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A. Alexander  G.  Webb 
Associate Professor
Bachelor's Degree(s): Amherst College, 2001
PhD: University of California at Los Angeles, 2007
PostDoc: University of California at Los Angeles, 2008
Phone: (225) 578-5810
Fax: (225) 578-2302
Office: E303B Howe-Russell Building

Area of Interest

RESEARCH INTERESTS
I explore tectonic processes and their interactions with other planetary systems. Early work focused on testing and developing models for the construction of the Himalaya, Earth's premier natural laboratory of continent-continent collision. Continuing Himalayan research includes investigations of (i) initial collision and shortening, (ii) development of the range's crystalline core, and (iii) modes of ongoing shortening. I am now pursuing a new research focus – tectonics of early Earth and development of hot terrestrial planets – for which the kinematics of rapid volcanic resurfacing appears to be a major, underappreciated control on long-term evolution. Other ongoing projects explore (a) salt tectonics and surface processes along the southern Chinese Tian Shan and (b) tectonic, climatic, and anthropogenic impacts on the Mississippi River delta.

 

RESEARCH APPROACH
I use geologic mapping integrated with analytical research to dissect the architecture and evolution of complex tectonic systems. Principal analytical tools are geo-/thermo-chronology and balanced palinspastic reconstruction, by which I determine timing, rates, and magnitudes of deformation. As my range of interests expands, I am increasingly pursuing collaborative research employing a range of techniques (e.g., geochemistry, geodesy, numerical modeling, petrology, remote sensing, sedimentology).

 

TEACHING
My teaching for undergraduate, graduate, and mixed student populations includes courses in Structural Geology, Plate Tectonics, Field Geology, and Evolution of the Terrestrial Planets. Since 2011, the Plate Tectonics course has been certified as “Communications-Intensive” by LSU’s Communication across the Curriculum program; the Terrestrial Planets course (first taught in 2014) is similarly certified. These courses advance students’ visual and technological communication skills via construction of Wikipedia pages in lieu of term papers. For more information about the Spring 2015 Terrestrial Planets course, click here, for more information about the Fall 2014 Plate Tectonics course and its completed pages, click here

Selected Publications

Myrow, P.M., Hughes, N.C., Derry, L.A., McKenzie, N.R., Jiang, G., Webb, A.A.G., Banerjee, D.M., Paulson, T.S., Singh, B.P., Timing of onset of uplift of the Lesser Himalaya: Implications for tectonic models of Cenozoic deformation. EPSL, in press.

 

Yu, H., Webb, A.A.G., He, D., Extrusion vs. duplexing models of Himalayan mountain building 1: Discovery of the Pabbar thrust confirms duplex-dominated growth of the northwestern Indian Himalaya since Mid-Miocene. Tectonics, in press. 

 

He, D., Webb, A.A.G., Larson, K.P., Martin, A.J., Schmitt, A.K., 2015, Extrusion vs. duplexing models of Himalayan mountain building 3: Duplexing dominates from Oligocene to present. International Geology Review, v. 57, p. 1-27. PDF

 

Li, J., Webb, A.A.G., Mao, X., Eckhoff, I., Colón, C., Zhang, K., Wang, H., Li, A., He, D., 2014, Active surface salt structures of the western Kuqa fold-thrust belt, northwestern China. Geosphere, v. 10, no. 6, p. 1219-1234. PDF

 

Moore, W.B., Webb, A.A.G., 2013, Heat-pipe Earth. Nature, v. 501, p. 501-505.

http://www.nature.com/nature/journal/v501/n7468/full/nature12473.html

 

Bader, T., Franz, L., Ratschbacher, L., de Capitani, C., Webb, A.A.G., Yang, Z., Pfänder, J.A., Hofmann, M., Linnemann, U., 2013, The heart of China revisited: II Early Paleozoic (ultra)high-pressure and (ultra)high-temperature metamorphic Qinling orogenic collage. Tectonics, v. 32, p. 922-947. PDF

 

*Leger, R.M., Webb, A.A.G., Henry, D.J., *Craig, J.A., Dubey, P., 2013, Metamorphic field gradients across the Himachal Himalaya, northwest India: Implications for the emplacement of the Himalayan crystalline core. Tectonics, v. 32, p. 540-557. PDF  

(e-mail Dr. Webb for supplementary material file)

 

*Donaldson, D.G., Webb, A.A.G., Menold, C.A., Kylander-Clark, A.R.C., Hacker, B.R., 2013, Petrochronology of Himalayan ultrahigh-pressure eclogite. Geology, v. 41, p. 835-838. PDF  SUPPLEMENT

 

Webb, A.A.G., 2013, Preliminary palinspastic reconstruction of Cenozoic deformation across the Himachal Himalaya (northwestern India). Geosphere. v. 9, p. 572-587. PDF  PLATE

 

Webb, A.A.G., Yin, A., Dubey, C.S., 2013, U-Pb zircon geochronology of major lithologic units in the Eastern Himalaya: Implications for the origin and assembly of Himalayan rocks. Geological Society of America Bulletin. v. 125, p. 499-522. PDF


Schmidt, J., Hacker, B.R., Ratschbacher, L., Stübner, K., Stearns, M., Kylander-Clark, A., Cottle, J.M., Webb, A.A.G., Gehrels, G., Minaev, V., 2011, Cenozoic Deep Crust in the Pamir. Earth and Planetary Science Letters. v. 312, p. 411-421. PDF
 

Webb, A.A.G., Yin, A., Harrison, T.M., Célérier, J., Gehrels, G.E., Manning, C.E., Grove, M., 2011, Cenozoic tectonic history of the Himachal Himalaya (northwestern India) and its constraints on the formation mechanism of the Himalayan orogen. Geosphere. v. 7, p. 1013-1061.  

(e-mail Dr. Webb for full file)


Webb, A.A.G., Schmitt, A.K., *He, D., Weigand, E.L., 2011, Structural and geochronological evidence for the leading edge of the Greater Himalayan Crystalline complex in the central Nepal Himalaya. Earth and Planetary Science Letters. v. 304, p. 483-495. PDF  

(e-mail Dr. Webb for supplementary material file)

Yin, A., Dubey, C.S., Kelty, T.K., Webb, A.A.G., Harrison, T.M., Chou, C.Y., Célérier, J., 2010, Geological correlation of the Himalayan orogen and Indian craton: Part 2. Structural geology, geochronology, and tectonic evolution of the Eastern Himalaya. Geological Society of America Bulletin. v. 122, p. 360-395. PDF


Yin, A., Dubey, C.S., Webb, A.A.G., Kelty, T.K., Grove, M., Gehrels, G.E., Burgess, W.P., 2010, Geological correlation of the Himalayan orogen and Indian craton: Part 1. Structural geology, U-Pb zircon geochronology, and tectonic evolution of the Shillong Plateau and its neighboring regions in NE India. Geological Society of America Bulletin. v. 122, p. 336-359.  PDF


Célérier, J., Harrison, T.M., Beyssac, O., Herman, F., Dunlap, W.J., Webb, A.A.G., 2009, The Kumaun and Garwhal Lesser Himalaya, India: Part 2. Thermal and deformation histories. Geological Society of America Bulletin. v. 121, p. 1281-1297.  PDF


Célérier, J., Harrison, T.M., Webb, A.A.G., Yin, A., 2009, The Kumaun and Garwhal Lesser Himalaya, India: Part 1. Structure and stratigraphy. Geological Society of America Bulletin, v. 121, p. 1262-1280. PDF


 

Webb, A.A.G., Yin, A., Harrison, T.M., Célérier, J., Burgess, W.P., 2009, The leading edge of the Greater Himalayan Crystallines revealed in the NW Indian Himalaya: Implications for the Evolution of the Himalayan Orogen: Geology, v.37 (2), e189-190, REPLY to A.K. Dubey. PDF

 

Webb, A.A.G., Yin, A., Harrison, T.M., Célérier, J., Burgess, W.P., 2007, The leading edge of the Greater Himalayan Crystallines revealed in the NW Indian Himalaya: Implications for the Evolution of the Himalayan Orogen: Geology, v.35 (10), p.955-958. PDF

(e-mail Dr. Webb for data repository file file)


Cheney, J.T., Webb, A.A.G., Coath, C.D., McKeegan, K.D., 2004, In situ ion microprobe 207Pb/206Pb dating of monazite from Precambrian metamorphic suites, Tobacco Root Mountains, Montana, in GSA Special Paper 377, p. 151-179.

Other

STUDENT ADVISING

Current Graduate Advisees (6):
Cindy Colón (PhD – 4th year)
Dennis Donaldson (PhD – 6th year)
Hongcheng Guo (MS – 1st year)
Andrew Webb (MS – 1st year) (no relation)
Kexin Zhang (MS – 2nd year)
Jiawei Zou (MS – 1st year)

 

Current Undergraduate Advisees (9):
Spencer Aertker, Patrick Baudoin, Anne Brennan, Erinn Buhyoff, Ross Harrison, Shelby Johnson, Danielle LeBlanc, Garrett Nielson, Madeline Stoltz

 

Graduate Degrees Awarded (3):
Dian He (PhD 2013; now at Shell Structural Geology Specialist Group, Houston, Texas)
Hongjiao Yu (PhD 2014; Houston, Texas)
Chase Billeaudeau (MS 2014; Lafayette, Louisiana)