Heather A Lowers
Heather Lowers is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 31
USGS Spectral Library Version 7 Data USGS Spectral Library Version 7 Data
This data release provides the U.S. Geological Survey (USGS) Spectral Library Version 7 and all related documents. The library contains spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns). Laboratory samples of specific minerals, plants, chemical compounds, and man-made...
Filter Total Items: 106
Petrogenesis and rare earth element mineralization of the Elk Creek carbonatite, Nebraska, USA Petrogenesis and rare earth element mineralization of the Elk Creek carbonatite, Nebraska, USA
Although carbonatites are the primary source of the world’s rare earth elements (REEs), the processes responsible for ore-grade REE enrichment in carbonatites are still poorly understood. In this study, we present a petrologic, geochemical, and isotopic evaluation of the Elk Creek carbonatite in southeast Nebraska to constrain the origin of REE mineralization. The Elk Creek carbonatite...
Authors
Philip Verplanck, G. Lang Farmer, Richard M. Kettler, Heather A. Lowers, Craig A. Johnson, Alan E. Koenig, Michael J. Blessington
Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners
Rationale: The reasons for resurgent coal workers’ pneumoconiosis and its most severe forms, rapidly progressive pneumoconiosis and progressive massive fibrosis (PMF), in the United States (US) are not yet fully understood. Objective: To compare the pathologic and mineralogic features of contemporary coal miners suffering severe pneumoconiosis to their historical counterparts. Methods...
Authors
R. A. Cohen, Cecil S. Rose, L. H. Go, Lauren M. Zell-Baran, K. S. Almberg, Emily A. Sarver, Heather A. Lowers, C. Iwaniuk, S. Clingerman, D. Richardson, J.L. Abraham, Carlyne D. Cool, A. Franko, A.F. Hubbs, J. D. Murray, M.S. Orandle, S. Sanyal, N.I. Vorajee, E.L. Petsonk, R. Zulfikar, F.H. Green
Approach for quantifying rare Earth elements at low keV Approach for quantifying rare Earth elements at low keV
The challenges of analyzing bastnaesite (REECO3F) and hydroxylbastnaesite (REECO3OH) include beam sensitivity, quantification of light elements in a heavy element matrix, the presence of elements that cannot be analyzed with EPMA (H), and the use of x-ray lines whose physical constants are not well known. To overcome some of these challenges, Ca, La, Ce, Pr, Nd, and Sm were analyzed at...
Authors
Heather A. Lowers
Pyritization history in the middle to upper Cambrian Alum Shale, Scania Sweden: Evidence for ongoing diagenetic processes Pyritization history in the middle to upper Cambrian Alum Shale, Scania Sweden: Evidence for ongoing diagenetic processes
Detailed diagenetic studies of the late Cambrian Alum Shale in southern Sweden were undertaken across an interval that includes the peak Steptoean Positive Carbon Isotope Excursion (SPICE) event to evaluate the pyrite mineralization history in the formation. Samples were collected from the Andrarum-3 core (Scania, Sweden); here the Alum was deposited in the distal, siliciclastic mudstone...
Authors
Neil S. Fishman, Sven O. Egenhoff, Heather A. Lowers, Adam Boehlke, Per Ahlberg
The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden
The Lower to Middle Ordovician Tøyen Shale in southern Sweden, a biostratigraphically well-dated siliciclastic mudstone unit, shows 18 distinct authigenic cements that include sulfides, carbonates, silicates, clays, and phosphates. Marcasite, sphalerite, galena, and six texturally distinct types of pyrite characterize the sulfides whereas only one type of dolomite and three different...
Authors
Sven Egenhoff, Neil Fishman, Heather A. Lowers, Per Ahlberg
Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS...
Authors
Corey J. Meighan, Albert H. Hofstra, David Adams, Erin E. Marsh, Heather A. Lowers, Alan Koenig
Science and Products
Filter Total Items: 31
USGS Spectral Library Version 7 Data USGS Spectral Library Version 7 Data
This data release provides the U.S. Geological Survey (USGS) Spectral Library Version 7 and all related documents. The library contains spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns). Laboratory samples of specific minerals, plants, chemical compounds, and man-made...
Filter Total Items: 106
Petrogenesis and rare earth element mineralization of the Elk Creek carbonatite, Nebraska, USA Petrogenesis and rare earth element mineralization of the Elk Creek carbonatite, Nebraska, USA
Although carbonatites are the primary source of the world’s rare earth elements (REEs), the processes responsible for ore-grade REE enrichment in carbonatites are still poorly understood. In this study, we present a petrologic, geochemical, and isotopic evaluation of the Elk Creek carbonatite in southeast Nebraska to constrain the origin of REE mineralization. The Elk Creek carbonatite...
Authors
Philip Verplanck, G. Lang Farmer, Richard M. Kettler, Heather A. Lowers, Craig A. Johnson, Alan E. Koenig, Michael J. Blessington
Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners
Rationale: The reasons for resurgent coal workers’ pneumoconiosis and its most severe forms, rapidly progressive pneumoconiosis and progressive massive fibrosis (PMF), in the United States (US) are not yet fully understood. Objective: To compare the pathologic and mineralogic features of contemporary coal miners suffering severe pneumoconiosis to their historical counterparts. Methods...
Authors
R. A. Cohen, Cecil S. Rose, L. H. Go, Lauren M. Zell-Baran, K. S. Almberg, Emily A. Sarver, Heather A. Lowers, C. Iwaniuk, S. Clingerman, D. Richardson, J.L. Abraham, Carlyne D. Cool, A. Franko, A.F. Hubbs, J. D. Murray, M.S. Orandle, S. Sanyal, N.I. Vorajee, E.L. Petsonk, R. Zulfikar, F.H. Green
Approach for quantifying rare Earth elements at low keV Approach for quantifying rare Earth elements at low keV
The challenges of analyzing bastnaesite (REECO3F) and hydroxylbastnaesite (REECO3OH) include beam sensitivity, quantification of light elements in a heavy element matrix, the presence of elements that cannot be analyzed with EPMA (H), and the use of x-ray lines whose physical constants are not well known. To overcome some of these challenges, Ca, La, Ce, Pr, Nd, and Sm were analyzed at...
Authors
Heather A. Lowers
Pyritization history in the middle to upper Cambrian Alum Shale, Scania Sweden: Evidence for ongoing diagenetic processes Pyritization history in the middle to upper Cambrian Alum Shale, Scania Sweden: Evidence for ongoing diagenetic processes
Detailed diagenetic studies of the late Cambrian Alum Shale in southern Sweden were undertaken across an interval that includes the peak Steptoean Positive Carbon Isotope Excursion (SPICE) event to evaluate the pyrite mineralization history in the formation. Samples were collected from the Andrarum-3 core (Scania, Sweden); here the Alum was deposited in the distal, siliciclastic mudstone...
Authors
Neil S. Fishman, Sven O. Egenhoff, Heather A. Lowers, Adam Boehlke, Per Ahlberg
The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden
The Lower to Middle Ordovician Tøyen Shale in southern Sweden, a biostratigraphically well-dated siliciclastic mudstone unit, shows 18 distinct authigenic cements that include sulfides, carbonates, silicates, clays, and phosphates. Marcasite, sphalerite, galena, and six texturally distinct types of pyrite characterize the sulfides whereas only one type of dolomite and three different...
Authors
Sven Egenhoff, Neil Fishman, Heather A. Lowers, Per Ahlberg
Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS...
Authors
Corey J. Meighan, Albert H. Hofstra, David Adams, Erin E. Marsh, Heather A. Lowers, Alan Koenig