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Mesozoic-Cenozoic structures & stratigraphy record >200 Myr of deformation, uplift, & subsidence in the La Ramada fold-thrust belt, Argentina/Chile (Mackaman-Lofland et al., 2019).
What controls plate coupling, deformation, & uplift/subsidence in Cordilleran mountain belts?
What controls plate coupling, deformation, & uplift/subsidence in Cordilleran mountain belts?
Supported by NSF-EAR-PF 1952791 (2020–2022) & GRFP, GSA, AAPG, & NatGeo student research grants.
Cordilleran (subduction-related) mountain belts are integral to crustal evolution, continental drainage, biological diversity, natural hazard/resource distribution, and other Earth systems. Yet, the construction of Cordilleran orogens has been variably attributed to continuous shortening & crustal thickening, or punctuated (<10−20 Myr) shortening, extension, and/or neutral conditions that may reflect changes in mechanical coupling at the subduction interface.
Our group has addressed this question in the southern central Andes, where deformation involved an apparent shift from continuous shortening to mixed-mode deformation during the Late Cretaceous to Neogene. New research projects focus on the North American Cordillera, where type examples of extensional basin development following construction of the orogen may reflect lithospheric dynamics similar to those controlling mixed-mode deformation in the Andes.
Links to related publications: Mackaman-Lofland et al., JSAES (2019); Mackaman-Lofland et al., EPSL (2024)
Aerial view of the North American fold-thrust belt (Montana-southern Canada) and adjacent foreland basin system.
How is thrust belt activity or quiescence recorded in adjacent foreland basins?
How is thrust belt activity or quiescence recorded in adjacent foreland basins?
Supported by NSF-EAR 2419297 (2024–2027)
Documenting the growth of fold-thrust belts is fundamental to understanding continental deformation and the growth of high topography. While foreland basins provide valuable archives of thrust belt evolution that often extend back to the early history of an orogen, debate persists regarding intervals of thrust belt propagation or quiescence, delivery of coarse clastic deposits to the distal foreland, & development of foreland basin unconformities.
A new research direction combines geo-/thermochronologic constraints from the Canadian fold-thrust belt and foreland basin with flexural, kinematic, & thermal history modeling techniques to quantitatively evaluate the relationships among deformation, erosion, uplift/subsidence, & sedimentation and advance understanding of how the foreland basin recorded active shortening vs. quiescent events.
We are actively recruiting a UTK graduate student to contribute to this project starting Summer or Fall 2025. Research will involve fieldwork, cross section construction/validation, and kinematic, flexural, & thermal history modeling.
Map of major sedimentary cover- & crystalline basement-involved faults near Mendoza and San Juan, Argentina. Focal mechanisms are shown for historically significant earthquakes at shallow (black) or mid-crustal (blue) depths (Ammirati et al., 2022).
To what extent are upper-crustal faults linked to lower-crustal & deep Earth systems?
To what extent are upper-crustal faults linked to lower-crustal & deep Earth systems?
Supported by NSF-EAR 2445472 (2023–2026)
Understanding the behavior of faults and fault-like structures through the full thickness of the lithosphere remains an outstanding challenge, with implications for seismic hazard assessment in tectonically active regions. Ongoing research integrates structural, basin, & geophysical analyses with thermochronology data and flexural thermokinematic modeling to resolve enigmatic basement fault geometries and understand their influence on historically damaging seismicity near Mendoza & San Juan, Argentina.
We are actively recruiting a UTK graduate student to contribute to this project starting Spring or Fall 2025. Research will involve fieldwork, geo-/thermochronology analyses, & cross section construction/validation using flexural thermokinematic modeling.
Kishenehn Basin & Lewis thrust sheet, NW Montana. The persistence of high-elevation & -relief topography >10 Myr after the initiation of normal faulting in this region (Fan et al., 2017; 2021) may indicate uplift driven by deeper processes during orogenic collapse.
Testing geodynamic & climatic hypotheses using kinematic and thermal history models
Testing geodynamic & climatic hypotheses using kinematic and thermal history models
Advances in paleoaltimetry and geo/thermochronology enable the direct dating of topographic uplift, rock exhumation, and sedimentation events, and allow us to explore how changing thermal and isotopic signals reflect upper-crustal processes, climate, and/or mantle dynamics through time. New flexural, kinematic, and thermal history modeling techniques further harness spatial patterns in these data to inform interpretations of fault geometries, deformation kinematics, and signals of dynamic uplift/subsidence in diverse environments.
Ongoing goals include (1) leveraging flexural thermokinematic modeling to discern the Earth surface response to lower-crustal & mantle dynamics; and (2) creating resources to train more researchers in the use of these modeling tools, which are transferrable to diverse questions & geologic settings.
Links to related publications: Mackaman-Lofland et al., Tectonics (2022); Mackaman-Lofland et al., EPSL (2024)
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