Geochemistry Commons^™

Preservation Of Sedimentary Rubidium Isotopic Signatures In Subduction Zones: Insights From The Schistes Lustrés Hp-Uhp Metasediments, Western Alps, Mary Clarich

UNLV Theses, Dissertations, Professional Papers, and Capstones

When oceanic plates bend and sink into the mantle at subduction zones, they carry sediments from the surface down into the mantle. The recycled sediments contain elements, that are depleted in the mantle, thereby influencing the composition of the mantle wedge and the formation of arc magmas, which are the building blocks of juvenile continental crust. However, it remains poorly constrained how much these elements, particularly fluid-mobile elements such as rubidium (Rb), are lost into fluids during metamorphic dehydration, and how much is transported to sub-arc depths where arc magmas are generated. Rubidium in subducting sediments is mainly hosted in …

Reconstructing Central American Hydroclimate Changes Across Time From Isotopic Signatures In Modern And Paleo-Rainfall Records, Giuseppe Lucia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Tropical monsoon rainfall is a key component of Earth’s climate system and supports the livelihood and economy of billions of people. Yet, projections of future monsoons remain highly uncertain, particularly in regions with distinct physiography and complex land-ocean-atmosphere interactions like Central America, where long and continuous high-resolution paleoclimate data to test climate model simulations are still limited. This series of studies aims to reconstruct monsoon dynamics and underlying forcing controls in Central America on multiple timescales by the analysis and integration of stable isotope data in modern and paleo-rainfall records from Guatemala.

In Chapter 2, I present a daily-resolution, two-year-long …

Mechanisms Of Gold Enrichment In Seafloor Massive Sulfide Deposits: A Study On The Higashi-Aogashima Hydrothermal Field, Claudia Martinez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The study of Seafloor Massive Sulfides (SMS) deposit formation is vital for assessing both the economic potential and environmental risks posed by future marine mining projects. Metal-rich SMS deposits form in hydrothermal vent systems within tectonically active regions, such as back-arc basins, where faults enhance crustal permeability, enabling fluid migration driven by magmatic heat sources at depth in the crust. Currently our understanding of SMS formation processes is based on bulk-rock geochemical and isotopic data, lacking the necessary spatial and temporal resolution to understand ore forming processes. As a result, critical gaps remain in understanding the exact mechanisms responsible for …

Analyzing Fe/Mg-Silicate Chemical Gardens As Analogs To Silicate-Rich Hydrothermal Chimneys On Early Earth And Mars, Nancy Alejandra Carman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrothermal systems have been proposed as environments for prebiotic chemistry on early Earth. Ancient Mars was an ocean world and could also have had hydrothermal vents supporting biological or prebiotic processes. The Strytan Hydrothermal Field (SHF) in Iceland is a basalt-hosted alkaline vent that forms massive hydrothermal Mg-saponite chimneys and is a potential analog to basalt-hosted alkaline vents that may have existed at the Eridania basin on Mars, where saponite deposits are thought to have formed from ancient hydrothermal activity. Chemical garden experiments have previously been used to simulate aspects of hydrothermal chimney growth for other types of vent systems; …

Investigating Controls On Temporal And Spatial Variation Of Dissolved Uranium At Springs In Horn Creek Drainage, Grand Canyon National Park, Arizona, Usa, Collin Davidson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is a critical resource in the Grand Canyon, providing water to local communities, millions of annual visitors, and ecosystems. One major concern for this critical resource is the potential for uranium contamination in conjunction with uranium mining efforts. Upper Horn Bedrock Spring (UHB) in the Horn Creek drainage of the Grand Canyon sits below the oldest uranium mine in the region, Orphan Lode mine. UHB spring contains the highest concentration of dissolved uranium in the region, eclipsing the Maximum Contaminant Level (MCL) set by the USEPA by an order of magnitude on average. This research and recent collaboration with …

New Observations On The Age And Origin Of The Geologist Seamounts, South Hawaiian Seamount Province, Brandon Chester Scott

UNLV Theses, Dissertations, Professional Papers, and Capstones

Investigation into seamounts that stem from intraplate volcanism—that is volcanism occurring far from plate boundaries—presents an opportunity to deconvolve processes associated with mantle compositional heterogeneities and melting dynamics. Upwelling and decompression of thermochemically anomalous mantle plumes is the primary mechanism for significant intraplate volcanism; however, many seamounts dotted across the Pacific Plate do not correlate spatially, temporally, or geochemically with mantle plume volcanism. One region of enigmatic volcanism in the ocean basins that is not clearly attributable to plume-derived magmatism are the Geologist Seamounts and the wider South Hawaiian Seamount Province (∼19°N, 157°W). Here we present merged multibeam (<100 m) and satellite altimetry bathymetric maps of the Geologist Seamounts region, new ^{40 …}

Climatic Influences On Incipient Alteration In Mars-Relevant Ultramafic Soils, Anthony Feldman

UNLV Theses, Dissertations, Professional Papers, and Capstones

An ongoing debate exists around the nature of the climatic conditions present during the Noachian and early Hesperian periods (~4.1 to 3 Gyr ago) of Mars’ ancient history. The various theories put forward can reasonably be grouped into “warm and wet” vs “cold and icy” camps. Warm and wet approximates an Earth-like system with a relatively clement climate with significant liquid water present including potentially long-lived oceans. Cold and icy theories generally postulate thick ice sheets at high elevations with periodic warming events driving precipitation and the formation of river channels and leading to the formation of chemical alteration products. …

Magmatic Processes Leading To Compositional Diversity In The Mars Crust, Amanda Marie Ostwald

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ancient Mars crust can yield insights into planet formation and evolution that Earth cannot. Direct investigation of the martian surface is limited to studies on meteorites and rover-obtained analyses. The nakhlites and chassignites, two classes of martian meteorites, are together the largest suite of martian meteorites derived from a single location on the surface. As such, they present a rare opportunity to study the Mars crust in detail using samples bearing a contextual relationship. Rover studies have found a surprising amount of compositional diversity in surface materials, the formation mechanisms of which are not well-constrained. This dissertation leverages meteorites …

Study Of Trace Elements In Southern Nevada Spring Waters And Lakes, Hyejeong Lee

UNLV Theses, Dissertations, Professional Papers, and Capstones

Comprehending the natural water resource is imperative for the entire state of Nevada and of particular significance for Southern Nevada, where rapid population growth and climate change are placing significant strain on supplies. This research underscores the significance of water chemistry in identifying potential water source areas through trace elements. For the first time, the study proposed measuring the compositions of the entire suite of metal elements, ranging from Li to U, in over 40 springs in the Moapa Valley and its upper gradient valleys, utilizing the iCAP Qc ICP-MS (Inductively Coupled Plasma Mass Spectrometer) at UNLV. The research evaluated …

Paleoenvironmental Changes Across The Devonian-Carboniferous Transition, Audrey M. Warren

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Devonian-Carboniferous (D-C) transition was a critical interval in earth history, witnessing profound environmental changes associated with plant and animal evolution and extinction. Two first-order mass extinctions occurred leading up to the D-C boundary: the Kellwasser Event at the Frasnian-Famennian (F-F) boundary (~371 Ma) and the D-C boundary Hangenberg Event (~359 Ma). Both events were associated with significant sea level changes and major carbon cycle perturbations, evidenced by widespread deposition of black shale and positive carbon isotope (δ13C) excursions, all of which have been used to correlate these events across the globe. Because preservation of black shale requires anoxic conditions, …

Trace Element Behaviors During Igneous Evolution And Hydrothermal Alteration Of An Evolved Rhyolite, The Blawn Formation, Wah Wah Mountains, Utah: Implications For Critical Metal Abundances In Highly Evolved Rhyolites, Drew William Barkoff

UNLV Theses, Dissertations, Professional Papers, and Capstones

A-type rhyolites and granites often contain elevated concentrations of the rare earth elements (REE) and many other critical trace elements relative to I- and S-type rhyolites and granites. Their trace element-enriched nature makes them potentially prospective bulk tonnage, low-grade resources of the REE and many other critical trace elements, including Li, Be, Mo, Sn, and W, but little work has been performed to delineate their economic potential. The 22.1 Ma Red Beryl Rhyolite (RBR) and the 18.3 Ma Tetons Rhyolite (TR) units of the Blawn Formation represent two A-type rhyolite domes located in the southern Wah Wah Mountains of Utah. …

Combining Freestanding Ferroelectric Perovskite Oxides With Two-Dimensional Semiconductors For High Performance Transistors, Sergio Puebla, Thomas Pucher, Victor Rouco, Gabriel Sanchez-Santolino, Yong Xie, Victor Zamora, Fabian A. Cuellar, Federico J. Mompean, Carlos Leon, Carlos O. Island, Mar Garcia-Hernandez, Jacobo Santamaria, Carmen Munuera, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

We demonstrate the fabrication of field-effect transistors based on single-layer MoS2 and a thin layer of BaTiO3 (BTO) dielectric, isolated from its parent epitaxial template substrate. Thin BTO provides an ultrahigh-κ gate dielectric effectively screening Coulomb scattering centers. These devices show mobilities substantially larger than those obtained with standard SiO2 dielectrics and comparable with values obtained with hexagonal boron nitride, a dielectric employed for fabrication of high-performance two-dimensional (2D) based devices. Moreover, the ferroelectric character of BTO induces a robust hysteresis of the current vs gate voltage characteristics, attributed to its polarization switching. This hysteresis is strongly suppressed when the …

Antler Foreland Basin Evolution Recorded In Detrital Zircon U-Pb Geochronology, James Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Antler orogeny was a Devonian-Mississippian (375-320 Ma) mountain building event that occurred along the western Laurentian margin. The initiation of the Antler orogeny is marked by the emplacement of the Roberts Mountain Allochthon (RMA) that thrust Cambrian-Devonian deep water marine siliciclastic rocks 100 km eastward onto the western Laurentian margin. Shortening related to the Antler orogeny deformed RMA strata and caused a flexural response in the continental crust that resulted in the formation of the adjacent Antler Foreland basin. The paleogeographic history of the RMA strata and tectonic drivers for the Antler orogeny are still debated. Proposed models suggest …

Barriers To And Uncertainties In Understanding And Quantifying Global Critical Mineral And Element Supply, Brian A. Mcnulty, Simon M. Jowitt

Geoscience Faculty Research

The critical minerals and elements are natural substances that are essential to modern life but have insecure supply. This lack of a secure supply clashes with the increasing importance of these elements, especially given their use in technologies needed to reduce global CO2 emissions and mitigate against anthropogenic climate change. In this contribution we review the by-product nature of the critical minerals and elements and the inherant uncertainties in reported critical mineral and element annual production as well as the relationships between these commodities and main-product metals and associated concentrates. We explore the geological and geographical barriers to critical mineral …

Calcium Isotope Cosmochemistry, Maria C. Valdes, Katherine R. Bermingham, Shichun Huang, Justin I. Simon

Geoscience Faculty Research

The past decade has seen significant advancements in analytical capabilities and with it a marked increase in the use of Ca isotopes to advance our understanding of the Solar System's and Earth's evolution. Here, mass-dependent and non-mass-dependent Ca isotopic variations in bulk meteorites and chondrite components are discussed. This contribution also examines how Ca isotopes record nebular processes, including evaporation/condensation and mixing of chemically and isotopically distinct reservoirs in the protoplanetary disk. The applicability of non-mass-dependent Ca isotopic variations to tracing the nature and timing of stellar mass contributions to the parental molecular cloud is discussed. This includes the constraints …

Molybdenite Re–Os, Titanite And Garnet U–Pb Dating Of The Magushan Skarn Cu–Mo Deposit, Xuancheng District, Middle–Lower Yangtze River Metallogenic Belt, Yue Li, Feng Yuan, Simon M. Jowitt, Fangyue Wang, Xiangling Li, Yufeng Deng, Yunyue Wang, Taofa Zhou

Geoscience Faculty Research

© 2020 Elsevier B.V. The Magushan skarn Cu–Mo deposit is a representative example of the skarn mineralization occurring within the Xuancheng ore district of the Middle–Lower Yangtze River Metallogenic Belt of eastern China. The precise age of an ore deposit is important for understanding the timing of mineralization relative to other geological events in a region and to fully place the formation of a mineral deposit within the geological context of other processes that occur within the study area. Here, we present new molybdenite Re–Os and titanite and andradite garnet U–Pb ages for the Magushan deposit and use these data …

Petrogenesis Of Hawaiian Lavas: Investigations Using Radiogenic And Non-Traditional Stable Isotopes, Christopher Defelice

UNLV Theses, Dissertations, Professional Papers, and Capstones

Earth’s mantle is the most voluminous part of the planet and is inaccessible to direct investigations. It is only possible to study it through indirect methods, such as the chemical makeup of erupted lavas. The Hawaiian Islands are thought to be the product of the mantle plume hypothesis, sometimes called a hot spot. Material from the Earth’s mantle is brought to the surface and erupted as magnesium rich lavas and form basalts. Hawaii is the longest lived active hot spot on Earth and makes it an ideal candidate for understanding the evolution of the Earth’s mantle and how lavas cool …

Chronicling Magma Transit Beneath Hawaiian Volcanoes: Every Isotope A Word, Every Crystal A Story, Jonathan Pinko

UNLV Theses, Dissertations, Professional Papers, and Capstones

At many oceanic volcanoes, such as Hawaii, mantle-derived magmas migrate to crustal level magma chambers, where they accumulate before eruption. Understanding the magma chamber residence times, or the time gaps between the arrivals of new magmas and eruptions, is important in volcanic hazard mitigation. Here I apply iron and magnesium isotope effects in olivines to constrain these times at Hawaiian volcanoes. Combined with published data, I present bulk ?56Fe (-1.706 to 0.489) and ?26Mg (-0.400 to 0.356) in 108 Hawaiian olivines erupted from the pre-shield, shield, and post-shield stages. The Hawaiian olivine ?56Fe and ?26Mg represent the largest Fe-Mg isotope …

Manganese Oxides In Martian Meteorites Northwest Africa (Nwa) 7034 And 7533, Yang Liu, Woodward W. Fischer, Chi Ma, John R. Beckett, Oliver Tschauner, Yunbin Guan, Usha F. Lingappa, Samuel M. Webb, Vitali B. Prakapenka, Nina L. Lanza, Carl B. Agee

Geoscience Faculty Research

We report the discovery of indigenous Mn-oxides in Martian regolith breccias Northwest Africa (NWA) 7034 and 7533. These Mn-oxides occur in Mn-rich regions as nanocrystals mixed with silicates, FeOOH, and possible phosphates. The Mn-rich regions contain up to 34 wt% Mn and typically display large chemical gradients on the scale of 10–20 μm. The Martian origin of Mn-oxides was established by the presence of Mn-rich glass (4.8–5.6 wt% Mn) in the fusion crust that crosscuts a Mn-oxides-bearing monzonite clast and by the absence of Mn-oxides on the environmentally exposed surfaces (exterior and fractures) of the meteorites. Manganese K-edge X-ray absorption …

Increasing Analysis Efficiency Through Automation Of Inductively Coupled Plasma Mass Spectrometry (Icp-Ms) Data Reduction Process Using Python, Grace Abigail Martin

Undergraduate Research Symposium Posters

The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) provides elemental analysis through ionization of samples. Numerous geochemistry laboratories utilize the ICP-MS and has become a community standard. The ICP-MS data reduction process is time intensive and involves correction for blank contribution and sensitivity drift during measurement, as well as construction of standard calibration lines based on measurements of standard solutions. We look to decrease turnaround time and increase efficiency through automation of the data reduction process using Python. The ICP-MS data reduction process was 3 hours or more, in our observations. Python packages such as Openpyxl and Pandas, allow us to …

Nickel Isotopic Evidence For Late-Stage Accretion Of Mercury-Like Differentiated Planetary Embryos, Shui Jiong Wang, Wenzhong Wang, Jian Ming Zhu, Zhongqing Wu, Jingao Liu, Guilin Han, Fang Zhen Teng, Shichun Huang, Hongjie Wu, Yujian Wang, Guangliang Wu, Weihan Li

Geoscience Faculty Research

© 2021, The Author(s). Earth’s habitability is closely tied to its late-stage accretion, during which impactors delivered the majority of life-essential volatiles. However, the nature of these final building blocks remains poorly constrained. Nickel (Ni) can be a useful tracer in characterizing this accretion as most Ni in the bulk silicate Earth (BSE) comes from the late-stage impactors. Here, we apply Ni stable isotope analysis to a large number of meteorites and terrestrial rocks, and find that the BSE has a lighter Ni isotopic composition compared to chondrites. Using first-principles calculations based on density functional theory, we show that core-mantle …

Microbe-Mineral Interactions During Exceptional Fossil Preservation, Stromatolite Formation, And Desert Varnish Growth, Michael Strange

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Ediacaran to Cambrian Deep Spring Formation consists of mixed carbonate-siliciclastic strata which contain an increasingly complex and biogeographically important biota. Past investigations of the Deep Spring Formation at Mt. Dunfee, Nevada, explored the highly diverse microbialite reefs consisting of a wide range of stromatolite morphologies which exerted significant control on local sedimentation and topography. Early investigations also documented the biomineralizing metazoan Cloudina (an Ediacaran index fossil). However, recent exploration of the area has resulted in the discovery of several new metazoan fossil communities consisting of a diverse assemblage of Ediacaran soft-tissue tubicolous vermiforms (tube fossils) similar to Cloudina. The …

What Martian Meteorites Reveal About The Interior And Surface Of Mars, Arya Udry, G. H. Howarth, C. D.K. Herd, J. M.D. Day, T. J. Lapen, J. Filiberto

Geoscience Faculty Research

Martian meteorites are the only direct samples from Mars, thus far. Currently, there are a total of 262 individual samples originating from at least 11 ejection events. Geochemical analyses, through techniques that are also used on terrestrial rocks, provide fundamental insights into the bulk composition, differentiation and evolution, mantle heterogeneity, and role of secondary processes, such as aqueous alteration and shock, on Mars. Martian meteorites display a wide range in mineralogy and chemistry, but are predominantly basaltic in composition. Over the past 6 years, the number of martian meteorites recovered has almost doubled allowing for studies that evaluate these meteorites …

Xenon Iron Oxides Predicted As Potential Xe Hosts In Earth’S Lower Mantle, Feng Peng, Xianqi Song, Chang Liu, Quan Li, Maosheng Miao, Changfeng Chen, Yanming Ma

Physics & Astronomy Faculty Research

An enduring geological mystery concerns the missing xenon problem, referring to the abnormally low concentration of xenon compared to other noble gases in Earth’s atmosphere. Identifying mantle minerals that can capture and stabilize xenon has been a great challenge in materials physics and xenon chemistry. Here, using an advanced crystal structure search algorithm in conjunction with first-principles calculations we find reactions of xenon with recently discovered iron peroxide FeO2, forming robust xenon-iron oxides Xe2FeO2 and XeFe3O6 with significant Xe-O bonding in a wide range of pressure-temperature conditions corresponding to vast regions in Earth’s lower mantle. Calculated mass density and sound …

Investigation Of The Interaction Of Gadolinium With Several Organic Ligands And Humic Acid By Ligand Competition Using 4-(2-Pyridylazo)-Resorcinol (Par), Spencer Steinberg, Vernon Hodge, Luis Becerra-Hernandez

Chemistry and Biochemistry Faculty Research

Gd3+ forms a strongly colored complex with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solutions. We characterized the Gd3+-PAR complex in order to use it as a probe of Gd3+ speciation in the presence of environmentally relevant ligands. The formation of the Gd3+-PAR complex was investigated from pH 5 to 8 in the presence of excess PAR. The absorbance of the Gd3+-PAR complex dramatically increased from pH 5 to 8 and application of the method of continuous variation indicates that the complex was primarily 1:2 Gd(PAR)2 at pH 8. Stability constants for Gd3+ with other ligands can be quantified by competitive displacement of …

Evidence For Sodium-Rich Alkaline Water In The Tagish Lake Parent Body And Implications For Amino Acid Synthesis And Racemization, Lee F. White, Kimberly T. Tait, Brian Langelier, Elizabeth A. Lymer, Ana Černok, Tanya V. Kizovski, Chi Ma, Oliver Tschauner, Richard I. Nicklin

Geoscience Faculty Research

Understanding the timing and mechanisms of amino acid synthesis and racemization on asteroidal parent bodies is key to demonstrating how amino acids evolved to be mostly left-handed in living organisms on Earth. It has been postulated that racemization can occur rapidly dependent on several factors, including the pH of the aqueous solution. Here, we conduct nanoscale geochemical analysis of a framboidal magnetite grain within the Tagish Lake carbonaceous chondrite to demonstrate that the interlocking crystal arrangement formed within a sodium-rich, alkaline fluid environment. Notably, we report on the discovery of Na-enriched subgrain boundaries and nanometer-scale Ca and Mg layers surrounding …

Analysis Of Cryptotephra At Whitney Mesa Nature Preserve, Henderson, Nevada, Alex Newsom

Calvert Undergraduate Research Awards

Advanced Undergraduate Winner

Cryptotephra (small volcanic shards ranging 20-80 microns in size) were discovered within Unit X of the Las Vegas Formation at Whitney Mesa Nature Preserve, Henderson, Nevada. Cryptotephra are deposited soon after a volcanic eruption and can be used as a dating tool to create narrow time constraints for surrounding sediments. Cryptotephra have many applications but are mainly useful as a dating tool. Their study has important implications for the understanding of the timing of palaeoclimatological and paleoenvironmental events as well as for archaeological studies to date important events in human history.

The Whitney Mesa cryptotephra were correlated …

Thermal Analysis, Compressibility, And Decomposition Of Synthetic Bastnäsite-(La) To Lanthanum Oxyfluoride, Richard L. Rowland, Barbara Lavina, Kathleen E. Vander Kadeen, Lisa R. Danielson, Pamela C. Burnely

Geoscience Faculty Research

Understanding basic material properties of rare earth element (REE) bearing minerals such as their phase stability and equations of state can assist in understanding how economically viable deposits might form. Bastnäsite is the most commonly mined REE bearing mineral. We synthesized the lanthanum-fluoride end member, bastnäsite-(La) (LaCO3F), and investigated its thermal behavior and decomposition products from 298 K to 1173 K under ambient pressure conditions through thermogravimetric analysis, differential scanning calorimetry, evolved gas analysis, and high temperature powder X-ray diffraction. We also investigated the compressibility of bastnäsite-(La) via single crystal X-ray diffraction in diamond anvil cells at an ambient temperature …

Chemostratigraphic Correlations Across The First Major Trilobite Extinction And Faunal Turnovers Between Laurentia And South China, Jih-Pai Lin, Frederick A. Sunberg, Ganqing Jiang, Isabel P. Montanez, Thomas Wotte

Geoscience Faculty Research

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower–middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2–Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of the Miaolingian …

A New Plumbing System Framework For Mantle Plume-Related Continental Large Igneous Provinces And Their Mafic-Ultramafic Intrusions, Richard E. Ernst, Dustin A. Liikane, Simon M. Jowitt, K. L. Buchan, J. A. Blanchard

Geoscience Faculty Research

The magmatic components of continental Large Igneous Provinces (LIPs) include flood basalts and their plumbing system of giant mafic dyke swarms (radiating, linear, and the recently discovered circumferential type), mafic sill provinces, a lower crustal magmatic underplate, mafic-ultramafic (M–UM) intrusions, associated silicic magmatism, and associated carbonatites and kimberlites. This paper proposes a new plumbing system framework for mantle plume-related continental LIPs that incorporates all of these components, and provides a context for addressing key thematic aspects such as tracking magma batches “upstream” and “downstream” and their geochemical evolution, assessing the setting of M-UM intrusions and their economic potential, interpreting deep …