Julie Donnelly-nolan - Academia.edu (original) (raw)

Uploads

Papers by Julie Donnelly-nolan

Open-file report /, 1996

This report lists oxygen isotope data for 166 rock samples from at least 45 eruptive units on and... more This report lists oxygen isotope data for 166 rock samples from at least 45 eruptive units on and adjacent to Medicine Lake volcano, northern California (table 1). Locations of the samples are indicated by latitude and longitude in table 1 and shown on figures 1 and 2. Sixty-three of the samples are inclusions collected from lava flows. Most of these (54) are from late Holocene flows, including 7 from mafic flows and 47 from silicic flows (see fig. 2). Inclusion type is indicated in table 1, based on petrographic criteria. Of the 102 samples that are not inclusions, 24 are from late Holocene flows and 17 others are from post-glacial lava flows erupted about 10,600 years B.P. (Donnelly-Nolan and others, 1990). All late Holocene eruptions are represented in the data set, and all but two of 17 known post-glacial eruptions are included. Four samples are thought to be of Pleistocene age but erupted prior to initiation of Medicine Lake volcano; these are identified in table 1. The remaining 57 samples were collected from Pleistocene lavas in all sectors of the volcano. Previous oxygen isotope data for lavas from Medicine Lake volcano were published by Taylor (1968). Taylor's data are in generally good agreement with the data presented here in table 1, where it is possible to correlate units.

AGU Fall Meeting Abstracts, Dec 1, 2005

525 volcanic vents 0-2 Ma were identified during geologic mapping of approx. 2500 sq km centered ... more 525 volcanic vents 0-2 Ma were identified during geologic mapping of approx. 2500 sq km centered on Medicine Lake volcano (MLv), northern Calif. More than 95% of the mapped area consists of volcanic rocks 0-2 Ma. Vent locations were digitized, and each vent assigned to 1 of 5 time slices (0-12 ka, 12-25 ka, 25-120 ka, 120-780 ka, and 0.780-2

Scientific Investigations Map, 2015

D. Map showing Newberry Volcano's youngest lava flow, the 1,300-yr-old Big Obsidian Flow (orange)... more D. Map showing Newberry Volcano's youngest lava flow, the 1,300-yr-old Big Obsidian Flow (orange). This eruption began with explosions that sent volcanic ash east as far as Idaho. The lava dome (D1) above the main vent stands above the craggy surface of the obsidian flow. The lava flow's inhospitable surface is pockmarked by round gas-related cavities (D2), and wrinkled by lava flow pressure ridges (D3) showing flow direction to the north. A popular unpaved hiking trail (black dash-dot line) ascends by stairs to the upper surface of this spectacular rhyolite flow. Overlooking the Big Obsidian Flow is the nearly 8,000-ft-high Paulina Peak (D4), the highest point on the caldera rim. The peak is made of rhyolite that erupted about 80,000 years ago. The caldera collapse and subsequent glaciation beheaded the lava flow, and sections of these oversteepened cliffs collapsed to form the landslide (D5) that appears as the rumpled surface below the peak. An unpaved seasonal road ascends to the top of the peak that, on a clear day, offers one of the premier views in all of Oregon-the crest of the Cascade Range from Mount Shasta, CA to Mount Adams, WA. C. Map showing the central rhyolite fissure (red) that erupted across the caldera about 7,500 years ago and includes craggy-surfaced lava flows and the nearly 700-ft-high Central Pumice Cone (C1). This prominent feature was built by the explosive interaction of rhyolitic magma and water. As the cone grew, water was forced away from the vent, allowing lava to ooze into the central crater. North of the cone, the Inter Lake Flow (C2) flowed south and then descended both sides of the central ridge into the basins occupied by the caldera lakes. The East Lake Fissure (C3), shown in purple, marks the extension of the northwest rift zone eruption into the caldera.

AGU Fall Meeting Abstracts, Dec 1, 2012

Scientific Investigations Map, 2011

Geological Society of America eBooks, Nov 20, 2007

Open-file report /, 2008

Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene... more Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene rocks collected at and near Medicine Lake Volcano, northern California. The data include major-element X-ray fluorescence (XRF) analyses for all of the rocks plus XRF trace element data for most samples, and instrumental neutron activation analysis (INAA) trace element data for many samples. In addition, a limited number of analyses of Na 2 O and K 2 O by flame photometry (FP) are included as well as some wet chemical analyses of FeO, H 2 O+/-, and CO 2. Latitude and longitude location information is provided for all samples. This data set is intended to accompany the geologic map of Medicine Lake Volcano (Donnelly-Nolan, in press); map unit designations are given for each sample collected from the map area.

Collected reprint series, Mar 3, 2014

South Cascades Arc Volcanism, California and Southern Oregon: Red Bluff to Redding, California, July 20–26, 1989, 1989

Journal of Geophysical Research: Solid Earth, 1988

Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range.... more Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range. It is located behind the main Cascade arc in an extensional tectonic setting where high‐alumina basalt is the most commonly erupted lava. This basalt is parental to the higher‐silica calc‐alkaline and tholeiitic lavas that make up the bulk of the shield. The presence of late Holocene, chemically identical rhyolites on opposite sides of the volcano led to hypotheses of a large shallow silicic magma chamber and of a small, deep chamber that fed rhyolites to the surface via cone sheets. Subsequent geophysical work has been unable to identify a large silicic magma body, and instead a small one has apparently been recognized. Some geologic data support the geophysical results. Tectonic control of vent alignments and the dominance of mafic eruptions both in number of events and volume throughout the history of the volcano indicate that no large silicic magma reservoir exists. Instead, a model...

Bulletin of Volcanology, 2001

Open-file report /, 1996

This report lists oxygen isotope data for 166 rock samples from at least 45 eruptive units on and... more This report lists oxygen isotope data for 166 rock samples from at least 45 eruptive units on and adjacent to Medicine Lake volcano, northern California (table 1). Locations of the samples are indicated by latitude and longitude in table 1 and shown on figures 1 and 2. Sixty-three of the samples are inclusions collected from lava flows. Most of these (54) are from late Holocene flows, including 7 from mafic flows and 47 from silicic flows (see fig. 2). Inclusion type is indicated in table 1, based on petrographic criteria. Of the 102 samples that are not inclusions, 24 are from late Holocene flows and 17 others are from post-glacial lava flows erupted about 10,600 years B.P. (Donnelly-Nolan and others, 1990). All late Holocene eruptions are represented in the data set, and all but two of 17 known post-glacial eruptions are included. Four samples are thought to be of Pleistocene age but erupted prior to initiation of Medicine Lake volcano; these are identified in table 1. The remaining 57 samples were collected from Pleistocene lavas in all sectors of the volcano. Previous oxygen isotope data for lavas from Medicine Lake volcano were published by Taylor (1968). Taylor's data are in generally good agreement with the data presented here in table 1, where it is possible to correlate units.

AGU Fall Meeting Abstracts, Dec 1, 2005

525 volcanic vents 0-2 Ma were identified during geologic mapping of approx. 2500 sq km centered ... more 525 volcanic vents 0-2 Ma were identified during geologic mapping of approx. 2500 sq km centered on Medicine Lake volcano (MLv), northern Calif. More than 95% of the mapped area consists of volcanic rocks 0-2 Ma. Vent locations were digitized, and each vent assigned to 1 of 5 time slices (0-12 ka, 12-25 ka, 25-120 ka, 120-780 ka, and 0.780-2

Scientific Investigations Map, 2015

D. Map showing Newberry Volcano's youngest lava flow, the 1,300-yr-old Big Obsidian Flow (orange)... more D. Map showing Newberry Volcano's youngest lava flow, the 1,300-yr-old Big Obsidian Flow (orange). This eruption began with explosions that sent volcanic ash east as far as Idaho. The lava dome (D1) above the main vent stands above the craggy surface of the obsidian flow. The lava flow's inhospitable surface is pockmarked by round gas-related cavities (D2), and wrinkled by lava flow pressure ridges (D3) showing flow direction to the north. A popular unpaved hiking trail (black dash-dot line) ascends by stairs to the upper surface of this spectacular rhyolite flow. Overlooking the Big Obsidian Flow is the nearly 8,000-ft-high Paulina Peak (D4), the highest point on the caldera rim. The peak is made of rhyolite that erupted about 80,000 years ago. The caldera collapse and subsequent glaciation beheaded the lava flow, and sections of these oversteepened cliffs collapsed to form the landslide (D5) that appears as the rumpled surface below the peak. An unpaved seasonal road ascends to the top of the peak that, on a clear day, offers one of the premier views in all of Oregon-the crest of the Cascade Range from Mount Shasta, CA to Mount Adams, WA. C. Map showing the central rhyolite fissure (red) that erupted across the caldera about 7,500 years ago and includes craggy-surfaced lava flows and the nearly 700-ft-high Central Pumice Cone (C1). This prominent feature was built by the explosive interaction of rhyolitic magma and water. As the cone grew, water was forced away from the vent, allowing lava to ooze into the central crater. North of the cone, the Inter Lake Flow (C2) flowed south and then descended both sides of the central ridge into the basins occupied by the caldera lakes. The East Lake Fissure (C3), shown in purple, marks the extension of the northwest rift zone eruption into the caldera.

AGU Fall Meeting Abstracts, Dec 1, 2012

Scientific Investigations Map, 2011

Geological Society of America eBooks, Nov 20, 2007

Open-file report /, 2008

Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene... more Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene rocks collected at and near Medicine Lake Volcano, northern California. The data include major-element X-ray fluorescence (XRF) analyses for all of the rocks plus XRF trace element data for most samples, and instrumental neutron activation analysis (INAA) trace element data for many samples. In addition, a limited number of analyses of Na 2 O and K 2 O by flame photometry (FP) are included as well as some wet chemical analyses of FeO, H 2 O+/-, and CO 2. Latitude and longitude location information is provided for all samples. This data set is intended to accompany the geologic map of Medicine Lake Volcano (Donnelly-Nolan, in press); map unit designations are given for each sample collected from the map area.

Collected reprint series, Mar 3, 2014

South Cascades Arc Volcanism, California and Southern Oregon: Red Bluff to Redding, California, July 20–26, 1989, 1989

Journal of Geophysical Research: Solid Earth, 1988

Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range.... more Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range. It is located behind the main Cascade arc in an extensional tectonic setting where high‐alumina basalt is the most commonly erupted lava. This basalt is parental to the higher‐silica calc‐alkaline and tholeiitic lavas that make up the bulk of the shield. The presence of late Holocene, chemically identical rhyolites on opposite sides of the volcano led to hypotheses of a large shallow silicic magma chamber and of a small, deep chamber that fed rhyolites to the surface via cone sheets. Subsequent geophysical work has been unable to identify a large silicic magma body, and instead a small one has apparently been recognized. Some geologic data support the geophysical results. Tectonic control of vent alignments and the dominance of mafic eruptions both in number of events and volume throughout the history of the volcano indicate that no large silicic magma reservoir exists. Instead, a model...

Bulletin of Volcanology, 2001