Major research frontiers, grand challenges, and thorny problems in structural geology & tectonics

Surface-deep crust connections

• relationship between deformation processes and structures in the upper crust and those in the lower crust ********
• linking surface and deep deformation to understand the whole lithosphere ********
• nature of vertical coupling throughout the lithosphere ****
• relationship of outcrop-scale structures to lithospheric-scale processes ****
• Establishing the timing of deformational events
• establishing what we are actually dating and with what accuracy and precision ****
• using new tools to obtain PTt paths to learn about the evolution of orogenic belts *
• determining whether transient behavior is represented in the geologic record.

Strain and strain rates

• variations in strain and strain rate across scales, over time, and at different levels in the lithosphere, and what the major factors that lead to these variations, e.g., during construction of an orogen ********
• determining how and why strain (or stress) is partitioned and localized at different times and depths in the crust*****
• quantifying stress, strain, and strain rate at different lithospheric levels *****
• determining how and why some regions are characterized by nonplane, noncoaxial strain and others are marked by "conventional" coaxial plane strain

Geodesy, geodynamics, and structural geology

• correlating geodetic and geologic strain rates, interpreting discrepancies between geologic and geodetic strain rates, and *****
• determining to what extent geodetic measurements help us understand rates and processes in the evolution of fold and fault systems ****
• integrating vertical motions into a 4-D view of plate deformation *
• determining the magnitude of stress in continental lithosphere, driving forces for large-scale crustal extension and shortening

Faults, earthquakes, and structures

• connections between seismological observations and structural mechanisms ****
• partitioning of fault slip between localized and distributed deformation and between interseismic and coseismic deformation ****
• correlation between short term deformation and geologic structures preserved in the rocks ***
• mechanical properties of fault systems at different depths***
• relationship between fault zones, depth, earthquakes, and fluids *
• controls on spectrum of fault slip behavior (creep, slow slip, seismic slip) *

Rheology

• connecting deformation mechanisms with rheology ****
• nature of, controls on, and long-term and transient variations in the rheology and strength of Earth materials **
• coupling of deformation across rheologic transitions **
• 4D rheological model of the lithosphere **
• rheology and strength of middle and lower crust *
• polyphase rheology, importance of water *

Chemistry and deformation

• rates of geochemical reactions and strain ***
• role of fluids, the dynamics of fluids interacting with structures, and fluid chemistry in fabric development, rates of fabric development, and bulk rock deformation ***
• feedbacks between deformation & metamorphism/reaction on various scales *
• the extent to which we can use classical equilibrium thermodynamics to study features formed under non-equilibrium conditions *
• nano-scale processes involved in deformation mechanisms (rock deformation, fluid/rock interactions, chemical reactions)
• effect of chemical reactions on rheology

Climate

• integration of climate, tectonics, landscape evolution, geomorphology, and development of structures to gain a synthetic picture of tectonic settings*
• role of climate in the development of structures