"Constraining Structural Complexity in the Sadlerochit Mountains, Northeastern Alaska, from Remote Geologic Mapping and Cross Section Construction"

Shlomo Honig, Honors Thesis 2018

Abstract: The Sadlerochit Mountains are a 65-km long, east-west doubly-plunging, faulted anticline located in northeastern Alaska. These well-exposed mountains represent the northern most surficial exposures of the geology of the Northeast Brooks Range, and as such inform fundamental stratigraphic and structural relationships of exposed Neoproterozoic through Cenozoic strata. In this thesis, we executed an approach that draws on Google Earth's high-resolution satellite imagery and effortless maneuverability of observational scale and perspective in order to compile a remote, low-cost, highly detailed interpretation of formation contacts, faults, and bedding orientations throughout the Sadlerochit Mountains. Using a digital elevation model (DEM) and geologic features we interpreted from Google Earth (i.e. contacts, faults, attitudes), we then constructed a series of cross sections perpendicular to the structural trend of the range. Additionally, by drawing on past work we used the in-house ‘geomapsec' Matlab code to automate cross section construction and thereby demonstrate the efficacy of the otherwise involved process that is cross section construction. Complete with our interpreted formational contacts and attitude measurements from both prior work and from this study's remote extraction of bedding measurements from Google Earth, we used these cross sections to inform the structural evolution of the Sadlerochit Mountains since the Neoproterozoic. To forward model this evolution of observed geologic relationships, we used the in-house fbfFor Matlab code. This code allowed us to manipulate model details such as depositional timing and thicknesses, the timing and character of deformational events, fault shape and slip, rate of subsidence, regional dip, and angular and stratigraphic relationships reflected at the surface of our cross sections. From the work completed in this thesis, we identified key features from our Google Earth remote mapping technique, most notably the presence of laterally extensive thrust faults on the back-limb of the Sadlerochit Mountains and variability in the angular relationships between the Katakturuk Dolomite-Nanook Limestone structural stratigraphic block and the overlying Lisburne Group across the pre-Mississippian Unconformity. Additionally, through this work we were able to improve the efficacy of this workflow, suggest best management practices, and create the opportunity to apply this technique anywhere in the world provided adequate surface exposure that is understudied and difficult or expensive to access.

Full thesis available. Contact the Geology Department at 540-458-8800.