow model in the Himalaya (two no-cost extensions to 2016), PI

6. NSF Major Research Instrumentation (2008-2011) CHE 0821619, Acquisition of a FE-SEM to enhance research and student training in Biology, Chemistry, Geosciences, Physics, and Engineering at San Francisco State University, Co-PI

7. NSF-AAAS Women's International Science Collaboration grant (2003-2004) Collaborative research on the petrotectonic evolution of the ultrahigh-pressure Tso Morari Crystallines, western Himalaya, India, PI

8. NSF Continental Dynamics (2001-2005) EAR 0003355, Subduction and exhumation of ultrahigh-pressure rocks: Field and drilling studies in eastern China, ~20% of proposal effort

9. University of California President's Postdoctoral Fellowship Program (2001-2003) The impact of eclogite formation on the dynamics of continental collision

10. NSF Office of International Science and Engineering (1999-2001) OISE 9901573, Mountain building in the Urals and the nature of ultrahigh-pressure metamorphism, PI

Current students

Graduate students

• Laura Horsley (M.S. exp. 5/2022) U-Pb SHRIMP dating and phase equilibria modeling of Ledge Mountain migmatites, Adirondack Highlands, New York
• Zachary Smirnov (M.S. exp. 5/2023) Thermodynamic modeling of ultrahigh-temperature granulites in the Ledge Mountain region, Adirondack Highlands, New York

Undergraduate students

• Victoria "Tori" Hicks (B.S. exp. 2023)
• Grayson Kohary (B.S. exp. 2023)
• Kaitlyn "Kei" Mowry (B.S. exp. 2023)

Former students

Graduate students

• Mike Davis (M.S. exp. 5/2021) Petrotectonic evolution of Ledge Mountain migmatites with phase equilibria modeling and melt reintegration, Adirondack Highlands, New York (Now a Research Assistant at the U.S. Geological Survey, Menlo Park)
• Brandon Swanson (M.S. 2018) Pressure-temprature conditions of Kyanite-bearing Migmatites at Ledge Mountain, Central Adirondack Highlands (Now a Hydrologist at Nevada Gold Mines, Elko, NV)
• Katherine "Katie" Sullivan (M.S. 2017) Correlation of erupted plutonic clasts and volcanic deposits from Newberry volcano, Oregon (Now a contractor for the US Geological Survey, Menlo Park, CA)
• Jackson Reeder (M.S. 2017) U-Th-Pb geochronology and trace element chemistry of zircon from Ledge Mountain, central Adirondack Highlands, New York (Now a Geologist at Amec Foster Wheeler, Oakland, CA)
• Rui Liu (M.S. 2016) Regional tectonic evolution of the Pioneer core complex, south-central Idaho (Now a Geologist at StructureSolver LLC, Houston, Texas)
• Andy Nieblas (M.S. 2016) Pressure-temperature-time-deformation history of the Lahul valley, NW Indian Himalaya (Now a Senior Staff Geologist at LGC Geotechnical, Inc., San Clemente, CA)
• Ozum Basta (M.S. 2015) The tectonometamorphic evolution of the Greater Himalayan Sequence along the Zanskar shear zone, NW Himalaya (Now a Reservoir Geologist at Turkish Petroleum, Ankara, Turkey)
• Emma Beck (M.S. 2014) P-T-t-d history of mylonites from the Zanskar shear zone, NW India (Now an MBA Candidate at Harvard Business School)
• Forrest Horton (M.S. 2011) Geochronology and zircon geochemistry of Greater Himalaya leucogranites in Zanskar, NW India (Completed his PhD in Geological Sciences at UC Santa Barbara in 2015. Now an Assistant Scientist at Woods Hole Oceanographic Institution)
• Pariskeh Hosseini (M.S. 2011) EBSD analysis of partially-eclogitized rocks from the Marun-Keu Complex, Polar Urals, Russia (Now a PhD candidate at Queens College, City University of New York)
• Deborah Shulman (M.S. 2011) Fluid controlled metamorphism of eclogitic pseudotachylite-bearing shear zones, Flakstadøy, northern Norway (Completed a PhD in Geology in 2016 at the University of Maine. Now an Event Coordinator, University of Maine)
• Will Hassett (M.S. 2010) Geochemical signature of Himalayan gneiss domes: Implications for channel flow (Now a teacher with Teach for America)

Research facilities in the Department of Earth & Climate Sciences include:

• 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, sieves and sieve shakers, rock storage

• Twenty Leica DM750P petrographic microscopes available for student use, and one trinocular Leica DM750P scope with a dedicated 18 megapixel DSLR camera with HD video recording (Canon EOS Rebel T3i) for taking photomicrographs or videos of thin sections.

• Leech’s personal lab has a Nikon E600POL polarizing microscope and a Nikon SMZ1500 reflected and transmitted light microscope with a polarizing, rotatable stage and base capable of pseudo-darkfield imaging. These two microscopes share a DSLR camera (a Canon EOS Rebel T3i) that can be used interchangeably between the two scopes. The Leech lab also houses a custom Xidax X-8 and an Alienware Aurora R12 "gaming" PC for thermodynamic modeling of complex rocks using Perple_X; these PCs are set up with convenient remote access capability.

Research centers and facilities in the College of Science & Engineering:

• Zeiss Ultra 55 Field emission scanning electron microscope with BSE, STEM detector, Oxford INCA EDS and EBSD, and a 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 preparation 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. We use Channel5 software to process EBSD data.

• Bruker D8 ADVANCE powder x-ray diffractometer

• Raman spectrometer with a 532 nm laser and 50 mW power (in the Department of Physics & Astronomy), and a Horbia Raman system with two laser lines (532 and 788 nm) and a TERS microscope (in the School of Engineering).

• 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)

• The Atomic Force Microscopy Facility

• Gas chromatograph stable isotope analyzer, elemental analyzer, etc. (at the Romberg Tiburon Center for Environmental Studies)

• Glass shop and an electronics repair facility

• The Sierra Nevada Field Campus

Other facilities (in the Bay Area and at other U.S. institutions):

• We also regularly use lab facilities at other universities including collecting mineral composition data on the electron microprobe in the Microchemical Analysis Facility and performing U-Pb zircon geochronology & trace element geochemistry on the Stanford-USGS SHRIMP-RG lab at Stanford University. 

• We send samples to the Peter Hooper GeoAnalytical Lab at Washington State University for whole-rock major and trace element geochemical analyses.

• We have an established relationship with the Noble Gas Lab at the University of Vermont for 40Ar/39Ar geochronology and thermochronology.

• We have collected combined U-Th-Pb geochronologic data and Hf isotope ratios by Laser Ablation ICP Mass Spectrometry (ICP-MS) at the University of Arizona's LaserChron Center. 

Currently offered*

• Global Tectonics (ERTH 795 – graduate level)
• Mineralogy and Petrology I (ERTH 420 – required major course, Spring only)
• Mineralogy and Petrology II (ERTH 520 – major elective, Fall only)
• Our Dynamic Earth (ERTH 112 – GE & required major course)
• Volcanology (ERTH 410 – major elective)

Offered in the past*

• Geochemistry (ERTH 522)
• Physical Geology (ERTH 210)
• Science Partners in K-12 Education (ERTH 652)
• Tectonic Geomorphology (ERTH 795)
• The Violent Earth (ERTH 310)
• Earthquakes and the San Andreas fault
• Geology of the National Parks
• California Rocks!