Geologic Mapping in the 21st Century

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PhD candidate studying the interplay of modern technology and traditional field techniques.

PINBOARD SUMMARY

Increased computing power has led to a future of geologic mapping done digitally.

In ten seconds? Modern geologic mapping has been transformed from paper based to a digital interface. This is an ongoing transition driven by increasing computing power and dissemination of high resolution imagery.

Don't believe it? Digital globes, for example Google Earth, are now commonplace for either pre- or post-field assessment of a study area. Research is also being done to assess the capabilities of smartphones in recording geologic data.

Are the "traditional" methods still useful? Yes, many research questions are still being investigated using traditional paper mapping. In addition, the precision of smartphone in recording orientation data is still catching up to that of a compass.

So technology has changed how geologic research is done?

Yes, it's created new data products... - UAVs have allowed for the routine dissemination of 3D outcrop models. Old data is now being digitized via the creation of digital maps from legacy maps thanks to the efficiency of modern computers. Increased computing power has also allowed for the development of 3D geologic models, which incorporate many datasets (e.g. seismic, DEMs, mapping, etc.), to become a regular practice.

...increased workflow efficiency - Modern applications of satellite imagery gives researcher the ability to conduct coarse geologic mapping before entering the field in order to better economize time. While in the field, mapping is increasingly being done via electronic tablets and with electronic compasses. This removes steps of digitizing paper maps as well as allowing for variable scaling and overlays in the field as opposed to carrying alternative paper maps.

Where do we go from here? - The goals for future technology integration should center on efficient dissemination of 3D data products. Also, as consumer technology increases in reliability the errors associated with models and data collection will decrease.

11 ITEMS PINNED

Geosciences, Vol. 6, Pages 32: Three-Dimensional Geological Model of Quaternary Sediments in Walworth County, Wisconsin, USA

Abstract: A three-dimensional (3D) geologic model was developed for Quaternary deposits in southern Walworth County, WI using Petrel, a software package primarily designed for use in the energy industry. The purpose of this research was to better delineate and characterize the shallow glacial deposits, which include multiple shallow sand and gravel aquifers. The 3D model of Walworth County was constructed using datasets such as the U.S. Geological Survey 30 m digital elevation model (DEM) of land surface, published maps of the regional surficial geology and bedrock topography, and a database of water-well records. Using 3D visualization and interpretation tools, more than 1400 lithostratigraphic picks were efficiently interpreted amongst 725 well records. The final 3D geologic model consisted of six Quaternary lithostratigraphic units and a bedrock horizon as the model base. The Quaternary units include in stratigraphic order from youngest to oldest: the New Berlin Member of the Holy Hill Formation, the Tiskilwa Member of the Zenda Formation, a Sub-Tiskilwa Sand/Gravel unit, the Walworth Formation, a Sub-Walworth Sand/Gravel unit, and a Pre-Illinoisan unit. Compared to previous studies, the results of this study indicate a more detailed distribution, thickness, and interconnectivity between shallow sand and gravel aquifers and their connectivity to shallow bedrock aquifers. This study can also help understand uncertainty within previous local groundwater-flow modeling studies and improve future studies.

Pub.: 11 Jul '16, Pinned: 06 May '17

2D to 3D geologic mapping transformation using virtual globes and flight simulators and their applications in the analysis of geodiversity in natural areas

Abstract: This work describes the transformation process from 2D cartography to 3D, simply by overlapping images in common formats (jpeg, bmp, tiff, png, etc.) on Google Earth’s virtual globe. Arribes del Duero Natural Park, located west of the province of Salamanca, Spain, was the object of this part of the study. Other natural areas are also discussed and were used to establish a procedure for mapping geodiversity and for identifying areas of geological uniqueness and naturalness within the natural areas. To do this, different parametric indices were used to empirically generate different degrees of geological diversity in the Quilamas Natural Area, located south of Salamanca, Spain. Intermediate parametric maps were processed using two types of GIS technical: graphical (neighbourhood operations) and alphanumeric (calculated from the fields in the attribute table). Intermediate parametric maps were processed using two types of technical GIS: neighbourhood operations (graphics) and alphanumeric (calculated from the fields in the attribute table). These maps were used to establish areas with the greatest concentration of geological diversity elements and to define areas with a greater need for protection when planning the management of human activities in natural areas. Finally, the flight simulator tool, which was implemented in the free virtual globe and controlled using a keyboard or joystick, allows you to “fly” through the projected geological mapping of Arribes Del Duero Natural Park or view the parametric mapping and geodiversity in the newly created Quilamas Natural Area. Interoperability with the Google Maps application allows you to identify and observe the outcrops of the various geological materials in natural or anthropic terrain cuts.

Pub.: 20 Dec '14, Pinned: 06 May '17

Application of ASTER remote sensing data to geological mapping of basement domains in arid regions: a case study from the Central Anti-Atlas, Iguerda inlier, Morocco

Abstract: Satellite remote sensing is shown to provide critical support for geological and structural mapping in semiarid and arid areas. In this work, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were used to clarify the geological framework of the Precambrian basement of the Iguerda Proterozoic inlier in the Moroccan Central Anti-Atlas. In this study, the interpretation of the processed digital data has been ground truthed with geological field data collected during a reconnaissance-mapping program in the Central Anti-Atlas. The Iguerda inlier offers a deeply eroded Precambrian massif dominated by a Paleoproterozoic basement composed of supracrustal metasedimentary units intruded by various Eburnian granitoids. Impressive mafic dyke swarms mainly of Proterozoic age crosscut this basement. Eburnian basement rocks are unconformably overlain by Lower Ediacaran volcanosedimentary rocks of the Ouarzazate Group and Upper Ediacaran–Lower Cambrian carbonates. The applied ASTER analyses are particularly effective in the lithological differentiation and discrimination of geological units of the Iguerda inlier. The spectral information divergence (SID) classification algorithm coupled with spectral angle mapper and maximum likelihood classification effectively discriminates between metamorphic rocks, granitoid bodies, and carbonate cover. SID classification improves geologic map accuracy with respect to the spatial distribution of plutonic bodies and metamorphic units. In addition, Paleoproterozoic granitoids have been well discriminated into separate distinct suites of porphyritic granites, granodiorites, and peraluminous leucogranite suites. This discrimination was initially identified via remote sensing analysis and later ground truthed in the field. This methodology enhances geological mapping and illustrates the potential of ASTER data to serve as a vital tool in detailed geologic mapping and exploration of well-exposed basement of arid regions, such as the Proterozoic of the Anti-Atlas Mountains of Morocco.

Pub.: 16 May '13, Pinned: 04 May '17

Using unmanned aerial vehicles and structure-from-motion photogrammetry to characterize sedimentary outcrops: An example from the Morrison Formation, Utah, USA

Abstract: Recently developed data collection techniques allow for improved characterization of sedimentary outcrops. Here, we outline a workflow that utilizes unmanned aerial vehicles (UAV) and structure-from-motion (SfM) photogrammetry to produce sub-meter-scale outcrop reconstructions in 3-D. SfM photogrammetry uses multiple overlapping images and an image-based terrain extraction algorithm to reconstruct the location of individual points from the photographs in 3-D space. The results of this technique can be used to construct point clouds, orthomosaics, and digital surface models that can be imported into GIS and related software for further study. The accuracy of the reconstructed outcrops, with respect to an absolute framework, is improved with geotagged images or independently gathered ground control points, and the internal accuracy of 3-D reconstructions is sufficient for sub-meter scale measurements. We demonstrate this approach with a case study from central Utah, USA, where UAV-SfM data can help delineate complex features within Jurassic fluvial sandstones.

Pub.: 31 Mar '17, Pinned: 04 May '17

Assessment of the precision of smart phones and tablets for measurement of planar orientations: A case study

Abstract: Although paper and pencil approaches to geological mapping continue, digital mapping tools are being increasing implemented in field geology. Of particular note is the use of an electronic compass/inclinometer built into tablets and smartphones for obtaining orientation data where an important question is the reliability of these digital devices relative to conventional, analogue compass/inclinometers. This paper deals with this question through detailed tests of two android devices: an Honor 3C smartphone and a Lenovo B8080-F tablet. In order to evaluate potential electronic noise effects the devices were tested in two modes, standard and airplane. Over 14,000 readings from the sensors were collected to evaluate the stability of the sensor's readings and showed that the magnetic sensor in the tablet was unacceptably unstable. Seven geological compass applications were installed on the Honor 3C smartphone and tested against the analogue Freiberg geological compass in a field experiment. During the experiment 25 fractures varying in azimuth and dip were measured using both devices. A high level of disagreement was observed with discrepancies as high as 80° with azimuthal errors dominant. Analysis of the time series in the data suggest the source of the problem was instability in the magnetic sensor for the smartphone, despite the fact the device passed the initial stability test. Although only two devices were studied these data indicate care must be taken to evaluate compass accuracy on these devices.

Pub.: 27 Feb '17, Pinned: 04 May '17

Digital soil mapping of sand content in arid western India through geostatistical approaches

Abstract: Digital maps of sand content of arid western India were prepared using legacy soil data published by National Bureau of Soil Survey and Land Use Planning, Nagpur following digital soil mapping (DSM) approach. In the first step, profile data was harmonized to standard depths as followed by GlobalSoilMapping programme e.g. 0–5 cm, 5–15 cm, 15–30 cm, 30–60 cm, 60–100 cm and 100–200 cm using mass preserving spline tool in R. Four different approaches of DSM methodology were applied to prepare sand content map of arid western India and these are ordinary kriging (OK), universal kriging (UK)/kriging with eternal drift (KED), random forest regression and regression kriging (RK). Apart from legacy soil data, information on auxiliary and environmental variables e.g. soil map, terrain attributes and bioclimatic variables were used in the DSM methodology. Trend of covariates were fitted using random forest regression and the R2 of fitted trend was found 0.21–0.28. The accuracy of the prepared digital products was evaluated through k-fold cross validation approach. Lin's concordance correlation coefficient (LCCC) was found 0.47–0.55 for KED, 0.45–0.51 for RK, 0.43–0.51 for random forest regression and 0.28–0.43 for OK. Apart from LCCC, other evaluation indices e.g. R2, root mean squared error (RMSE) and bias also showed the best performance of KED to predict sand content followed by RK, random forest regression and OK. The prepared digital products will be quite useful to take decisions on appropriate and region specific soil managements. The prepared maps may further be uploaded in web map services for its wider access by end users.

Pub.: 27 Mar '17, Pinned: 04 May '17

Testing the Bannock detachment breakaway: Negative results support moderate- to high-angle splay system and domino-style fault block rotation along the Valley fault, southern Portneuf Range, southeastern Idaho, U.S.A.

Abstract: New geologic mapping, kinematic analysis, and tephrochronologic age correlations were completed in the southern Portneuf Range of southeast Idaho to characterize the Valley fault, a large-offset normal fault interpreted as the breakaway for the regionally extensive Bannock detachment system. The Valley fault separates ~11.8–7.57 Ma Salt Lake Formation from underlying Neoproterozoic to Cambrian Brigham Group and Cambrian rocks. Three-point problems indicate that the Valley fault strikes north–northwest (NNW) and dips an average of 9° west–southwest (WSW), in stark contrast to previous work, which interpreted the fault as steeply west-dipping. Footwall strata strike NNW and dip 37 ± 11° east–northeast (ENE). Measured bedding-to-fault cutoff angles are, therefore, ~46 ± 11°. Hanging-wall strata strike NNW and dip 20 ± 5° ENE adjacent to the fault and steepen progressively down-section to ~70 ± 10° ENE due to the Valley fault's minor listricity and multiple hanging-wall splays. Beneath the Miocene strata, Cambrian hanging-wall bedrock strike NNW and dip 55 ± 10° ENE. Adding a 9° Valley fault dip to these bedding dips yields cutoff angles of 29° to 80° for Miocene strata and 64° for hanging-wall bedrock. Top-to-the-west, dip-slip offset across the Valley fault and its hanging-wall splays—using the Miocene unconformity as a marker—is 13.7 ± 1 km. The older, subhorizontal Mine Hollow fault has 1,000 ± 300 m top-to-the-west normal offset. The initial dip of the Valley fault is interpreted to have been steeper than its present 9° dip. If footwall strata were subhorizontal prior to extension, as indicated by reconstruction of the Miocene unconformity, then the Valley fault had an initial dip of 46 ± 11° WSW based on measured bedding-to-fault angles. Combined with the modern low dip of the Valley fault, these data are interpreted to indicate that the Salt Lake Formation accumulated as growth strata adjacent to the active Valley fault, while the fault as well as footwall and hanging-wall strata tilted northeast through time. The Valley fault's mildly listric shape, the progressive domino-style tilting, and the large amount of total slip suggest that the Valley fault is a Basin-Range normal fault rather than a low-angle breakaway fault for the Bannock detachment system. The preferred model for extension in the region is ~7 km of uplift and exhumation during two phases of moderate- to high-angle domino-style fault block rotation. First, the Valley fault splays and Mine Hollow fault accommodated 5 km of extension between 11.8 to 9.16 Ma; then the Valley fault accommodated 10 km offset between 9.16 to

Pub.: 08 Dec '15, Pinned: 04 May '17

Along-fault migration of the Mount McKinley restraining bend of the Denali fault defined by late Quaternary fault patterns and seismicity, Denali National Park & Preserve, Alaska

Abstract: The tallest mountain in North America, Denali (formerly Mount McKinley, 6,190 m), is situated inside a sharp bend in the right-lateral strike-slip Denali fault. This anomalous topography is clearly associated with the complex geometry of the Denali fault, but how this restraining bend has evolved in conjunction with the regional topography is unknown. To constrain how this bend in the Denali fault is deforming, we document the Quaternary fault-related deformation north of the Denali fault through combined geologic mapping, active fault characterization, and analysis of background seismicity. Our mapping illustrates an east–west change in faulting style where normal faults occur east of the fault bend and thrust faults predominate to the west. The complex and elevated regional seismicity corroborates the style of faulting adjacent to the fault bend and provides additional insight into the change in local stress field in the crust adjacent to the bend. The style of active faulting and seismicity patterns define a deforming zone that accommodates the southwestward migration of this restraining bend. Fault slip rates for the active faults north of the Denali fault, derived from offset glacial outwash surfaces, indicate that the Mount McKinley restraining bend is migrating along the Denali fault at a late Pleistocene/Holocene rate of ~ 2–6 mm/yr. Ongoing thermochronologic and structural studies of the Mount McKinley restraining bend will extend these constraints on the migration and evolution of the restraining bend deeper in time and to the south of the Denali fault.

Pub.: 13 May '16, Pinned: 04 May '17

Geomorphology of the Burnt River, eastern Oregon, USA: Topographic adjustments to tectonic and dynamic deformation

Abstract: Eastern Oregon contains the deepest gorge in North America, where the Snake River cuts vertically down 2300 m. This deep gorge is known as Hells Canyon. A landscape containing such a topographic feature is likely undergoing relatively recent deformation. Study of the Burnt River, a tributary to the Snake River at the upstream end of Hells Canyon, yields data on active river incision in eastern Oregon, indicating that Quaternary faults are a first order control on regional landscape development. Through 1:24,000-scale geologic mapping, a 500,000-year record of fluvial incision along the Burnt River was constructed and is chronologically anchored by optically stimulated luminescence dating and tephrochronology analyses. A conceptual model of fluvial terrace formation was developed using these ages and likely applies to other non-glaciated catchments in eastern Oregon. Mapped terraces, inferred to have formed during glacial-interglacial cycles, provide constraints on rates of incision of the Burnt River. Incision through these terraces indicates that the Burnt River is down-cutting at 0.15 to 0.57 m kyr− 1. This incision appears to reflect a combination of local base-level adjustments tied to movement along the newly mapped Durkee fault and regional base-level control imposed by the downcutting of the Snake River. Deformation of terraces as young as 38.7 ± 5.1 ka indicates Quaternary activity along the Durkee fault, and when combined with topographic metrics (slope, relief, hypsometry, and stream-steepness), reveals a landscape in disequilibrium. Longer wavelength lithospheric dynamics (delamination and crustal foundering) that initiated in the Miocene may also be responsible for continued regional deformation of the Earth's surface.

Pub.: 24 Oct '16, Pinned: 04 May '17

Geological mapping of Sputnik Planitia on Pluto

Abstract: The geology and stratigraphy of the feature on Pluto informally named Sputnik Planitia is documented through geologic mapping at 1:2,000,000 scale. All units that have been mapped are presently being affected to some degree by the action of flowing N2 ice. The N2 ice plains of Sputnik Planitia display no impact craters, and are undergoing constant resurfacing via convection, glacial flow and sublimation. Condensation of atmospheric N2 onto the surface to form a bright mantle has occurred across broad swathes of Sputnik Planitia, and appears to be partly controlled by Pluto's obliquity cycles. The action of N2 ice has been instrumental in affecting uplands terrain surrounding Sputnik Planitia, and has played a key role in the disruption of Sputnik Planitia's western margin to form chains of blocky mountain ranges, as well in the extensive erosion by glacial flow of the uplands to the east of Sputnik Planitia.

Pub.: 17 Jan '17, Pinned: 04 May '17

Stratigraphic record of Pliocene-Pleistocene basin evolution and deformation within the Southern San Andreas Fault Zone, Mecca Hills, California

Abstract: A thick section of Pliocene-Pleistocene nonmarine sedimentary rocks exposed in the Mecca Hills, California, provides a record of fault-zone evolution along the Coachella Valley segment of the San Andreas fault (SAF). Geologic mapping, measured sections, detailed sedimentology, and paleomagnetic data document a 3–5 Myr history of deformation and sedimentation in this area. SW-side down offset on the Painted Canyon fault (PCF) starting ~ 3.7 Ma resulted in deposition of the Mecca Conglomerate southwest of the fault. The lower member of the Palm Spring Formation accumulated across the PCF from ~ 3.0 to 2.6 Ma during widespread subsidence. SW-side up slip on the PCF and related transpressive deformation from ~ 2.6 to 2.3 Ma created a time-transgressive angular unconformity between the lower and upper members of the Palm Spring Formation. The upper member accumulated in discrete fault-bounded depocenters until initiation of modern deformation, uplift, and basin inversion starting at ~ 0.7 Ma.

Pub.: 28 Mar '17, Pinned: 04 May '17