ADL Alexander Dmitri Lusk
Postdoctoral researcher at the University of Wisconsin - Madison

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Research Interests
My current research investigates the mechanics of lithospheric deformation and the evolution of plate boundary-scale shear zones and associated orogens. Although significant progress has been made towards understanding how the lithosphere deforms at and below the drittle to ductile transition, significant uncertainty remains in how we model the structure and geometry of large-scale shear zones and by what mechanisms strain localizes from broad zones of distributed strain to discrete high-strain surfaces.

I employ a multidisciplinary approach, integrating detailed fieldwork, mapping, optical and electron microscopy, quantitative petrology and thermobarometry, structural and mechanical analysis of deformed terranes, geochronology, experimental rock deformation, and numerical, petrological, and geophysical modeling to better address these questions from multiple perspectives and scales.

Contact me if you have any questions or are interested in collaborating!

Click on locations for more details!
Research_Areas Ruby Mountains NW Argentina

Upper mantle deformation and rheology

Coming soon!


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Deep structure of the Scandian thrust zone, NW Scotland

This project focuses on better understanding the deep structure, geometry, and mechanisms accommodating strain localization in lithosphere-scale fault zones, especially at and below the frictional to viscous transition. One of the primary goals is to constrain the rheology and internal structure of these zones in reconstructed depth and time. To achieve this, we perform detailed fieldwork and microstructural analysis along several transects across the Moine thrust zone, NW Scotland. Rocks along these transects preserve microstructures representative of different stages in shear zone evolution (see figure below), which allows us to identify spatial and temporal changes in rock microstructure, deformation conditions, deformation mechanisms, paleo-stress, and paleo-strain rate to put constraints on rock rheology during deformation. This work was published in a Lithosphere paper (Lusk and Platt, 2020).

In addition, to better understand the geometry and orientation of these large-scale structures at depth, we are using gravity modeling to construct plausible geophysically-constrained cross sections across NW Scotland.

Initial results for this project have been presented at AGU and other conferences. Two additional manuscripts are in preparation.



Reconciling experimental and natural deformation: a naturally-calibrated flow law for quartz

As part of this project I am using existing experimental data in conjunction with naturally deformed rocks from the Scandian thrust zone to calculate constitutive parameters for dislocation creep in wet quartz rocks. This work has been presented at AGU and the Rock Deformation Gordon Research Conference. A manuscript is currently in review.


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Shear zones in the Famatinian orogen, NW Argentina

The Sierras Pampeanas and surrounding areas in NW Argentina expose complete crustal sections of the Ordovician Famatinian orogen from the top of the arc to mid- to lower-crustal shear zones. This work is a collaborative effort with researchers at the CRILAR Institute to better understand how orogens form and strain localizes at different levels within the lithosphere. To achieve this, we construct detailed geological maps and analyze how rocks deform from the micro- to orogen-scale to reconstruct and better understand the spatial and temporal history of orogenesis and strain localization through the lithosphere.

Results from these projects have been presented at GSA, EGU, and other local conferences. A manuscript was recently accepted to the Journal of South American Earth Sciences (Lusk et al., 2020)


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Strain localization at the micro-scale: quantifying shear zone microstructure in Joshua Tree National Park

Small cm- m-scale mylonitic to ultramylonitic shear zones deform otherwise pristine Jurassic plutons in Joshua Tree National Park. This project has three primary goals:

1. Investigate the degree to which crystal plastic deformation affects trace element concentration and distribution in naturally-deformed quartz. We are using cathodoluminescence, secondary ion mass spectrometry, and electron backscatter diffraction to quantify the relationship between trace element concentration and quartz microstructure from the single grain to shear zone scale.

2. Examine mechanisms that localize strain at the micro-scale.

3. Characterize Jurassic deformation in the Mojave region.



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Shuswap Metamorphic Core Complex, British Columbia

Coming soon!

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Last updated 8/2020
All contents copyright (c) 2015-2020 Alexander Lusk