About

William (Will) Lamb is a professor in the Department of Geology & Geophysics at Texas A&M University. His research focuses on metamorphic petrology and geochemistry, specifically the characterization of metamorphism in the earth's crust and mantle, including the study of temperatures, pressures, and fluid compositions and movements. His work involves fieldwork, petrography, microprobe analyses, phase equilibria, fluid inclusions analyses (both natural and synthetic), and stable isotopic analyses. He earned his Ph.D. from the University of Wisconsin in 1987. His contributions include applying mineral equilibria to estimate fugacities of H2O, H2, and O2 in mantle xenoliths, studying coupled deformation and melt-migration events related to subduction initiation, and investigating water and oxygen fugacity in the lithospheric mantle wedge beneath the Northern Canadian Cordillera. His research provides insights into the processes occurring within the Earth's crust and mantle, advancing understanding of metamorphic and geochemical phenomena.

Research topics

• Geology
• Geochemistry
• Seismology
• Materials science
• Petrology
• Geophysics
• Chemistry
• Ecology
• Oceanography
• Composite material
• Biology
• Mineralogy
• Paleontology

Selected publications

• Estimating Values of Fe3+/Σfe In Pyroxenes with the Electron Microprobe

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

• Fluids in the shallow mantle of southeastern Australia: Insights from phase equilibria

  American Mineralogist · 2024-03-28

  article1st authorCorresponding

  Abstract Small amounts of water (tens to hundreds of parts per million) can have a profound effect on the properties of mantle peridotites, including viscosities, conductivities, and melting temperatures. Measuring the water content of nominally anhydrous minerals (NAMs) has provided insight into the amounts of water contained within mantle rocks. However, converting from NAM water contents to the activity of H2O is non-trivial. Equilibria involving amphibole can be used to determine values of the activity of H2O (aH2O) at the time of mineral equilibration. This approach yields low values of the activity of H2O (<0.3) for four peridotite xenoliths from Southeastern Australia. These four xenoliths also record values of oxygen fugacity (fO2) that range from –0.2 to –1.2 log units below the fayalitemagnetite-quartz buffer. All these values of fO2 are inconsistent with the presence of a CH4-rich fluid (too oxidizing), and the lowest value of oxygen fugacity, as recorded by one sample, is inconsistent with the presence of a CO2-rich fluid.

  PublisherDOI

• Estimating values of Fe3+/ΣFe in pyroxenes with the electron microprobe

  Lithos · 2024-08-08

  article1st authorCorresponding
  PublisherDOI

• A marine origin of coal balls in the Midland and Illinois basins, USA

  Communications Earth & Environment · 2023 · 2 citations

  • Geology
  • Paleontology
  • Geochemistry

  Abstract Coal balls are carbonate concretions that preserve peat in cellular detail. Despite their importance to paleobotany, the salinity of coal-ball peat remains controversial. Pennsylvanian coal balls from the Midland and Illinois basins contain echinoderms and early high-magnesium calcite cement. Echinoderm skeletons reflect the Mg/Ca ratio of the seawater in which they grew. Here we show that well-preserved echinoderms in coal balls and North American Pennsylvanian marine facies have similar average mole % MgCO 3 ; 10.2–12.3 and 9.9–12.5 respectively. Coal-ball echinoderms reflect the magnesium content of the adjacent epicontinental seawater. Early high-magnesium calcite cement in coal balls has the same, or more magnesium than echinoderms from the same deposit, and high Sr/Ca and Na/Ca, consistent with formation in marine or brackish water. Subsequent coal-ball cement is low-magnesium calcite, suggesting freshwater diagenesis and cementation followed formation of marine high-magnesium calcite. Coal balls likely formed in the marine-freshwater mixing zone.

  PublisherOA PDFDOI

• Carbonates and Intermediate-Depth Seismicity: Stable and Unstable Shear in Altered Subducting Plates and Overlying Mantle

  Zenodo (CERN European Organization for Nuclear Research) · 2023-04-20

  datasetOpen accessSenior author

  Prakash et al (2023) - "Carbonates and Intermediate-Depth Seismicity: Stable and Unstable Shear in Altered Subducting Plates and Overlying Mantle" This repository contains:<br> -data exported from shear heating instability model shown in figures 2, 3, 4, S4, S5, and S6<br> -matlab code used to plot figures For further information, please contact Abhishek Prakash (abhishek.prakash@tamu.edu).

  PublisherDOI

• Carbonates and Intermediate-Depth Seismicity: Stable and Unstable Shear in Altered Subducting Plates and Overlying Mantle

  Zenodo (CERN European Organization for Nuclear Research) · 2023-04-20

  datasetOpen accessSenior author

  Prakash et al (2023) - "Carbonates and Intermediate-Depth Seismicity: Stable and Unstable Shear in Altered Subducting Plates and Overlying Mantle" This repository contains:<br> -data exported from shear heating instability model shown in figures 2, 3, 4, S4, S5, and S6<br> -matlab code used to plot figures For further information, please contact Abhishek Prakash (abhishek.prakash@tamu.edu).

  PublisherDOI

• Mg/Ca and Sr/Ca ratios of Echinoderm ossicles and plants from Late Pennsylvanian Coal Balls of the Midland (Dalton coal) and Illinois basins (Calhoun Coal), North America

  Figshare · 2023-01-01

  datasetOpen access

  Data Sheet 1. Dalton and Calhoun high-magnesium calcite (HMC) results. Magnesium and calcium contents for echinoderms and coal ball calcite. Seawater Mg/Ca_SW mol/mol calculated using partition coefficient <em>D</em>_<em>C</em>Mg = 0.03757 (Dickson, 2004) and power partition functions Mg/Ca_C = 0.0516Mg/Ca_SW0.668, Mg/Ca_C = 0.0482Mg/Ca_SW0.898 (Ries, 2004). Sr/Ca and Na/Ca ratios reported in mmol/mol. Data Sheet 2. Dalton and Calhoun low-magnesium calcite (LMC) results. Mg and Ca contents for echinoderms and coal ball calcite. Sr/Ca and Na/Ca ratios reported in mmol/mol. Chemical characterization of carbonates by wave-length dispersive (WDS) analyses with a Cameca SX-5, housed in the Texas A&amp;M Materials Characterization Facility (RRID:SCR_022202). Calcium, Magnesium, Strontium, Iron, Sodium, Manganese, Sulfur, Silicon and Aluminum contents of echinoderm ossicles and plant cements analysed.

  PublisherDOI

• Carbonates and intermediate-depth seismicity: Stable and unstable shear in altered subducting plates and overlying mantle

  Proceedings of the National Academy of Sciences · 2023 · 14 citations

  Senior authorCorresponding
  • Geology
  • Geochemistry
  • Petrology

  O-saturated olivine. However, magnesian carbonates may extend to greater mantle depths than hydrous silicates at temperatures and pressures of subduction zones. Strain rates within altered downgoing mantle peridotites may be localized within carbonated layers following slab dehydration. A simple model of shear heating and temperature-sensitive creep of carbonate horizons, based on experimentally determined creep laws, predicts conditions of stable and unstable shear with strain rates up to 10/s, comparable to seismic velocities of frictional fault surfaces. Applied to intermediate-depth earthquakes of the Tonga subduction zone and the double Wadati-Benioff zone of NE Japan, this mechanism provides an alternative to the generation of earthquakes by dehydration embrittlement, beyond the stability of antigorite serpentine in subduction zones.

  PublisherOA PDFDOI

• Strain Localization at Constant Strain Rate and Changing Stress Conditions: Implications for Plate Boundary Processes in the Upper Mantle

  Minerals · 2021 · 7 citations

  • Geology
  • Petrology
  • Geophysics

  We present results from a natural deformed shear zone in the Turon de Técouère massif of the French Pyrenees that directly addresses the processes involved in strain localization, a topic that has been investigated for the last 40 years by structural geologists. Paleopiezometry indicates that differential stresses are variable both spatially across the zone, and temporally during exhumation. We have, however, also calculated strain rate, which remains constant despite changes in stress. This result appears to be at odds with recent experimental deformation on monophase (olivine) rocks, which indicate that strain localization occurs dominantly as a result of constant stress. We hypothesize that in the Turon de Técouère massif—and many natural shear zones—strain localization occurs as a result of reactions, which decrease the grain size and promote the activation of grain size sensitive deformation mechanisms. From a tectonics perspective, this study indicates that the deformation rate in a particular plate boundary is relatively uniform. Stress, however, varies to accommodate this deformation. This viewpoint is consistent with deformation at a plate boundary, but it is not the typical way in which we interpret strain localization.

  PublisherOA PDFDOI

• Stable and Unstable Shear in Altered Downgoing Slabs: Predicted Strain Localization in Magnesian Carbonates and Wadati-Benioff Seismicity

  2020-03-09

  articleOpen access

  &amp;lt;p&amp;gt;Seismicity of subduction zones at upper-mantle depths is commonly explained by dehydration reactions of serpentine and hydrous silicates and reductions in effective pressure. However, the conditions of Wadati-Benioff zone seismicity do not strictly correspond to temperatures and depths of serpentine dehydration, and there is no independent evidence that seawater penetrates the lithosphere to form serpentine at depths &amp;gt;30km below the seafloor. Altered lithosphere may contain magnesian carbonates in addition to hydrous silicates, both at the top of plates, where CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; of seawater reacts with mantle rocks and at the base of plates where CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; is introduced by mantle plumes.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Adapting the thermal softening model of Kelemen and Hirth (2007), we model the strain localization and shear heating within magnesite horizons embedded within an olivine host using flow laws determined experimentally for dislocation creep and diffusion creep of the carbonate layer and olivine host (Hirth and Kohlstedt, 2003; Holyoke et al., 2014). Strain rates predicted within carbonate-rich layers of downgoing slabs are much higher than those of the surrounding olivine at all conditions. However, shearing may be either stable or unstable depending on the relative rates of shear heating and conductive heat loss from the shear zone. Localized strain rates reach a steady state when shear heating and heat flow are balanced, while unstable strain rates are calculated where shear heating exceeds heat flow. Modeled strain rates accelerate to 10&amp;lt;sup&amp;gt;+1 &amp;lt;/sup&amp;gt;s&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;, as temperatures reach melting conditions, and stresses drop, corresponding to a seismic event. Applications of this model to the double Benioff zones of the NE Japan trench predict unstable seismic shear for both upper and lower seismic zones to subduction depths of ~300 km. For cold downgoing slabs, such as the Tonga subduction system, unstable seismic shear is predicted for carbonate horizons of altered downgoing slabs to depths exceeding 400 km.&amp;lt;/p&amp;gt;

  PublisherDOI

Frequent coauthors

• Robert Popp

  13 shared

• Lindsey E. Hunt

  University of Oklahoma

  9 shared

• P. B. Kelemen

  8 shared

• John W. Valley

  University of Wisconsin–Madison

  8 shared

• A. K. Kronenberg

  Texas A&M University

  7 shared

• Basil Tikoff

  University of Wisconsin–Madison

  7 shared

• S. H. Kirby

  6 shared

• C. W. Holyoke

  University of Akron

  6 shared

Education

• Ph.D., Geology & Geophysics

  University of Wisconsin Madison

  1987