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Travis L. Hudson

Publications and source records attributed to Travis L. Hudson.

14 recordsLinked to original sources
USGS2026

Upper Triassic igneous rocks of the southern Kenai Peninsula, Alaska – Prelude to Early Jurassic subduction along the western Wrangellia composite terrane margin

New U–Pb zircon geochronology identifies a latest Triassic (ca 214–201 Ma) igneous suite of tuff, hypabyssal dikes, and a pluton on the southern Kenai Peninsula, Alaska. The igneous suite was emplaced within Upper Triassic sedimentary rocks along the southern margin of Western Wrangellia, the western-most fragment of the Wrangellia composite terrane. The igneous rocks range from mafic (50.6% SiO 2 ) to felsic (78.3% SiO 2 ), characteristically have less than 1.55% K 2 O, and generally have low trace element abundances. The tonalitic and trondhjemitic magmas were largely sourced in mafic-rich lower crust and incompletely assimilated quartz and other mineral xenocrysts are common. Fractionation involving plagioclase and amphibole is indicated for some magmas and composite intrusions and igneous xenoliths indicate magma mixing was possible. Paleozoic and Precambrian inherited zircons and initial 87 Sr/ 86 Sr (0.704103–0.705609) and 143 Nd/ 144 Nd (0.512396–0.512777) ratios indicate that the Western Wrangellia crustal sources are heterogeneous and contain sialic components. The latest Triassic magmatism reflects processes that preceded Early Jurassic subduction along the Wrangellia composite terrane and Pacific Ocean plate boundary. These processes involved heating and melting of mantle lithosphere and lower crust as mantle instabilities accompanied the breaking of the plate boundary linkages. The Late Triassic transition to subduction along the Wrangellia composite terrane margin coincided with the transition to subduction cessation in the Late Triassic arcs of the western Intermontane terranes of Canada. The shift to subduction along the outboard Wrangellia composite terrane margin marks the beginning of the Pacific Ocean–Cordillera plate interactions that came to dominate the tectonic evolution of the northern Cordillera from the Early Jurassic to today.

Alaska↗
USGS2023

The Lower Cretaceous sequence of western Alaska – demise of the Koyukuk terrane?

Lower Cretaceous marine sedimentary rocks, deposited in shallow shelf and basin settings and unconformity-bound, are well exposed in southwest Alaska. Collections of Early Cretaceous fossils from across western Alaska show that similar and coeval Lower Cretaceous clastic rocks are widely distributed though only locally exposed. Volcanic rocks become an important part of the Lower Cretaceous sequence in the Yukon-Koyukuk basin where they have been interpreted to represent a mobile intra-oceanic island arc, the Koyukuk terrane, that collided with Arctic Alaska to form the Brooks Range orogen. The volcanic rocks are chemically unlike Aleutian arc rocks but share compositional characteristics with spatially related, mid-Cretaceous alkaline intrusive rocks. The volcanic-bearing sequence was also deposited on an angular unconformity, includes both shallow shelf and basin depositional settings, and is unconformably overlain by mid-Cretaceous clastic rocks. The volcanic rocks are therefore considered part of the Lower Cretaceous sequence now identified across western Alaska. In this interpretation, the Lower Cretaceous volcanic rocks are an initial expression of the mid-Cretaceous tectonic regime that included extensional exhumation and subsidence, crustal and upper mantle melting, and high temperature metamorphism in the hinterland of the Brooks Range orogen. The Cretaceous heating that led to hinterland crust and upper mantle change may have been caused by deep mantle disturbances in a post-subduction setting. This interpretation has implications for the timing of contractional orogenesis, the location and nature of the related continental borderland, and the tectonic setting for development of the Anguyucham and related oceanic terranes.

Alaska↗
USGS2010

Reconnaissance study of the Taylor Mountains pluton, southwestern Alaska

The Taylor Mountains pluton is a Late Cretaceous to early Tertiary (median age 65 + or ? 2 Ma) epizonal, composite biotite granite stock located about 235 km (145 mi) northeast of Dillingham in southwestern Alaska. This 30 km2 (12 mi2) pluton has sharp and discordant contacts with hornfels that developed in Upper Cretaceous clastic sedimentary rocks of the Kuskokwim Group. The three intrusive phases in the Taylor Mountains pluton, in order of emplacement, are (1) porphyritic granite containing large K-feldspar phenocrysts in a coarse-grained groundmass, (2) porphyritic granite containing large K-feldspar and smaller, but still coarse, plagioclase, quartz, and biotite phenocrysts in a fine-grained groundmass, and (3) fine-grained, leucocratic, equigranular granite. The porphyritic granites have different emplacement histories, but similar compositions; averages are 69.43 percent SiO2, 1.62 percent CaO, 5.23 percent FeO+MgO, 3.11 percent Na2O, and 4.50 percent K2O. The fine-grained, equigranular granite is distinctly felsic compared to porphyritic granite; it averages 75.3 percent SiO2, 0.49 percent CaO, 1.52 percent FeO+MgO, 3.31 percent Na2O, and 4.87 percent K2O. Many trace elements including Ni, Cr, Sc, V, Ba, Sr, Zr, Y, Nb, La, Ce, Th, and Nd are strongly depleted in fine-grained equigranular granite. Trace elements are not highly enriched in any of the granites. Known hydrothermal alteration is limited to one tourmaline-quartz replacement zone in porphyritic granite. Mineral deposits in the Taylor Mountains area are primarily placer gold (plus wolframite, cassiterite, and cinnabar); sources for these likely include scattered veins in hornfels peripheral to the Taylor Mountain pluton. The granite magmas that formed the Taylor Mountains pluton are thought to represent melted continental crust that possibly formed in response to high heat flow in the waning stage of Late Cretaceous subduction beneath interior Alaska.

Professional Paper↗
USGS2006

Major- and Trace-Element Concentrations in Rock Samples Collected in 2005 from the Taylor Mountains 1:250,000-scale Quadrangle, Alaska

The data consist of major- and minor-element concentrations for rock samples collected during 2005 by the U.S. Geological Survey. Samples were analyzed by fire assay (Au, Pd, Pt), cold vapor atomic absorption spectroscopy (Hg), and the inductively coupled plasma mass spectrometry (ICPMS) 10 and 42 element methods. For details of sample preparation and analytical techniques see USGS Open File Report 02-0223 (Analytical methods for chemical analysis of geologic and other materials, U.S. Geological Survey), available at .

Open-File Report↗
USGS2003

Preliminary geologic map of the northeast Dillingham quadrangle (D-1, D-2, C-1, and C-2), Alaska

Open-File Report 03-105 contains a digital geologic map database for the northeast part of the Dillingham 1:250,000-scale quadrangle, specifically the D-1, D-2, C-1, and C-2 1:63,360-scale map sheets. The report includes: A Postscript file showing the geologic map on a topographic and land-grid base, and containing a Correlation of Map Units diagram (CMU), and a List of Map Units. (Note the size of the map when printed at publication scale (1:100,000) is 30 by 24 inches (76 by 61 cm). A PDF document providing Introductory text, Description of Map Units (DMU), References, and a table of radiometric ages. A collection of ARC/INFO (http://www.esri.com, Environmental Systems Research Institute) version 7.2.1 coverages (as export files) of the elements of the geologic map, including: a. Network coverage containing the geologic polygons, contacts, and faults, b. Annotation coverage containing the geologic unit labels and leaders, c. Point coverage containing the radiometric age sample localities, d. Template files containing the lookup table structure used to produce the map. Data to populate the template files is provided in comma-separated value (.csv) text files as follows: napkey.csv plutonkey.csv geoline.csv e. Network coverage containing the Correlation of Map Units (CMU) for the map. Portable Document Format (.pdf) files consisting of: a. Introductory text, Description of Map Units (DMU), References, and a table of radiometric ages for the map. b. A graphic of the map as in the Postscript file above. FGDC compliant metadata for the digital data files (coverages). The Correlation of Map Units and Description of Map Units are in a format similar to that of the USGS Geologic Investigations Series (I-series) maps but have not been edited to comply with I-map standards. Even though this is an Open-File Report and includes the standard USGS Open-File disclaimer, the report closely adheres to the Stratigraphic Nomenclature of the U.S. Geological Survey. ARC/INFO symbolsets (shade and line) as used for these maps have been made available elsewhere as part of Geologic map of Central (Interior) Alaska, published as a USGS Open-File Report (Wilson and others, 1998, http://geopubs.wr.usgs.gov/open-file/of98-133-a/). This product does not include the digital topographic base or land-grid files used to produce the map, nor does it include the AML and related ancillary key and other files used to assemble the components of the map. A Postscript file showing the geologic map on a topographic and land-grid base, and containing a Correlation of Map Units diagram (CMU), and a List of Map Units. (Note the size of the map when printed at publication scale (1:100,000) is 30 by 24 inches (76 by 61 cm). A PDF document providing Introductory text, Description of Map Units (DMU), References, and a table of radiometric ages. A collection of ARC/INFO (http://www.esri.com, Environmental Systems Research Institute) version 7.2.1 coverages (as export files) of the elements of the geologic map, including: a. Network coverage containing the geologic polygons, contacts, and faults, b. Annotation coverage containing the geologic unit labels and leaders, c. Point coverage containing the radiometric age sample localities, d. Template files containing the lookup table structure used to produce the map. Data to populate the template files is provided in comma-separated value (.csv) text files as follows: napkey.csv plutonkey.csv geoline.csv e. Network coverage containing the Correlation of Map Units (CMU) for the map. Portable Document Format (.pdf) files consisting of: a. Introductory text, Description of Map Units (DMU), References, and a table of radiometric ages for the map. b. A graphic of the map as in the Postscript file above. FGDC compliant metadata for the digital data files (coverages). The Correlation of Map Units and Description of Map Units are in a format similar to that of the USGS Geologic Investigations Series (I-series) maps but have not been edited to comply with I-map standards. Even though this is an Open-File Report and includes the standard USGS Open-File disclaimer, the report closely adheres to the Stratigraphic Nomenclature of the U.S. Geological Survey. ARC/INFO symbolsets (shade and line) as used for these maps have been made available elsewhere as part of Geologic map of Central (Interior) Alaska, published as a USGS Open-File Report (Wilson and others, 1998, http://geopubs.wr.usgs.gov/open-file/of98-133-a/). This product does not include the digital topographic base or land-grid files used to produce the map, nor does it include the AML and related ancillary key and other files used to assemble the components of the map.

Alaska↗
USGS2003

Alaska resource data file: McCarthy quadrangle

Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

Alaska↗
USGS2003

Alaska resource data file: Nabesna quadrangle

Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

Alaska↗
USGS2001

Pimienta-Tamabra(!)— A giant supercharged petroleum system in the southern Gulf of Mexico, onshore and offshore Mexico

Pimienta-Tamabra(!) is a giant supercharged petroleum system in the southern Gulf of Mexico with cumulative production and total reserves of 66.3 billion barrels of oil and 103.7 tcf of natural gas, or 83.6 billion barrels of oil equivalent (BOE). The effectiveness of this system results largely from the widespread distribution of good to excellent thermally mature, Upper Jurassic source rock underlying numerous stratigraphic and structural traps that contain excellent carbonate reservoirs. Expulsion of oil and gas as a supercritical fluid from Upper Jurassic source rock occurred when the thickness of overburden rock exceeded 5 km. This burial event started in the Eocene, culminated in the Miocene, and continues to a lesser extent today. The expelled hydrocarbons started migrating laterally and then upward as a gas-saturated 35-40° API oil with less than 1 wt.% sulfur and a gas-to-oil ratio (GOR) of 500-1000 ft 3 /BO. The generation-accumulation efficiency is about 6%.

southern Gulf of Mexico↗
USGS1999

Metal mining and the environment

The booklet, Metal Mining and the Environment, and the colorful companion poster offer new tools for raising awareness and understanding of the impact and issues surrounding metal mining and the environment. The 64-page full-color booklet contains a copy of the poster which includes a student activity on the back. This booklet and poster can help you: illustrate the importance of our natural and environmental resources; provide a geoscience perspective on metal mining and the environment; improve Earth science literacy; and increase student understandings of Earth resources and systems.

Book↗