Dawnika is a Research Geologist with the California Volcano Observatory (CalVO). She conducts high-pressure, high-temperature experimental studies in the Magma Dynamics laboratory to complement field and petrologic studies of volcanic systems.
Dawnika works on understanding magmas, including their melt, crystal, and volatile components as they form, undergo evolution, and ultimately erupt (or not). She uses experimental petrology, coupled with microbeam analyses, FTIR, and petrographic data, to determine magmatic conditions including: temperature, pressure, oxygen fugacity, and compositions and proportions of all phases (including volatiles). She combines this information with field observations on distribution, timing, and volumes of eruptive products to connect eruptive processes to fundamental source conditions. Field-based projects include extensive mapping and sampling across the Mexican Volcanic Belt, work on Cascade arc volcanoes, Aleutian arc volcanoes, and most recently in the Clear Lake Volcanic Field and Mount Shasta region of northern California.
Education and Certifications
Ph.D. in Geology and Geophysics, 1998, University of California, Berkeley
Dissertation Title: Subduction-related volcanism: Field and experimental studies of hydrous lavas in central Mexico
B.S. with Honors in Geology, 1991, University of California, Davis.
Science and Products
Dataset establishing garnet stability in arc basalt, andesite, and dacite – an experimental study
These data are geochemical analyses of phase equilibria experiments.
Dataset Establishing Temporal Duration of Two Shield Volcanoes in Northern California
This dataset contains paleomagnetic data from 30 sites at two locations in northern California (16 sites at Ash Creek Butte and 14 sites at Crater Mountain), magnetic susceptibility-temperature curves for selected samples at Ash Creek Butte, and geochemical data for map units at Crater Mountain.
Garnet stability in arc basalt, andesite, and dacite—An experimental study
Garnet’s stability in arc magmas and its influences on their differentiation were explored experimentally in a typical basalt, andesite, and dacite at conditions of 0.9–1.67 GPa, 800–1300 °C, with 2–9 wt.% added H2O, and with oxygen fugacity buffered near Re + O2 = ReO2 (~ Ni-NiO + 1.7 log10 bars). Garnet did not grow at 0.9 GPa in any of the compositions, even with garnet seeds added to facilitat
Authors
Dawnika Blatter, Thomas W. Sisson, W. Ben Hankins
Paleomagnetically defined brief lifespans for two large shield volcanoes in the Cascades Arc
Mafic to intermediate shield volcanoes with multi-cubic-kilometer eruptive volumes are common in the Cascades Volcanic Arc, but little is known about their eruptive histories as either singular or sustained episodes, or the total time required for their construction. Paleomagnetic data were collected from the lava flows of Ash Creek Butte (17 sites) and Crater Mountain (14 sites) in northern Calif
Authors
Anthony Francis Pivarunas, Dawnika Blatter, L. J. Patrick Muffler, Michael A. Clynne, Andrew T. Calvert, Lauren N Harrison, R.L. Christiansen
Barometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions
The composition of clinopyroxene and clinopyroxene-liquid (Cpx-Liq) pairs are frequently used to calculate crystallization/equilibration pressures in igneous systems. While canonical uncertainties are often assigned to calculated pressures based on fits to calibration or test datasets, the sources of these uncertainties (and thus ways to reduce them) have not been rigorously assessed. We show that
Authors
Penny E. Wieser, Adam J.R. Kent, Christy B. Till, J. Donovan, David A. Neave, Dawnika Blatter, Michael J. Krawczynski
Water contents of clinopyroxenes from sub-arc mantle peridotites
One poorly constrained reservoir of the Earth's water budget is that of clinopyroxene in metasomatised, mantle peridotites. This study presents reconnaissance Sensitive High-Resolution, Ion Microprobe–Stable Isotope (SHRIMP–SI) determinations of the H2O contents of (dominantly) clinopyroxenes in rare mantle xenoliths from four different subduction zones, i.e. Mexico, Kamchatka, Philippines, and Ne
Authors
Michael Turner, Simon Turner, Dawnika Blatter, Rene Maury, Michael Perfit, Gene Yogodzinski
Voluminous arc dacites as amphibole reaction-boundary liquids
Dacites dominate the large-volume, explosive eruptions in magmatic arcs, and compositionally similar granodiorites and tonalites constitute the bulk of convergent margin batholiths. Shallow, pre-eruptive storage conditions are well known for many dacitic arc magmas through melt inclusions, Fe–Ti oxides, and experiments, but their potential origins deeper in the crust are not well determined. Accor
Authors
Dawnika Blatter, Thomas W. Sisson, William B. Hankins
Crystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis
This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H2O and oxidation on differentiation are less well established. Accordingly, we
Authors
Dawnika L. Blatter, Thomas W. Sisson, W. Ben Hankins
Non-USGS Publications**
Blatter, D.L. and Carmichael, I.S.E. (1998) Hornblende peridotite xenoliths from central Mexico reveal the highly-oxidized nature of subarc upper mantle. Geology, v. 26, pp. 1035-1038.
Blatter, D.L. and Carmichael, I.S.E. (1998) Plagioclase-free andesites from Zitácuaro (Michoacán), Mexico: petrology and experimental constraints. Contributions to Mineralogy and Petrology, v. 132, pp. 121-138.
Blatter, D.L, and Carmichael, I.S.E. (2001) Hydrous phase equilibria of a Mexican high-silica andesite: A candidate for a direct mantle origin? Geochimica et Cosmochimica Acta, v. 65, pp. 4041-4063.
Blatter, D.L, Carmichael, I.S.E, Deino, A, and Renne, P. (2001) Neogene volcanism at the front of the central Mexican Volcanic Belt: basaltic andesites to dacites with contemporaneous shoshonites and high-TiO2 lavas. GSA Bulletin, v. 113, pp. 1324-1342.
Blatter, D.L, Carmichael, I.S.E, Deino, A, and Renne, P. (2003) Reply to comment by Torres-Alvarado, I. S. and Verma, S. P. on Neogene volcanism at the front of the central Mexican Volcanic Belt: basaltic andesites to dacites with contemporaneous shoshonites and high-TiO2 lavas. GSA Bulletin, v. 115, pp. 1021-1024.
Blatter, D.L, Farmer, G. L, and Carmichael, I.S.E. (2007) A N-S transect across the central Mexican Volcanic Belt at ~100°W: spatial distribution, petrologic, geochemical, and isotopic characteristics of Quaternary volcanism. Journal of Petrology, v. 48, pp. 901-950.
Mukasa, S.B, Blatter, D.L, and Andronikov, A. (2007) Mantle peridotite xenoliths in andesite lava at El Peñon, central Mexican Volcanic Belt: Isotopic and trace element evidence for melting and metasomatism in the mantle wedge beneath an active arc. Earth and Planetary Science Letters, v. 260, pp. 37-55.
Blatter, D.L, and Hammersley, L. (2010) Impact of the Orozco Fracture Zone on the central Mexican Volcanic Belt. Journal of Volcanology and Geothermal Research, v.197, pp. 67-84. DOI 10.1016/j.jvolgeores.2009.08.002.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Data
Dataset establishing garnet stability in arc basalt, andesite, and dacite – an experimental study
These data are geochemical analyses of phase equilibria experiments.Dataset Establishing Temporal Duration of Two Shield Volcanoes in Northern California
This dataset contains paleomagnetic data from 30 sites at two locations in northern California (16 sites at Ash Creek Butte and 14 sites at Crater Mountain), magnetic susceptibility-temperature curves for selected samples at Ash Creek Butte, and geochemical data for map units at Crater Mountain. - Publications
Garnet stability in arc basalt, andesite, and dacite—An experimental study
Garnet’s stability in arc magmas and its influences on their differentiation were explored experimentally in a typical basalt, andesite, and dacite at conditions of 0.9–1.67 GPa, 800–1300 °C, with 2–9 wt.% added H2O, and with oxygen fugacity buffered near Re + O2 = ReO2 (~ Ni-NiO + 1.7 log10 bars). Garnet did not grow at 0.9 GPa in any of the compositions, even with garnet seeds added to facilitatAuthorsDawnika Blatter, Thomas W. Sisson, W. Ben HankinsPaleomagnetically defined brief lifespans for two large shield volcanoes in the Cascades Arc
Mafic to intermediate shield volcanoes with multi-cubic-kilometer eruptive volumes are common in the Cascades Volcanic Arc, but little is known about their eruptive histories as either singular or sustained episodes, or the total time required for their construction. Paleomagnetic data were collected from the lava flows of Ash Creek Butte (17 sites) and Crater Mountain (14 sites) in northern CalifAuthorsAnthony Francis Pivarunas, Dawnika Blatter, L. J. Patrick Muffler, Michael A. Clynne, Andrew T. Calvert, Lauren N Harrison, R.L. ChristiansenBarometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions
The composition of clinopyroxene and clinopyroxene-liquid (Cpx-Liq) pairs are frequently used to calculate crystallization/equilibration pressures in igneous systems. While canonical uncertainties are often assigned to calculated pressures based on fits to calibration or test datasets, the sources of these uncertainties (and thus ways to reduce them) have not been rigorously assessed. We show thatAuthorsPenny E. Wieser, Adam J.R. Kent, Christy B. Till, J. Donovan, David A. Neave, Dawnika Blatter, Michael J. KrawczynskiWater contents of clinopyroxenes from sub-arc mantle peridotites
One poorly constrained reservoir of the Earth's water budget is that of clinopyroxene in metasomatised, mantle peridotites. This study presents reconnaissance Sensitive High-Resolution, Ion Microprobe–Stable Isotope (SHRIMP–SI) determinations of the H2O contents of (dominantly) clinopyroxenes in rare mantle xenoliths from four different subduction zones, i.e. Mexico, Kamchatka, Philippines, and NeAuthorsMichael Turner, Simon Turner, Dawnika Blatter, Rene Maury, Michael Perfit, Gene YogodzinskiVoluminous arc dacites as amphibole reaction-boundary liquids
Dacites dominate the large-volume, explosive eruptions in magmatic arcs, and compositionally similar granodiorites and tonalites constitute the bulk of convergent margin batholiths. Shallow, pre-eruptive storage conditions are well known for many dacitic arc magmas through melt inclusions, Fe–Ti oxides, and experiments, but their potential origins deeper in the crust are not well determined. AccorAuthorsDawnika Blatter, Thomas W. Sisson, William B. HankinsCrystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis
This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H2O and oxidation on differentiation are less well established. Accordingly, weAuthorsDawnika L. Blatter, Thomas W. Sisson, W. Ben HankinsNon-USGS Publications**
Blatter, D.L. and Carmichael, I.S.E. (1998) Hornblende peridotite xenoliths from central Mexico reveal the highly-oxidized nature of subarc upper mantle. Geology, v. 26, pp. 1035-1038.Blatter, D.L. and Carmichael, I.S.E. (1998) Plagioclase-free andesites from Zitácuaro (Michoacán), Mexico: petrology and experimental constraints. Contributions to Mineralogy and Petrology, v. 132, pp. 121-138.Blatter, D.L, and Carmichael, I.S.E. (2001) Hydrous phase equilibria of a Mexican high-silica andesite: A candidate for a direct mantle origin? Geochimica et Cosmochimica Acta, v. 65, pp. 4041-4063.Blatter, D.L, Carmichael, I.S.E, Deino, A, and Renne, P. (2001) Neogene volcanism at the front of the central Mexican Volcanic Belt: basaltic andesites to dacites with contemporaneous shoshonites and high-TiO2 lavas. GSA Bulletin, v. 113, pp. 1324-1342.Blatter, D.L, Carmichael, I.S.E, Deino, A, and Renne, P. (2003) Reply to comment by Torres-Alvarado, I. S. and Verma, S. P. on Neogene volcanism at the front of the central Mexican Volcanic Belt: basaltic andesites to dacites with contemporaneous shoshonites and high-TiO2 lavas. GSA Bulletin, v. 115, pp. 1021-1024.Blatter, D.L, Farmer, G. L, and Carmichael, I.S.E. (2007) A N-S transect across the central Mexican Volcanic Belt at ~100°W: spatial distribution, petrologic, geochemical, and isotopic characteristics of Quaternary volcanism. Journal of Petrology, v. 48, pp. 901-950.Mukasa, S.B, Blatter, D.L, and Andronikov, A. (2007) Mantle peridotite xenoliths in andesite lava at El Peñon, central Mexican Volcanic Belt: Isotopic and trace element evidence for melting and metasomatism in the mantle wedge beneath an active arc. Earth and Planetary Science Letters, v. 260, pp. 37-55.Blatter, D.L, and Hammersley, L. (2010) Impact of the Orozco Fracture Zone on the central Mexican Volcanic Belt. Journal of Volcanology and Geothermal Research, v.197, pp. 67-84. DOI 10.1016/j.jvolgeores.2009.08.002.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.