Mid-holocene sector collapse at Mount Spurr Volcano, South-Central Alaska

2007 ◽  
Author(s):  
Christopher F. Waythomas
Keyword(s):  
Sector Collapse ◽  
South Central ◽  
Mount Spurr

Flank collapse at Mount Wrangell, Alaska, recorded by volcanic mass-flow deposits in the Copper River lowland

2002 ◽  
Vol 39 (8) ◽  
pp. 1257-1279 ◽  
Author(s):  
Christopher F Waythomas ◽  
Kristi L Wallace
Keyword(s):  
Debris Flow ◽  
Mass Flow ◽  
Volcanic Rocks ◽  
Debris Avalanche ◽  
Sector Collapse ◽  
Flow Forming ◽  
Flank Collapse ◽  
South Central ◽  
Flow Deposit ◽  
Facies Types

An areally extensive volcanic mass-flow deposit of Pleistocene age, known as the Chetaslina volcanic mass-flow deposit, is a prominent and visually striking deposit in the southeastern Copper River lowland of south-central Alaska. The mass-flow deposit consists of a diverse mixture of colorful, variably altered volcanic rocks, lahar deposits, glaciolacustrine diamicton, and till that record a major flank collapse on the southwest flank of Mount Wrangell. The deposit is well exposed near its presumed source, and thick, continuous, stratigraphic exposures have permitted us to study its sedimentary characteristics as a means of better understanding the origin, significance, and evolution of the deposit. Deposits of the Chetaslina volcanic mass flow in the Chetaslina River drainage are primary debris-avalanche deposits and consist of two principal facies types, a near-source block facies and a distal mixed facies. The block facies is composed entirely of block-supported, shattered and fractured blocks with individual blocks up to 40 m in diameter. The mixed facies consists of block-sized particles in a matrix of poorly sorted rock rubble, sand, and silt generated by the comminution of larger blocks. Deposits of the Chetaslina volcanic mass flow exposed along the Copper, Tonsina, and Chitina rivers are debris-flow deposits that evolved from the debris-avalanche component of the flow and from erosion and entrainment of local glacial and glaciolacustrine diamicton in the Copper River lowland. The debris-flow deposits were probably generated through mixing of the distal debris avalanche with the ancestral Copper River, or through breaching of a debris-avalanche dam across the ancestral river. The distribution of facies types and major-element chemistry of clasts in the deposit indicate that its source was an ancestral volcanic edifice, informally known as the Chetaslina vent, on the southwest side of Mount Wrangell. A major sector collapse of the Chetaslina vent initiated the Chetaslina volcanic mass flow forming a debris avalanche of about 4 km3 that subsequently transformed to a debris flow of unknown volume.

Seismicity and stress in the vicinity of Mount Spurr volcano, south central Alaska

1994 ◽  
Vol 99 (B8) ◽  
pp. 15305 ◽  
Author(s):  
Arthur D. Jolly ◽  
Robert A. Page ◽  
John A. Power
Keyword(s):  
South Central ◽  
Mount Spurr

scholarly journals Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska

2014 ◽  
Author(s):  
T. M. Herriott ◽  
C. J. Nye ◽  
R. D. Reger ◽  
M. A. Wartes ◽  
D. L. LePain ◽  
...  
Keyword(s):  
South Central ◽  
Mount Spurr ◽  
Age Constraints ◽  
Volcaniclastic Succession

Radiocarbon Age of Soil Organic Matter Fractions Buried by Tephra in Alaska

Radiocarbon ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 465-472 ◽  
Author(s):  
Alexander Cherkinsky ◽  
Kristi Wallace
Keyword(s):  
Organic Matter ◽  
Humic Acid ◽  
Bulk Soil ◽  
Radiocarbon Age ◽  
South Central ◽  
Eruption Frequency ◽  
Contamination Of Soils ◽  
The Difference ◽  
Organic Matter Fractions ◽  
Mount Spurr

AbstractRadiocarbon ages were determined on different fractions extracted from buried paleosols in south-central Alaska as an experiment to establish best practices for analysis of low-organic-matter paleosols. Seven samples were collected from directly beneath tephra deposits to determine the eruption frequency of Mount Spurr Volcano, Alaska. Soil development near the volcano is poor due to the high-latitude climate and frequent burial of soil surfaces by tephra. Contamination of soils by local wind-blown material is a concern. The humic acid 14C ages are consistently younger than both the bulk soil and residue after extraction ages. The difference in ages between the humic acid extract and bulk soil range from 60–1130 14C yr BP and 180–4110 14C yr BP, respectively, for residue. Previous observations from dating different soil fractions show that residue ages are typically younger than humic acid extracts presumably because they contain a fraction of younger plant material including roots. We attribute the older ages to contamination by old carbon from eolian charcoal particles. This study supports the use of accelerator mass spectrometry (AMS) 14C dating of the humic acid fraction in order to estimate the age of soil that presumably marks the age of burial and avoids suspected contamination by old carbon.

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