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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

The LSU Structure / Tectonics research group explores tectonics and the evolution of the continental crust by investigating regional tectonic questions. Our principal tools are field mapping, structural geology, and geochronology; we acquire data via other methods as new research needs arise.

 

Early work has focused on testing and developing models for the construction of the Himalaya, Earth's premier natural laboratory of continent-continent collision. We are furthering this research by investigating the initial collision and shortening (Dennis Donaldson - PhD; Ryan Fox, Ryan Fox, Eric Orphys, Stephen Osborne - undergraduates), emplacement of the range's crystalline core (Dian He, former PhD; Remington Leger and John Craig, former undergraduates; Clayton Campbell, undergraduate), and accommodation of ongoing shortening (Hongjiao Yu, PhD).

 

New research topics include the Mesozoic-Cenozoic crustal evolution in eastern Tibet (Chase Billeaudeau, MS; Suhib Al-Masmoom, Amelia Chia - undergraduates; Michael Stevens, Austin White, John Anthony, Ryan Boucher, former undergraduates), salt tectonics / fold-thrust belt development along the southern Chinese Tien Shan (Cindy Colón, PhD; Kexin Zhang, incoming MS; Ingrid Eckhoff, undergraduate), climatic and anthropogenic impacts on the Mississippi River drainage basin, and the tectonic development of early Earth and hot terrestrial bodies (An Li, PhD).

 

Collaborators include colleagues from LSU, other American institutions, and universities abroad (in Canada, China, England, France, Germany, India, and Nepal).

 

Webb teaches an undergraduate course in Structural Geology, a mixed grad-undergrad course in Plate Tectonics, and a variety of seminars for graduate students. Since 2011, the Plate Tectonics course has been certified as “Communications-Intensive” by LSU’s Communication across the Curriculum program. The course advances students’ visual and technological communication skills via construction of Wikipedia pages in lieu of term papers. For more information about the course, click here; for description of Webb’s use of technology in the classroom, click here.

 

Research Students:

 

PhD:
Cindy Colón
Dennis Donaldson
An Li
Hongjiao Yu

 

MS:
Chase Billeaudeau
Kexin Zhang (incoming Spring 2014)

 

Undergraduate:
Suhib Al-Masmoom
Clayton Campbell
Amelia Chia
Ingrid Eckhoff
Ryan Fox
Eric Orphys
Stephen Osborne

 

Former Graduate Students:
Dian He, PhD 2013, now with Shell Petroleum's Structural Geology specialist group

 

Selected Publications

REFEREED PUBLICATIONS (* indicates student)
 

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., 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.


NON-REFEREED PUBLICATIONS


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

MEETING ABSTRACTS (* indicates student)


Webb, A.G., Moore, W.B., 2013, A new model for early Earth: heat-pipe cooling. AGU Fall Meeting.

Moore, W.B., Webb, A.A.G., 2013, The heat-pipe model of early Earth. GSA Fall Meeting.

Webb, A.A.G., *Yu, H., *He, D., Larson, K., Schmitt, A.K., 2013, The Himalayan mountains and analogous systems were built by underplating. GSA Fall Meeting.

*Donaldson, D.G., Webb, A.G., Menold, C.A., Kylander-Clark, A.R., Hacker, B.R., 2012, Petrochronology of Himalayan UHP eclogite: Implications for the timing of India-Asia collision. AGU Fall Meeting.

*He, D., Webb, A.G., Larson, K.P., Schmitt, A.K., 2012, Was the Himalayan crystalline core emplaced by extrusion or underplating? AGU Fall Meeting.

Webb, A.G., Yin, A., Dubey, C.S., 2012, Origin and assembly of Eastern Himalayan crust: constraints from field mapping and U-Pb zircon geochronology. AGU Fall Meeting.

*Yu, H., Webb, A.G., 2012, Kinematic history of the ongoing growth of Himalayan fold-thrust belt. AGU Fall Meeting.

*He, D., Webb, A.A.G., Larson, K.P., Schmitt, A.K., 2012, New findings from crystalline rocks of the frontal klippen, Nepal Himalaya, demonstrate mountain-building via underplating. 27th Himalaya-Karakoram-Tibet Workshop.

Webb, A.A.G., *He, D., 2012, The South Tibet detachment is a backthrust: new evidence from studies along the length of the Himalayan orogen. 27th Himalaya-Karakoram-Tibet Workshop.

*Yu, H., Webb, A.A.G., 2012, Assembly of the Lesser Himalayan Duplex along the Tons Valley, Northwestern India. 27th Himalaya-Karakoram-Tibet Workshop.

*Habicht, M.H., Menold, C., Webb, A.A.G., *Donaldson, D., 2012, Quantifying paths in UHP terranes: a 3-D approach using thermobarometry and field relationships, GSA Abstracts with Programs.

*Chamberlain, E.L., Webb., A.A.G., *Bergeron, P.G., 2011, Field Apprentice-Instructors: A Means Of Enhancing Graduate And Undergraduate Education In Exercise-Based Geology Field Trips, GSA Abstracts with Programs.

Webb, A.G., *Yu, H., *Hendershott, Z., 2010, Rivers, re-entrants, and 3D variations in orogenic wedge development: a case study of the NW Indian Himalaya, Abstract T51A-2009 presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13-17 Dec.

Webb, A.A.G., Schmitt, A.K., 2010, A new model to resolve the Lesser Himalayan Crystalline Nappe problem: Implications for Himalayan tectonics: Journal of Nepal Geological Society, v.41, p.47.

*Feng, X., Webb, A.A.G., Henry, D.J., 2010, Can Detrital Tourmaline Provide Stratigraphic Fingerprints? Initial Tests in the Western Himalaya, in Leech, M.L., and others, eds., Proceedings for the 25th Himalaya-Karakoram-Tibet Workshop: U.S. Geological Survey, Open-File Report 2010-1099, 2 p. [http://pubs.usgs.gov/of/2010/1099/feng/].

Webb, A.A.G., *Yu, H., 2010, Testing models for the kinematic evolution of the Lesser Himalayan Sequence by balanced reconstruction: Accretion dominant in northwestern India, in Leech, M.L., and others, eds., Proceedings for the 25th Himalaya-Karakoram-Tibet Workshop: U.S. Geological Survey, Open-File Report 2010-1099, 2 p. [http://pubs.usgs.gov/of/2010/1099/webb/].

Webb, A.G., Yin, A., 2009, Structural and lithological discoveries along the strike of the Himalaya change paradigms and possibilities, Eos Trans. AGU, Fall Meet. Suppl., Abstract T43C-2115.

Webb, A.A.G., Schmitt, A.K., 2009, Structural and U-Th-Pb zircon geochronological studies indicate that the central Himalaya developed via tectonic wedging, GSA Abstracts with Programs.

Webb, A.A.G., Yin, A., 2008, Examining the tectonic wedging hypothesis in the NW India Himalaya: Himalayan Journal of Sciences, v. 5 (7), p.168 – Himalaya-Karakorum-Tibet Meeting, Ladakh, India.

Yin, A., Dubey, C.S., Webb, A.A.G., Verma, P.K., Kelty, T.K., Harrison, T.M., 2008, The Central Crystallines around Hapoli, Subansiri, Eastern Himalayas: Himalayan Journal of Sciences, v. 5 (7), p.174-175 – Himalaya-Karakorum-Tibet Meeting, Ladakh, India.

Webb, A.A.G., Yin, A., Harrison, T.M., Célérier, J., Burgess, W.P., Gehrels, G.E., 2006, A New Kinematic Model for the Himalayan Development Based on Along-Strike Variations in Structural Geometry in the NW Indian Himalaya, Eos Trans, AGU, 87(52), Fall Meet. Suppl., Abstract T43E-01.  PDF

Webb, A.A.G., Yin, A., 2006, Structural relationship between the Main Central Thrust and South Tibet Detachment in the NW India Himalaya and its implications for a new model for the Himalayan development: GSA Abstracts with Programs, v. 38, no.7, pp.239.

Webb, A., Yin, A., Harrison, M., Célérier, J., Grove, M., Schmitt, A., Sharma, B., Dubey, C., 2004, Testing models for the emplacement of the Greater Himalayan Crystallines in the NW India Himalaya, paper presented at the Geol. Soc. Lond. meeting: Channel flow, ductile extrusion, and exhumation of lower-mid crust in continental collision zones.

Webb, A., Yin, A., Burnard, P., Blythe, A., 2002, Timing the initiation of extension along the Shanxi Rift, China, with implications for the Cenozoic tectonics of Asia: Eos. Trans. AGU, 83(47), Fall Meet. Suppl., Abstract T61A-1225.

Webb, A., Cheney, J.T., Harms, T.A., Coath, C., 2000, 207Pb / 206Pb in situ ion microprobe dating of monazite from Precambrian metamorphic suites, Tobacco Root Mountains, southwestern Montana: GSA Abstracts with Programs, v. 33, no.1, pp.10.

 

FIELD TRIP GUIDES

 

Webb, A.A.G., Upreti, B.N., 2012, Field Trip Guide: Northwestern Kathmandu Nappe. 27th Himalaya-Karakoram-Tibet Workshop. PDF