Geological Engineering Commons^™

Final Inversion Of The Midcontinent Rift During The Rigolet Phase Of The Grenvillian Orogeny, Eben B. Hodgin, Nicholas L. Swanson-Hysell, James M. Degraff, Andrew R.C. Kylander-Clark, Mark D. Schmitz, Andrew C. Turner, Yiming Zhang, Daniel A. Stolper

Michigan Tech Publications

Despite being a prominent continental-scale feature, the late Mesoproterozoic North American Midcontinent Rift did not result in the break-up of Laurentia, and subsequently underwent structural inversion. The timing of inversion is critical for constraining far-field effects of orogenesis and processes associated with the rift’s failure. The Keweenaw fault in northern Michigan (USA) is a major thrust structure associated with rift inversion; it places ca. 1093 Ma rift volcanic rocks atop the post-rift Jacobsville Formation, which is folded in its footwall. Previous detrital zircon (DZ) U-Pb geochronology conducted by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) assigned a ca. 950 Ma maximum …

Sources Of Hydrothermal Fluids Inferred From Oxygen And Carbon Isotope Composition Of Calcite, Keweenaw Peninsula Native Copper District, Michigan, Usa, Thomas Bodden, Theodore J. Bornhorst, Florence Bégué, Chad Deering

Michigan Tech Publications

The Mesoproterozoic North American Midcontinent Rift hosts the world’s largest accu-mulation of native copper in Michigan’s Keweenaw Peninsula. During a regional metamorpho-genic‐hydrothermal event, native copper was deposited along with spatially zoned main‐stage minerals in a thermal high. This was followed by deposition of late‐stage minerals including minor copper sulfide. Inferences from the oxygen and carbon isotopic composition of main‐stage hydrothermal fluids, as calculated from 296 new and compiled isotopic measurements on calcite, are consistent with existing models that low‐sulfur saline native copper ore‐forming fluids were domi-nantly derived by burial metamorphic processes from the very low sulfur basalt‐dominated rift fill at …

A New Stefan Equation To Characterize The Evolution Of Thermokarst Lake And Talik Geometry, Noriaki Ohara, Benjamin M. Jones, Andrew D. Parsekian, Kenneth M Hinkel, Katsu Yamatani, Mikhail Kanevskiy, Rodrigo C. Rangel, Amy L. Breen, Helena Bergstedt

Michigan Tech Publications

Thermokarst lake dynamics, which play an essential role in carbon release due to permafrost thaw, are affected by various geomorphological processes. In this study, we derive a three-dimensional (3D) Stefan equation to characterize talik geometry under a hypothetical thermokarst lake in the continuous permafrost region. Using the Euler equation in the calculus of variations, the lower bounds of the talik were determined as an extremum of the functional describing the phase boundary area with a fixed total talik volume. We demonstrate that the semi-ellipsoid geometry of the talik is optimal for minimizing the total permafrost thaw under the lake for …

Meteorite Impact Craters As Hotspots For Mineral Resources And Energy Fuels: A Global Review, S. James, Saranya R. Chandran, M. Santosh, A. P. Pradeepkumar, M. N. Praveen, K. S. Sajinkumar

Michigan Tech Publications

The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last few decades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings. As of today, 60 of the 208 terrestrial craters have been identified to host diverse resources such as hydrocarbons, metals and construction materials. The potential of craters as plausible resource contributors to the energy sector is therefore, worthy of consideration, as 42 (70%) of the 60 craters host energy resources such as oil, gas, coal, uranium, mercury, critical and major minerals as well as hydropower resources. Among …

Remote Sensing For Energy Resources: Introduction, K. S. Sajinkumar, Thomas Oommen

Michigan Tech Publications

No abstract provided.

Insar As A Tool For Monitoring Hydropower Projects: A Review, J. Aswathi, R. B. Binoj Kumar, Thomas Oommen, E. H. Bouali, K. S. Sajinkumar

Michigan Tech Publications

This paper provides a review of using Interferometric Synthetic Aperture Radar (InSAR), a microwave remote sensing technique, for deformation monitoring of hydroelectric power projects, a critical infrastructure that requires consistent and reliable monitoring. Almost all major dams around the world were built for the generation of hydropower. InSAR can enhance dam safety by providing timely settlement measurements at high spatial-resolution. This paper provides a holistic view of different InSAR deformation monitoring techniques such as Differential Synthetic Aperture Radar Interferometry (DInSAR), Ground-Based Synthetic Aperture Radar (GBInSAR), Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR), Multi-Temporal Interferometric Synthetic Aperture Radar (MTInSAR), Quasi-Persistent Scatterer …

Skip Nav Destination Research Article| March 16, 2022 Assessing The Effect Of Melt Extraction From Mushy Reservoirs On Compositions Of Granitoids: From A Global Database To A Single Batholith, J. Cornet, O. Bachmann, J. Ganne, A. Fiedrich, C. Huber, C. D. Deering, X. Feng

Michigan Tech Publications

Mafic and ultramafic plutonic rocks are often considered to be crystal cumulates (i.e., they are melt-depleted), but such a classification is much more contentious for intermediate to silicic granitoids (e.g., tonalite, granodiorite, granite, and syenite). Whether or not a given plutonic rock has lost melt to feed shallower subvolcanic intrusive bodies or volcanic edifices has key implications for understanding igneous processes occurring within the crust throughout the evolution of the Earth. We use statistical analyses of a global volcanic and plutonic rock database to show that most mafic to felsic plutonic rock compositions can be interpreted as melt-depleted (i.e., most …

Integrated Parametric Graph Closure And Branch-And-Cut Algorithm For Open Pit Mine Scheduling Under Uncertainty, Devendra Joshi, Amol Paithankar, Snehamoy Chatterjee, Sk Md Equeenuddin

Michigan Tech Publications

Open pit mine production scheduling is a computationally expensive large-scale mixed-integer linear programming problem. This research develops a computationally efficient algorithm to solve open pit production scheduling problems under uncertain geological parameters. The proposed solution approach for production scheduling is a two-stage process. The stochastic production scheduling problem is iteratively solved in the first stage after relaxing resource constraints using a parametric graph closure algorithm. Finally, the branch-and-cut algorithm is applied to respect the resource constraints, which might be violated during the first stage of the algorithm. Six small-scale production scheduling problems from iron and copper mines were used to …

Lava Volume From Remote Sensing Data: Comparisons With Reverse Petrological Approaches For Two Types Of Effusive Eruption, Pauline Verdurme, Simon Carn, Andrew J.L. Harris, Diego Coppola, Andrea Di Muro, Santiago Arellano, Lucia Gurioli

Michigan Tech Publications

Five effusive eruptions of Piton de la Fournaise (La Réunion) are analyzed to investigate temporal trends of erupted mass and sulfur dioxide (SO2) emissions. Daily SO2 emissions are acquired from three ultraviolet (UV) satellite instruments (the Ozone Monitoring Instrument (OMI), the Ozone Mapping and Profiler Suite (OMPS), and the Tropospheric Monitoring Instrument (TROPOMI)) and an array of ground-based UV spectrometers (Network for Observation of Volcanic and Atmospheric Change (NOVAC)). Time-averaged lava discharge rates (TADRs) are obtained from two automatic satellite-based hot spot detection systems: MIROVA and MODVOLC. Assuming that the lava volumes measured in the field are accurate, the MIROVA …

Continental Magmatism And Uplift As The Primary Driver For First-Order Oceanic 87sr/86sr Variability With Implications For Global Climate And Atmospheric Oxygenation, Timothy Paulsen, Chad Deering, Jakub Sliwinski, Snehamoy Chatterjee, Olivier Bachman

Michigan Tech Publications

Oceans cover 70% of Earth's surface, setting it apart from the other terrestrial planets in the solar system, but the mechanisms driving oceanic chemical evolution through time remain an important unresolved problem. Imbalance in the strontium cycle, introduced, for example, by increases in continental weathering associated with mountain building, has been inferred from shifts in marine carbonate 87Sr/86Sr ratios. There are, however, uncertainties about the spatial and temporal patterns of crustal evolution in Earth's past, particularly for the period leading up to the Cambrian explosion of life. Here we show that U-Pb age and trace element data from a global …

A Comparison Of Multiple Machine Learning Algorithms To Predict Whole-Body Vibration Exposure Of Dumper Operators In Iron Ore Mines In India, Rahul Upadhyay, Amrites Senapati, Ashis Bhattacherjee, Aditya Kumar Patra, Snehamoy Chatterjee

Michigan Tech Publications

Background: This study deals with some factors that influence the exposure of whole-body vibration (WBV) of dumper operators in surface mines. The study also highlights the approach to improve the multivariate linear analysis outcomes when collinearity exists between certain factor pairs.

Material and Methods: A total number of 130 vibration readings was taken from two adjacent surface iron ore mines. The frequency-weighted RMS acceleration was used for the WBV exposure assessment of the dumper operators. The factors considered in this study are age, weight, seat backrest height, awkward posture, the machine age, load tonnage, dumper speed and haul …

Earth Imaging From The Surface Of The Moon With A Dscovr/Epic-Type Camera, Nick Gorkavyi, Simon Carn, Matt Deland, Yuri Knyazikhin, Nick Krotkov, Alexander Marshak, Et Al.

Michigan Tech Publications, Part 2

The Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) satellite observes the entire Sun-illuminated Earth from sunrise to sunset from the L1 Sun-Earth Lagrange point. The L1 location, however, confines the observed phase angles to ∼2°–12°, a nearly backscattering direction, precluding any information on the bidirectional surface reflectance factor (BRF) or cloud/aerosol phase function. Deploying an analog of EPIC on the Moon’s surface would offer a unique opportunity to image the full range of Earth phases, including observing ocean/cloud glint reflection for different phase angles; monitoring of transient volcanic clouds; detection of circum-polar mesospheric and stratospheric …

Remote Sensing-Based Statistical Approach For Defining Drained Lake Basins In A Continuous Permafrost Region, North Slope Of Alaska, Helena Bergstedt, Benjamin M. Jones, Kenneth M Hinkel, Louise Farquharson, Benjamin V. Gaglioti, Andrew D. Parsekian, Mikhail Kanevskiy, Noriaki Ohara, Amy L. Breen, Rodrigo C. Rangel, Guido Grosse, Ingmar Nitze

Michigan Tech Publications

Lake formation and drainage are pervasive phenomena in permafrost regions. Drained lake basins (DLBs) are often the most common landforms in lowland permafrost regions in the Arctic (50% to 75% of the landscape). However, detailed assessments of DLB distribution and abundance are limited. In this study, we present a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions, using the North Slope of Alaska as a case study. We validated this first North Slope-wide DLB data product against several previously published sub-regional scale datasets and manually classified points. The study area covered >71,000 km2, including a …

Characterizing Soil Stiffness Using Thermal Remote Sensing And Machine Learning, Jordan Ewing, T. Oommen, Paramsothy Jayakumar, Russell Alger

Michigan Tech Publications

Soil strength characterization is essential for any problem that deals with geomechanics, including terramechanics/terrain mobility. Presently, the primary method of collecting soil strength parameters through in situ measurements but sending a team of people out to a site to collect data this has significant cost implications and accessing the location with the necessary equipment can be difficult. Remote sensing provides an alternate approach to in situ measurements. In this lab study, we compare the use of Apparent Thermal Inertia (ATI) against a GeoGauge for the direct testing of soil stiffness. ATI correlates with stiffness, so it allows one to predict …

Potentials Of Airborne Hyperspectral Aviris-Ng Data In The Exploration Of Base Metal Deposit—A Study In The Parts Of Bhilwara, Rajasthan, Arindam Guha, Uday Kumar Ghosh, Joyasree Sinha, Amin Beiranvand Pour, Ratnakar Bhaisal, Snehamoy Chatterjee, Nikhil Kumar Baranval, Nisha Rani, K. Vinod Kumar, Pamaraju V.N. Rao

Michigan Tech Publications

In this study, we have processed the spectral bands of airborne hyperspectral data of Advanced Visible Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) data for delineating the surface signatures associated with the base metal mineralization in the Pur-Banera area in the Bhilwara district, Rajasthan, India.The primaryhost rocks of the Cu, Pb, Zn mineralization in the area are Banded Magnetite Quartzite (BMQ), unclassified calcareous silicates, and quartzite. We used ratio images derived from the scale and root mean squares (RMS) error imagesusing the multi-range spectral feature fitting (MRSFF) methodto delineate host rocks from the AVIRIS-NG image. The False Color Composites (FCCs) of different …

Global Health Effects Of Future Atmospheric Mercury Emissions, Yanxu Zhang, Zhengcheng Song, Shaojian Huang, Peng Zhang, Yiming Peng, Peipei Wu, Jing Gu, Stephanie Dutkiewicz, Huanxin Zhang, Shiliang Wu, Feiyue Wang, Long Chen, Shuxiao Wang, Ping Li

Michigan Tech Publications

Mercury is a potent neurotoxin that poses health risks to the global population. Anthropogenic mercury emissions to the atmosphere are projected to decrease in the future due to enhanced policy efforts such as the Minamata Convention, a legally-binding international treaty entered into force in 2017. Here, we report the development of a comprehensive climate-atmosphere-land-ocean-ecosystem and exposure-risk model framework for mercury and its application to project the health effects of future atmospheric emissions. Our results show that the accumulated health effects associated with mercury exposure during 2010–2050 are $19 (95% confidence interval: 4.7–54) trillion (2020 USD) realized to 2050 (3% discount …

Calculation Of Real Evapotranspiration By The Application Of Metric Method On Landsat-8 Data, Ali Imanian, Majid Hashemi Tangestani, Adel Asadi, Mohammad Zare

Michigan Tech Publications

In geological remote sensing approaches for estimating evapotranspiration, METRIC method is among the most modern and precise approaches that many positive experiments have been reported regarding its applicability. In this study, the value of actual evapotranspiration (ET) occurred in Marvdasht farmlands, Fars province, Iran, was calculated instantaneously (hourly) and daily (24 hours), at 24 April 2017 using METRIC method and Lansat-8 data. In order to accuracy assessment of the results, estimated values were compared to the values calculated with Penman Monteith method in places that covers by alfafa crop. Our observations showed that ET values obtained via METRIC model on …

Effect Of Spectral Bandwidths On Linear Feature Extraction: An Evaluation Of Landsat Etm+ And Oli Sensors, Ali Imanian, Adel Asadi, Majid Hashemi Tangestani, Saeid Homayouni, Ali Faghih

Michigan Tech Publications

Hitherto there have been many studies comparing the usefulness of OLI and ETM+ sensors for linear feature extraction. However, not too much attention has been paid to the differences in the bandwidth of the two sensors. In this study, the suitability of Landsat ETM+ and OLI sensors for automatic detection of linear features by LINE algorithm was compared. In this study, eight regions in northern, central and southern parts of Iran were selected based on the diversity of lithology, the pristine status, and lack of human activities for the comparison of the two datasets. Results revealed that LINE algorithm performed …

Version 2 Ozone Monitoring Instrument So2 Product (Omso2 V2): New Anthropogenic So2 Vertical Column Density Dataset, Can Li, Nickolay A. Krotkov, Peter J.T. Leonard, Simon Carn, Joanna Joiner, Robert J.D. Spurr, Alexander Vasilkov

Michigan Tech Publications

The Ozone Monitoring Instrument (OMI) has been providing global observations of SO2 pollution since 2004. Here we introduce the new anthropogenic SO2 vertical column density (VCD) dataset in the version 2 OMI SO2 product (OMSO2 V2). As with the previous version (OMSO2 V1.3), the new dataset is generated with an algorithm based on principal component analysis of OMI radiances but features several updates. The most important among those is the use of expanded lookup tables and model a priori profiles to estimate SO2 Jacobians for individual OMI pixels, in order to better characterize pixel-to-pixel variations in SO2 sensitivity including over …

Constructing A Complete Landslide Inventory Dataset For The 2018 Monsoon Disaster In Kerala, India, For Land Use Change Analysis, Lina Hao, Rajaneesh A., Cees Van Westen, Sajinkumar K. S., Tapas Ranjan Martha, Pankaj Jaiswal, Brian G. Mcadoo

Michigan Tech Publications

Event-based landslide inventories are important for analyzing the relationship between the intensity of the trigger (e.g., rainfall, earthquake) and the density of the landslides in a particular area as a basis for the estimation of the landslide probability and the conversion of susceptibility maps into hazard maps required for risk assessment. They are also crucial for the establishment of local rainfall thresholds that are the basis of early warning systems and for evaluating which land use and land cover changes are related to landslide occurrence. The completeness and accuracy of event-based landslide inventories are crucial aspects to derive reliable results …

Using Tandem-X To Measure Pyroclastic Flow Source Location, Thickness And Volume: Application To The 3rd June 2018 Eruption Of Fuego Volcano, Guatemala, F. Albino, J. Biggs, R. Escobar-Wolf, A. Naismith, M. Watson, J. C. Phillips, G. A. Chigna Marroquin

Michigan Tech Publications

The estimation of the volume of volcanic flows during an ongoing eruption is challenging but this information is crucial for improving risk assessment and for forecasting future events. Although previous studies have shown the ability of TanDEM-X satellite data to derive the thickness and the volume of lava flow fields during effusive eruptions, the method has not been explored yet for pyroclastic flows. Using bi-static interferometry, we produce TanDEM-X DEM on Fuego volcano (Guatemala) to measure the significant topographic changes caused by the 3rd June 2018 eruption, which destroyed the town of San Miguel Los Lotes. We estimate the volume …

Effect Of Geometry And Fluid Viscosity On Dynamics Of Fluid-Filled Cracks: Insights From Analog Experimental Observations, Haitao Cao, Ezequiel F. Medici, Gregory P. Waite, Roohollah Askari

Michigan Tech Publications

Fluid-filled volumes in geological systems can change the local stress field in the host rock and may induce brittle deformation as well as crack propagation. Although the mechanisms relating fluid pressure perturbations and seismicity have been widely studied, the fluid-solid interaction inside the crack of a host rock is still not well understood. An analog experimental model of fluid intrusion in cracks between planar layers has been developed to study stress conditions at the margins and tips. A combined high-speed shadowgraph and a photoelasticity imaging system is used to visualize the fluid dynamics and induced stresses on the solid matrix. …

Design And Development Of A Machine Vision System Using Artificial Neural Network-Based Algorithm For Automated Coal Characterization, Amit Kumar Gorai, Simit Raval, Ashok Kumar Patel, Snehamoy Chatterjee, Tarini Gautam

Michigan Tech Publications

Coal is heterogeneous in nature, and thus the characterization of coal is essential before its use for a specific purpose. Thus, the current study aims to develop a machine vision system for automated coal characterizations. The model was calibrated using 80 image samples that are captured for different coal samples in different angles. All the images were captured in RGB color space and converted into five other color spaces (HSI, CMYK, Lab, xyz, Gray) for feature extraction. The intensity component image of HSI color space was further transformed into four frequency components (discrete cosine transform, discrete wavelet transform, discrete Fourier …

Global Aeolian Dust Variations And Trends: A Revisit Of Dust Event And Visibility Observations From Surface Weather Stations, Xin Xi

Michigan Tech Publications

This study revisits the use of horizontal visibility and manually reported present weather (ww) records from the NOAA Integrated Surface Database (ISD) for characterizing the aeolian dust variability and recent trends over the globe and three largest source regions (North Africa, Middle East, and East Asia). Due to its qualitative nature, ww is combined with visibility to derive a new variable, VI, which has higher correlations with the dust emission and burden from satellite observations and global aerosol reanalyses than does the dust event frequency (FR) derived from ww only. Both FR and VI capture …

Utilizing Hyperspectral Remote Sensing For Soil Gradation, Jordan Ewing, T. Oommen, Paramsothy Jayakumar, Russell Alger

Michigan Tech Publications

Soil gradation is an important characteristic for soil mechanics. Traditionally soil gradation is performed by sieve analysis using a sample from the field. In this research, we are interested in the application of hyperspectral remote sensing to characterize soil gradation. The specific objective of this work is to explore the application of hyperspectral remote sensing to be used as an alternative to traditional soil gradation estimation. The advantage of such an approach is that it would provide the soil gradation without having to obtain a field sample. This work will examine five different soil types from the Keweenaw Research Center …

Flow Simulation Considering Adsorption Boundary Layer Based On Digital Rock And Finite Element Method, Yong Fei Yang, Ke Wang, Qian Fei Lv, Roohollah Askari, Qing Yan Mei, Jun Yao, Jie Xin Hou, Kai Zhang, Ai Fen Li, Chen Chen Wang

Michigan Tech Publications

Due to the low permeability of tight reservoirs, throats play a significant role in controlling fluid flow. Although many studies have been conducted to investigate fluid flow in throats in the microscale domain, comparatively fewer works have been devoted to study the effect of adsorption boundary layer (ABL) in throats based on the digital rock method. By considering an ABL, we investigate its effects on fluid flow. We build digital rock model based on computed tomography technology. Then, microscopic pore structures are extracted with watershed segmentation and pore geometries are meshed through Delaunay triangulation approach. Finally, using the meshed digital …

Paleomagnetic Evidence For Modern-Like Plate Motion Velocities At 3.2 Ga, Alec R. Brenner, Roger R. Fu, David A.D. Evans, Aleksey V. Smirnov, Raisa Trubko, Ian R. Rose

Michigan Tech Publications

The mode and rates of tectonic processes and lithospheric growth during the Archean [4.0 to 2.5 billion years (Ga) ago] are subjects of considerable debate. Paleomagnetism may contribute to the discussion by quantifying past plate velocities. We report a paleomagnetic pole for the ~3180 million year (Ma) old Honeyeater Basalt of the East Pilbara Craton, Western Australia, supported by a positive fold test and micromagnetic imaging. Comparison of the 44°±15° Honeyeater Basalt paleolatitude with previously reported paleolatitudes requires that the average latitudinal drift rate of the East Pilbara was ≥2.5 cm/year during the ~170 Ma preceding 3180 Ma ago, a …

A New Discrete Wavelength Backscattered Ultraviolet Algorithm For Consistent Volcanic So2 Retrievals From Multiple Satellite Missions, Bradford L. Fisher, Nickolay A. Krotkov, Pawan K. Bhartia, Can Li, Simon Carn, Eric Hughes, Peter J. T. Leonard

Michigan Tech Publications

This paper describes a new discrete wavelength algorithm developed for retrieving volcanic sulfur dioxide (SO₂) vertical column density (VCD) from UV observing satellites. The Multi-Satellite SO₂ algorithm (MS_SO2) simultaneously retrieves column densities of sulfur dioxide, ozone, and Lambertian effective reflectivity (LER) and its spectral dependence. It is used operationally to process measurements from the heritage Total Ozone Mapping Spectrometer (TOMS) onboard NASA's Nimbus-7 satellite (N7/TOMS: 1978–1993) and from the current Earth Polychromatic Imaging Camera (EPIC) onboard Deep Space Climate Observatory (DSCOVR: 2015–ongoing) from the Earth–Sun Lagrange (L1) orbit. Results from MS_SO2 algorithm for several volcanic cases were …

Volcano Monitoring From Space Using High-Cadence Planet Cubesat Images Applied To Fuego Volcano, Guatemala, Anna Aldeghi, Simon Carn, Rudiger Escobar-Wolf, Gianluca Groppelli

Michigan Tech Publications

Fuego volcano (Guatemala) is one of the most active and hazardous volcanoes in the world. Its persistent activity generates lava flows, pyroclastic density currents (PDCs), and lahars that threaten the surrounding areas and produce frequent morphological change. Fuego’s eruption deposits are often rapidly eroded or remobilized by heavy rains and its constant activity and inaccessible terrain makes ground-based assessment of recent eruptive deposits very challenging. Earth-orbiting satellites can provide unique observations of volcanoes during eruptive activity, when ground-based techniques may be too hazardous, and also during inter-eruptive phases, but have typically been hindered by relatively low spatial and temporal resolution. …

Analysis Of An Updated Paleointensity Database (Qpi‐Pint) For 65–200 Ma: Implications For The Long‐Term History Of Dipole Moment Through The Mesozoic, E. V. Kulakov, C. J. Sprain, P. V. Doubrovine, A. V. Smirnov, G. A. Paterson, L. Hawkins, L. Fairchild, E. J. Piispa, A. J. Biggin

Michigan Tech Publications

The global paleointensity database for 65–200 Ma was analyzed using a modified suite of paleointensity quality criteria (Q_PI) such that the likely reliability of measurements is assessed objectively and as consistently as possible across the diverse data set. This interval was chosen because of dramatic extremes of geomagnetic polarity reversal frequency ranging from greater than 10 reversals per million years in the Jurassic hyperactivity period (155–171 Ma) to effectively zero during the Cretaceous Normal Superchron (CNS; 84–126 Ma). Various attempts to establish a relationship between the strength of Earth's magnetic field and the reversal frequency have been made …