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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 19 recordsLinked to original sources
USGS1979

Earthquake studies on Canada’s west coast; Pacific Geoscience Centre

On a global scale, Canada's west coast lies within the zone of a seismicity that stretches around the Pacific Ocean. In plate tectonic terms, it is dominated by the same right-lateral shearing between the Pacific and American plates that is responsible for the seismicity of California. However, in southern British Columbia the interaction is further complicated. Between the San Andreas fault in California and the Queen Charlotte fault off British Columbia, the Pacific and American plates are separated by the small independent Juan de Fuca plate system. This is spreading away from the Pacific plate and converging with the margin of the Pacific Northwest. The resulting Cascade volcanic chain and its extension into southern British Columbia are the topograhic expression of its subduction.

Pacific coast↗
USGS2009

International year of planet earth 7. Oceans, submarine land-slides and consequent tsunamis in Canada

Canada has the longest coastline and largest continental margin of any nation in the World. As a result, it is more likely than other nations to experience marine geohazards such as submarine landslides and consequent tsunamis. Coastal landslides represent a specific threat because of their possible proximity to societal infrastructure and high tsunami potential; they occur without warning and with little time lag between failure and tsunami impact. Continental margin landslides are common in the geologic record but rare on human timescales. Some ancient submarine landslides are massive but more recent events indicate that even relatively small slides on continental margins can generate devastating tsunamis. Tsunami impact can occur hundreds of km away from the source event, and with less than 2 hours warning. Identification of high-potential submarine landslide regions, combined with an understanding of landslide and tsunami processes and sophisticated tsunami propagation models, are required to identify areas at high risk of impact.

Geoscience Canada↗
USGS2025

Critical Minerals in Ores (CMiO) database

Critical minerals are commodities essential to modern industrial and strategic technologies and are highly vulnerable to supply chain disruption. The Critical Minerals Mapping Initiative (CMMI) is a collaboration among the U.S. Geological Survey (USGS), the Geological Survey of Canada, and Geoscience Australia that aims to deepen global understanding of where critical minerals are located. A key output of this initiative is the Critical Minerals in Ores (CMiO) database that is advancing our collective understanding of critical minerals distributions. For instance, publicly available data on the concentrations of many critical minerals are sparse because these commodities can only be produced in small, yet essential, quantities compared to the primary commodities like copper and zinc. The CMiO database helps bridge this gap by offering high-quality, multielement geochemical data from a wide variety of critical mineral-bearing deposits around the world. Importantly, it uses a novel consensus deposit environment, group, and type classification scheme developed by the agencies that allows comparisons among ore deposits from different regions. The CMiO database contains geochemical data for more than 20,000 samples from more than 100 deposit types comprising 10 deposit environments.

Fact Sheet↗
USGS2016

Climate change and future fire regimes: Examples from California

Climate and weather have long been noted as playing key roles in wildfire activity, and global warming is expected to exacerbate fire impacts on natural and urban ecosystems. Predicting future fire regimes requires an understanding of how temperature and precipitation interact to control fire activity. Inevitably this requires historical analyses that relate annual burning to climate variation. Fuel structure plays a critical role in determining which climatic parameters are most influential on fire activity, and here, by focusing on the diversity of ecosystems in California, we illustrate some principles that need to be recognized in predicting future fire regimes. Spatial scale of analysis is important in that large heterogeneous landscapes may not fully capture accurate relationships between climate and fires. Within climatically homogeneous subregions, montane forested landscapes show strong relationships between annual fluctuations in temperature and precipitation with area burned; however, this is strongly seasonal dependent; e.g., winter temperatures have very little or no effect but spring and summer temperatures are critical. Climate models that predict future seasonal temperature changes are needed to improve fire regime projections. Climate does not appear to be a major determinant of fire activity on all landscapes. Lower elevations and lower latitudes show little or no increase in fire activity with hotter and drier conditions. On these landscapes climate is not usually limiting to fires but these vegetation types are ignition-limited. Moreover, because they are closely juxtaposed with human habitations, fire regimes are more strongly controlled by other direct anthropogenic impacts. Predicting future fire regimes is not rocket science; it is far more complicated than that. Climate change is not relevant to some landscapes, but where climate is relevant, the relationship will change due to direct climate effects on vegetation trajectories, as well as by feedback processes of fire effects on vegetation distribution, plus policy changes in how we manage ecosystems.

Geoscience Canada↗
USGS1990

Results of seismological monitoring in the Cascade Range 1962-1989: earthquakes, eruptions, avalanches and other curiosities

Modern monitoring of seismic activity at Cascade Range volcanoes began at Longmire on Mount Rainier in 1958. Since then, there has been an expansion of the regional seismic networks in Washington, northern Oregon and northern California. Now, the Cascade Range from Lassen Peak to Mount Shasta in the south and Newberry Volcano to Mount Baker in the north is being monitored for earthquakes as small as magnitude 2.0, and many of the stratovolcanoes are monitored for non-earthquake seismic activity. This monitoring has yielded three major observations. First, tectonic earthquakes are concentrated in two segments of the Cascade Range between Mount Rainier and Mount Hood and between Mount Shasta and Lassen Peak, whereas little seismicity occurs between Mount Hood and Mount Shasta. Second, the volcanic activity and associated phenomena at Mount St. Helens have produced intense and widely varied seismicity. And third, at the northern stratovolcanoes, signals generated by surficial events such as debris flows, icequakes, steam emissions, rockfalls and icefalls are seismically recorded. Such records have been used to alert authorities of dangerous events in progress. -Authors

Geoscience Canada↗
USGS1990

Patterns of volcanism in the Cascade Arc during the past 15 000 years

About 110 well-dated and 70 poorly dated eruptive periods less than 15 000 years old at individual volcanoes in the Cascade Arc constitute a data set for identifying spatial and temporal patterns of eruptive activity. Key features of the record include: 1) the mean frequency of eruptive periods during the past 4000 years is approximately two per century; however, the variance about the mean may be large; 2) at most major centres, episodes of activity lasting several thousand years are defined by groups of eruptive periods separated by apparent dormant intervals of roughly similar duration, 3) arc-wide clustering of eruptive activity may exist at 0-4 ka, 6-8 ka, and 10-14 ka. Such clustering would be remarkable in light of significant along-arc changes in crustal structure, stress field, and subduction-zone geometry. -Author

Geoscience Canada↗
USGS1996

Porphyry deposits of the Canadian Cordillera

Porphyry deposits are intrusion-related, large tonnage low grade mineral deposits with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis of these deposits is related to the emplacement of intermediate to felsic, hypabyssal, generally porphyritic intrusions that are commonly formed at convergent plate margins. Porphyry deposits of the Canadian Cordillera occur in association with two distinctive intrusive suites: calc-alkalic and alkalic. In the Canadian Cordillera, these deposits formed during two separate time periods: Late Triassic to Middle Jurassic (early Mesozoic), and Late Cretaceous to Eocene (Mesozoic-Cenozoic). Deposits of the early Mesozoic period occur in at least three different arc terranes (Wrangellia, Stikinia and Quesnellia) with a single deposit occurring in the oceanic assemblage of the Cache Creek terrane. These terranes were located outboard from continental North America during formation of most of their contained early Mesozoic porphyry deposits. Some of the deposits of this early period may have been emplaced during terrane collisions. Metal assemblages in deposits of the calc-alkalic suite include Mo-Cu (Brenda), Cu-Mo (Highland Valley, Gibraltar), Cu-Mo-Au-Ag (Island Copper, Schaft Creek) and Cu-Au (Kemess, Kerr).The alkalic suite deposits are characterized by a Cu-Au assemblage (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver is recovered from calc-alkalic and alkalic porphyry copper mining operations, silver data are seldom included in the published reserve figures. Those available are in the range of 1-2 grams per tonne (g??t-1). Alkalic suite deposits are restricted to the early Mesozoic and display distinctive petrology, alteration and mineralization that suggest a similar tectonic setting for both Quesnellia and Stikinia in Early Jurassic time. The younger deposits, late Mesozoic to Cenozoic in age, formed in an intracontinental setting, after the outboard host arc and related terranes accreted to the western margin of North America. These deposits are interpreted to occur in continental arc settings, and individual deposits are hosted by a variety of older country rocks. These younger deposits also show a spectrum of metal associations: Cu-Mo (Huckleberry, Berg), Cu-Au (-Mo) (Bell, Granisle, Fish Lake, Casino), Mo (Endako, Boss Mountain, Kit-sault, Quartz Hill), Mo-W (Logtung), Au-W (Dublin Gulch) and Au (Ft. Knox). There may be a continuum between Mo, Mo-W, Au-Mo-W and Au deposits. The distribution and timing of these post-accretion deposits likely reflect major crustal structures and subduction geometry. Cordilleran porphyry metallic deposits show the full range of morphological and depth relationships found in porphyry deposits worldwide. In addition, the Cordillera contains numerous alkalic suite deposits, which are rare worldwide: the unusual, possibly syntectonic Gibraltar deposit; and end-member gold-rich granite-hosted deposits, such as Ft. Knox (Alaska).

Geoscience Canada↗
USGS1990

Overview of the effects and influence of the activity of Mount St. Helens in the 1980s

The cataclysmic eruption of Mount St. Helens on May 18, 1980, made an enormous impact on the science of volcanology. The eruption was in daylight in clear weather, which provided an unprecedented opportunity to investigate relations among observations, products, and effects of a large explosive eruption. The May 18 events and subsequent activity stimulated perhaps the most intensive studies ever made at an active composite volcano, leading to greatly enhanced insights into both geologic and hydrologic processes operative in explosive volcanism. The eruption also disrupted much of the social and economic fabric of the Pacific Northwest. Volcanologists were called upon to explain the activity, in layman's terms, to government and corporate officials, the news media, schools, and the public at large. People eventually learned to live with the volcano and its uncertainties, and volcanologists better learned their role in helping society deal with a major natural disaster. Difficulties encountered at volcanic crises elsewhere in the world in the 1980s demonstrate that these are hard lessons. In future years, a paramount challenge for scientists will be to help society apply what has been learned at Mount St. Helens to crises both nearby and far away.

Washington↗
USGS2021

Data-driven prospectivity modelling of sediment-hosted mineral systems

Mississippi Valley-type (MVT) and clastic-dominated (CD) deposits are important sources for Zn, Pb, Ag, and Cd as well as the critical elements Ga, Ge, In, and Sb. However, mapping the drivers, sources, pathways, and traps of MVT and CD deposits within the much larger and mostly unmineralized sedimentary basins remain some of the least understood aspects of these mineral systems. Herein we address those knowledge gaps by integrating public geoscience datasets from Canada, the United States of America, and Australia using a discrete global grid system to map the continent-scale footprints of MVT and CD deposits.

Conference Paper↗
USGS2020

International geoscience collaboration to support critical mineral discovery

The importance of critical minerals and the need to expand and diversify critical mineral supply chains has been endorsed by the Federal governments of Australia, Canada, and the United States. The geoscience organizations of Geoscience Australia, the Geological Survey of Canada and the U.S. Geological Survey have created the Critical Minerals Mapping Initiative to build a diversified critical minerals industry in Australia, Canada, and the United States by developing a better understanding of known critical mineral resources, determining geologic controls on critical mineral distribution for deposits currently producing byproducts, identifying new sources of supply through critical mineral potential mapping and quantitative mineral assessments, and promoting critical mineral discovery in all three countries.

Fact Sheet↗
USGS2020

North American Commission on Stratigraphic Nomenclature Note 70: Records of the Stratigraphic Commission 2014-2017

NACSN (North American Commission on Stratigraphic Nomenclature) Note 70 is a summary of the activities of the Commission from October 2014-October 2017. This note is condensed from the minutes of the 69th through the 72nd meetings of the NACSN held in conjunction with the Annual Meetings of the Geological Society of America. The 69th meeting of the NACSN was held October 20, 2014, in Vancouver, British Columbia; the 70th meeting on November 2, 2015, in Baltimore, Maryland; the 71st meeting on September 26, 2016, in Denver, Colorado; and the 72nd meeting on October 23, 2017, in Seattle, Washington. Members of the NACSN who served as officers during the period 2014-2017 serve as co-authors of this note and are listed with their roles in Appendix A. The mission of the NACSN is to develop statements of stratigraphic principles, recommend procedures applicable to the classification of nomenclature of stratigraphic units, review problems in classifying and naming stratigraphic and related units, and formulate expressions of judgement on these matters. Commissioners of the NACSN represent various geoscience professional organizations from Canada, Mexico, and the United States who have an interest in maintaining a stable stratigraphic nomenclature. Commissioners and their constituencies for 2014-2017 are listed in Appendix B.

Stratigraphy↗
USGS2013

Assessment of undiscovered conventional oil and gas resources of the Western Canada Sedimentary Basin, Canada, 2012

The U.S. Geological Survey recently completed a geoscience-based assessment of undiscovered oil and gas resources of provinces within the Western Canada Sedimentary Basin. The Western Canada Sedimentary Basin primarily comprises the (1) Alberta Basin Province of Alberta, eastern British Columbia, and the southwestern Northwest Territories; (2) the Williston Basin Province of Saskatchewan, southeastern Alberta, and southern Manitoba; and (3) the Rocky Mountain Deformed Belt Province of western Alberta and eastern British Columbia. This report is part of the U.S. Geological Survey World Petroleum Resources Project assessment of priority geologic provinces of the world. The assessment was based on geoscience elements that define a total petroleum system (TPS) and associated assessment unit(s). These elements include petroleum source rocks (geochemical properties and petroleum generation, migration, and accumulation), reservoir description (reservoir presence, type, and quality), and petroleum traps (trap and seal types, and timing of trap and seal formation relative to petroleum migration). Using this framework, the Elk Point-Woodbend Composite TPS, Exshaw-Fernie-Mannville Composite TPS, and Middle through Upper Cretaceous Composite TPS were defined, and four conventional assessment units within the total petroleum systems were quantitatively assessed for undiscovered resources in the Western Canada Sedimentary Basin.

Fact Sheet↗
USGS2021

Toward an effective global green economy: The Critical Minerals Mapping Initiative (CMMI)

Global population growth, economic development and the accelerating pace of technological innovation are driving increased demand for non-fuel mineral commodities that are vital for emerging and low-carbon technologies. Examples of such commodities include cobalt and graphite for rechargeable batteries, tellurium in thin-film solar photovoltaics and rare earth elements (REE) in permanent magnets, electronics and medical technologies. These commodities are known as critical elements and/or minerals (collectively referred to as critical minerals), with the term critical used to define not only their importance for new technologies, but also their demand and vulnerability to supply disruption. The demand for critical minerals is likely to continue to grow, but supply is not assured. Therefore, national strategies in Australia, Canada, United States and elsewhere (e.g. Europe: Wittenberg et al. 2021) are being developed to encourage exploration and production, including resolving the geological processes responsible for their enrichrichment into viable ore deposits. In 2019, Geoscience Australia (GA), the Geological Survey of Canada (GSC) and the United States Geological Survey (USGS) formed the Critical Minerals Mapping Initiative (CMMI) to undertake research to develop a better understanding of critical mineral resources in known deposits, determine the geological controls on critical mineral distribution for deposits currently producing by-products, and identify new sources of supply through mineral prospectivity mapping and resource assessment.

SGA News↗
USGS2022

Data-driven prospectivity modelling of sediment-hosted Zn-Pb mineral systems and their critical raw materials

Demand for critical raw materials is expected to accelerate over the next few decades due to continued population growth and the shifting consumption patterns of the global economy. Sedimentary basins are important sources for critical raw materials and new discoveries of sediment–hosted Mississippi Valley–type (MVT) and/or clastic–dominated (CD) Zn–Pb deposits are likely required to mitigate future supply chain disruptions for Zn, Pb, Ag, Cd, Ga, Ge, Sb, and In. Herein we integrate public geoscience datasets using a discrete global grid to system to model the mineral potential for MVT and CD deposits across Canada, the United States of America, and Australia. Statistical analysis of the model results demonstrates that surface–wave tomography and derivative products from satellite gravity datasets can be used to map the most favourable paleo–tectonic settings of MVT and CD deposits inboard of orogenic belts and at the rifted edges of cratonic lithosphere, respectively. Basin development at pre–existing crustal boundaries was likely important for maintaining the low geothermal–gradients that are favourable for metal transport and generating the crustal fluid pathways that were reactivated during ore–formation, as suggested by the statistical association of both sediment–hosted mineral deposit types with the edges of upward–continued gravity and long–wavelength magnetic anomalies. Multivariate statistical analysis demonstrates that the most prospective combination of these geophysical datasets varies for each geological region and deposit type. We further demonstrate that maximum and minimum geological ages, coupled with Phanerozoic paleogeographic reconstructions, represent mappable proxies for the availability of oxidized, brine–generating regions that are the most likely source of ore–forming fluids (e.g., low– to mid–latitude carbonate platforms and evaporites). Ore deposition was likely controlled by interaction between oxidized, low–temperature brines and sulfidic and/or carbonaceous rocks, which, in some cases, can be mapped at the exposed surface or identified using the available rock descriptions. Baseline weights–of–evidence models are based on regional geophysics and are the least impacted by missing surface information but yield relatively poor results, as demonstrated by the low area–under–the–curve (AUC) for the spatially independent test set on the success–rate plot (AUC = 0.787 for MVT and AUC = 0.870 for CD). Model performance can be improved by: (1) using advanced methods that were trained and validated during a series of semi–automated machine learning competitions; and/or (2) incorporating geological and geophysical datasets that are proxies for each component of the mineral system. The best–performing gradient boosting machine models yield higher AUC for the test set (AUC = 0.983 for MVT and AUC = 0.991 for CD) and reduce the search space by >94%. The model results highlight the potential benefits of mapping sediment–hosted mineral systems at continental scale to improve mineral exploration targeting for critical raw materials.

Ore Geology Reviews↗
USGS2023

Applications of natural language processing to geoscience text data and prospectivity modelling

Geological maps are powerful models for visualizing the complex distribution of rock types through space and time. However, the descriptive information that forms the basis for a preferred map interpretation is typically stored in geological map databases as unstructured text data that are difficult to use in practice. Herein we apply natural language processing (NLP) to geoscientific text data from Canada, the U.S., and Australia to address that knowledge gap. First, rock descriptions, geological ages, lithostratigraphic and lithodemic information, and other long-form text data are translated to numerical vectors, i.e., a word embedding, using a geoscience language model. Network analysis of word associations, nearest neighbors, and principal component analysis are then used to extract meaningful semantic relationships between rock types. We further demonstrate using simple Naive Bayes classifiers and the area under receiver operating characteristics plots (AUC) how word vectors can be used to: (1) predict the locations of “pegmatitic” (AUC = 0.962) and “alkalic” (AUC = 0.938) rocks; (2) predict mineral potential for Mississippi-Valley-type (AUC = 0.868) and clastic-dominated (AUC = 0.809) Zn-Pb deposits; and (3) search geoscientific text data for analogues of the giant Mount Isa clastic-dominated Zn-Pb deposit using the cosine similarities between word vectors. This form of semantic search is a promising NLP approach for assessing mineral potential with limited training data. Overall, the results highlight how geoscience language models and NLP can be used to extract new knowledge from unstructured text data and reduce the mineral exploration search space for critical raw materials.

Natural Resources Research↗
USGS2006

The quest for the perfect gravity anomaly: Part 2 - Mass effects and anomaly inversion

Gravity anomalies have become an important tool for geologic studies since the widespread use of high-precision gravimeters after the Second World War. More recently the development of instrumentation for airborne gravity observations, procedures for acquiring data from satellite platforms, the readily available Global Positioning System for precise vertical and horizontal control, improved global data bases, and enhancement of computational hardware and software have accelerated the use of the gravity method. As a result, efforts are being made to improve the gravity databases that are made available to the geoscience community by broadening their observational holdings and increasing the accuracy and precision of the included data. Currently the North American Gravity Database as well as the individual databases of Canada, Mexico, and the United States of America are being revised using new formats and standards. The objective of this paper is to describe the use of the revised standards for gravity data processing and modeling and there impact on geological interpretations. ?? 2005 Society of Exploration Geophysicists.

SEG Technical Program Expanded Abstracts↗
USGS2011

Surficial geology and benthic habitat of the German Bank seabed, Scotian Shelf, Canada

To provide the scientific context for management of a newly opened scallop fishing ground, surficial geology and benthic habitats were mapped on German Bank on the southern Scotian Shelf off Atlantic Canada. To provide a seamless regional dataset, multibeam sonar surveys covered 5320 sqaure kilometres of the bank in water depths of 30–250 m and provided 5 m horizontal resolution bathymetry and backscatter strength. Geoscience data included high-resolution geophysical profiles (seismic reflection and sidescan sonar) and seabed sediment samples. Geological interpretation and is overlain in places by glacial and postglacial sediment. Biological data included seafloor video transects and photographs from which 127 taxa of visible megabenthos were identified. Trawl bycatch data were obtained from government annual research surveys. Statistical analysis of revealed that bedrock is exposed at the seafloor on much of German Bankthese two datasets and a suite of oceanographic environmental variables demonstrated that significantly different fauna exist on bedrock, glacial sediment and postglacial sediment.

German Bank seabed, Scotian Shelf↗