GSN April Meeting—April 15—RSVP by April 13

GSN logoStudent Posters and Oral Presentations Night, Mackay School of Earth Sciences and Engineering

GSN Friday, APRIL 15, 2016 Membership Meeting
STUDENT POSTERS & ORAL PRESENTATIONS NIGHT
MACKAY SCHOOL OF EARTH SCIENCES & ENGINEERING

For dinner reservations, please e-mail gsn@gsnv.org or call Laura Ruud at 775-323-3500 by 5:00 p.m. on WEDNESDAY, APRIL 13TH
Social Hour and Poster Presentations begin @ 6:00 pm; Dinner @ 7:00 pm; Two Student Speakers to Follow @ 7:45 pm
Location:  RENO ELKS LODGE, 597 KUMLE LANE (across from the Convention Center)
DINNER COST—$25.00 per person (Reservation no-shows will be invoiced.)

Two Student Oral Presenters:  Chad Carlson and Steven Howell

“Enigmatic Walker Lane Dextral-Shear Accommodation: Paleomagnetically-Determined Vertical-Axis Rotation of Crustal Blocks between the Central Walker Lane and Sierra Nevada Frontal Fault System”
Chad W. Carlson, Nevada Bureau of Mines and Geology, University of Nevada, Reno
James E. Faulds, Nevada Bureau of Mines and Geology, University of Nevada, Reno
SPEAKER ABSTRACT: Located west of dextral fault systems of the central Walker Lane and east of the Sierra Nevada frontal-fault system is a region of north-striking normal faults and asymmetric basins, where geodetic studies define ~5 mm/yr of northwest-directed dextral strain. As this region is devoid of major strike-slip fault systems, how this strain is accommodated is poorly understood. To elucidate the long-term tectonic development of this region, paleomagnetic data from late Oligocene ash-flow tuffs are used to determine magnitudes of vertical-axis rotation of crustal blocks, as a potential mechanism for accommodation of dextral shear.
Paleomagnetic directions collected from multiple locations across the region define domains of vertical-axis rotation of varying magnitudes. Preliminary paleomagnetic data have identified low/no rotations within translating blocks of the central Walker Lane (Walker Lake domain), statistically-significant magnitudes of ~20-30° clockwise vertical-axis rotation west of central Walker Lane dextral faults, and >30° of clockwise rotation to the northwest in the northern Walker Lane (Carson domain). Boundaries between these domains, although potentially gradational, are relatively discrete and support a distinction of domains by style of faulting. Comparison of Oligocene ash-flow tuff rotation data to previously sampled Mio-Pliocene volcanics and present-day geodetically-derived rotation rates sup-port a late-Miocene initiation of dextral-shear accommodation in the region and suggest a decrease in rotation rates over time.

“Formation of Disseminated Epithermal Gold Ore at Round Mountain, Nevada”
Steven Howell, Center for Research in Economic Geology
John Muntean, Center for Research in Economic Geology, Nevada Bureau of Mines and Geology
SPEAKER (& POSTER) ABSTRACT: The Round Mountain gold deposit is a world-class bulk-minable low-sulfidation volcanic-hosted epithermal deposit with 20 million contained ounces of gold.  Research was aimed at better understanding how disseminated ore at Round Mountain formed.  Specifically alteration and the disseminated mineralization are documented at all scales within the poorly-welded unit of the Round Mountain tuff and distinct fluids pathways of the ore-forming hydrothermal fluids are identified.  Detailed logging, petrographic work, whole-rock geochemical assays and hyperspectral data indicate disseminated mineralization is associated with strong potassic alteration expressed geochemically by the metasomatic enrichment of potassium and depletion of sodium and calcium from drill-fan to mine-wide scales.  Several major upwelling zones are apparent in models of gold mineralization and mine-wide mass change models of major oxide elements derived from whole-rock geochemical assays.  Upwelling zones are largely controlled by a WNW structural fabric in underlying Paleozoic meta-sedimentary rock.  Multiple overprinting phases of concentric alteration assemblages consisting of inner silica-adularia, middle illite and outer smectite zones exist within the mineralized lower poorly-welded tuff.  Porosity and permeability de-crease with each overprinting hydrothermal event, and fluid pathways appear to constrict with each subsequent event, forming higher-grade cross-cutting tubular or vein-like structures.

STUDENT POSTER PRESENTATIONS
(Note from GSN: Posters we had by press time with more still being submitted!)

Name:  Justin B. Milliard
Poster Title:  “Preliminary Insights into Multi-Scale Fluid Pathway Controls from the Middle Miocene Northern Nevada Rift, North-Central, Nevada, USA”
Co-Author:  John L. Muntean

Name:  Carli Balogh
Poster Title:  “Tertiary Volcanic Rocks, Hydrothermal Alteration, and Epithermal Precious Metal Deposits of the  Patterson Mining District, Sweetwater Mountains, Lyon County, NV and Mono County, CA”
Co-Author: Peter Vikre

Name: Sergey A. Konyshev
Poster Title:  “Sedimentary Rock-hosted Gold Mineralization of the Stibnite District, Valley County, Idaho”
Advisor: John L. Muntean

Name: Elizabeth Benge
Poster Title:  “Pilot Study using Elemental Geochemistry as a Means of Discriminating Chert Stratigraphy in the Roberts Mountains Allochthon, Nevada”
Co-Author: Paula Noble

Name: Carolina Zamora
Poster Title (Tentative):  “Investigating the Cooling History of the Eastern Himalaya Greater Himalayan Rocks:  A 40Ar/39Ar and U-Pb Thermochronology Study from Eastern Bhutan”
Co-authors: Dr. Stacia Gordon (UNR), Dr. Sean Long (WSU) (more to be added)

Name:  Tyler Hill
Poster Title:  “Time-Space Relationships between Sediment-Hosted Gold Mineralization and Intrusion-Related Polymetallic Mineralization at Kinsley Mountain, NV”
Co-Authors: John Muntean, Moira Smith, and Robert Creaser

Name: Tracy Anderson
Poster Title:  “Testing Silver Mobility: An Investigation into Supergene Silver Enrichment at the Rochester Mine in  Pershing County, NV”
Advisor/Co-Author:  John Muntean

Name:  Holly McLachlan
Poster Title:  “Stratigraphy of the Soda Lake Geothermal Field, Fallon, NV”
Advisor/Co-Author:  Jim Faulds

Name: Robin Chacko
Poster Title:  “Magmatic-Tectonic Interactions: Implications for Seismic Hazard Assessment in the Central Walker Lane and Long Valley Caldera Regions”
Co-Authors: William Hammond, Geoffrey Blewitt, Jayne Bormann

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