John N Aleinikoff
John Aleinikoff is a Scientist Emeritus with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 109
P-T-t paths and differential Alleghanian loading and uplift of the Bronson Hill terrane south central New England P-T-t paths and differential Alleghanian loading and uplift of the Bronson Hill terrane south central New England
Late Paleozoic U-Pb ages of sphene and 40Ar/39Ar cooling ages of amphibole and muscovite from rocks of the Bronson Hill terrane in Connecticut and central Massachusetts reflect a late Paleozoic (Alleghanian) overprint on Acadian metamorphic rocks. Prograde Alleghanian sphenes crystallized during the Late Pennsylvanian, and eliminate the possibility that amphibole ages reflect delayed...
Authors
R. P. Wintsch, Michael J. Kunk, J.L. Boyd, J. N. Aleinikoff
TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology
The role of the standard is critical to the derivation of reliable U-Pb zircon ages by micro-beam analysis. For maximum reliability, it is critically important that the utilised standard be homogeneous at all scales of analysis. It is equally important that the standard has been precisely and accurately dated by an independent technique. This study reports the emergence of a new zircon...
Authors
L.P. Black, S.L. Kamo, C. M. Allen, J. N. Aleinikoff, D.W. Davis, R.J. Korsch, C. Foudoulis
SHRIMP and Conventional UPb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events SHRIMP and Conventional UPb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events
Discordant Cambrian U-Pb ages of questionable reliability for metamor-phosed plutonic rocks in the central Appalachian Piedmont of northern Virginia, Maryland, and the District of Columbia have led to different regional geologic interpretations and controversies. In this study, we use the sensitive high resolution ion microprobe (SHRIMP) for dating 25-m diameter areas on individual...
Authors
John N. Aleinikoff, J. Wright Horton,, Avery Ala Drake
U-Pb zircon geochronology of the Paleoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco U-Pb zircon geochronology of the Paleoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco
New U-Pb zircon data obtained by sensitive high resolution ion microprobe (SHRIMP) from the Tagragra de Tata inlier in the western Anti-Atlas, Morocco establish Paleoproterozoic ages for the basement schists, granites, and metadolerites, and a Neoproterozoic age for an ignimbrite of the Ouarzazate Series in the cover sequence. The age of interbedded felsic metatuff in the metasedimentary...
Authors
G. J. Walsh, J. N. Aleinikoff, F. Benziane, A. Yazidi, T. R. Armstrong
U-Pb geochronology of zircon and polygenetic titanite from the Glastonbury Complex, Connecticut, USA: An integrated SEM, EMPA, TIMS, and SHRIMP study U-Pb geochronology of zircon and polygenetic titanite from the Glastonbury Complex, Connecticut, USA: An integrated SEM, EMPA, TIMS, and SHRIMP study
U-Pb ages for zircon and titanite from a granodioritic gneiss in the Glastonbury Complex, Connecticut, have been determined using both isotope dilution thermal ionization mass spectrometry (TIMS) and the sensitive high resolution ion microprobe (SHRIMP). Zircons occur in three morphologic populations: (1) equant to stubby, multifaceted, colorless, (2) prismatic, dark brown, with numerous...
Authors
J. N. Aleinikoff, R. P. Wintsch, C.M. Fanning, M. J. Dorais
Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England
The Ammonoosuc Volcanics, Partridge Formation, and the Oliverian and Highlandcroft Plutonic Suites of the Bronson Hill anticlinorium (BHA) in axial New England are widely accepted as a single Middle to Late Ordovician magmatic arc that was active during closure of Iapetus. Mapping and U–Pb dating indicate, however, that the BHA contains two volcano-sedimentary-intrusive sequences of...
Authors
R. H. Moench, J. N. Aleinikoff
Science and Products
Filter Total Items: 109
P-T-t paths and differential Alleghanian loading and uplift of the Bronson Hill terrane south central New England P-T-t paths and differential Alleghanian loading and uplift of the Bronson Hill terrane south central New England
Late Paleozoic U-Pb ages of sphene and 40Ar/39Ar cooling ages of amphibole and muscovite from rocks of the Bronson Hill terrane in Connecticut and central Massachusetts reflect a late Paleozoic (Alleghanian) overprint on Acadian metamorphic rocks. Prograde Alleghanian sphenes crystallized during the Late Pennsylvanian, and eliminate the possibility that amphibole ages reflect delayed...
Authors
R. P. Wintsch, Michael J. Kunk, J.L. Boyd, J. N. Aleinikoff
TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology
The role of the standard is critical to the derivation of reliable U-Pb zircon ages by micro-beam analysis. For maximum reliability, it is critically important that the utilised standard be homogeneous at all scales of analysis. It is equally important that the standard has been precisely and accurately dated by an independent technique. This study reports the emergence of a new zircon...
Authors
L.P. Black, S.L. Kamo, C. M. Allen, J. N. Aleinikoff, D.W. Davis, R.J. Korsch, C. Foudoulis
SHRIMP and Conventional UPb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events SHRIMP and Conventional UPb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events
Discordant Cambrian U-Pb ages of questionable reliability for metamor-phosed plutonic rocks in the central Appalachian Piedmont of northern Virginia, Maryland, and the District of Columbia have led to different regional geologic interpretations and controversies. In this study, we use the sensitive high resolution ion microprobe (SHRIMP) for dating 25-m diameter areas on individual...
Authors
John N. Aleinikoff, J. Wright Horton,, Avery Ala Drake
U-Pb zircon geochronology of the Paleoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco U-Pb zircon geochronology of the Paleoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco
New U-Pb zircon data obtained by sensitive high resolution ion microprobe (SHRIMP) from the Tagragra de Tata inlier in the western Anti-Atlas, Morocco establish Paleoproterozoic ages for the basement schists, granites, and metadolerites, and a Neoproterozoic age for an ignimbrite of the Ouarzazate Series in the cover sequence. The age of interbedded felsic metatuff in the metasedimentary...
Authors
G. J. Walsh, J. N. Aleinikoff, F. Benziane, A. Yazidi, T. R. Armstrong
U-Pb geochronology of zircon and polygenetic titanite from the Glastonbury Complex, Connecticut, USA: An integrated SEM, EMPA, TIMS, and SHRIMP study U-Pb geochronology of zircon and polygenetic titanite from the Glastonbury Complex, Connecticut, USA: An integrated SEM, EMPA, TIMS, and SHRIMP study
U-Pb ages for zircon and titanite from a granodioritic gneiss in the Glastonbury Complex, Connecticut, have been determined using both isotope dilution thermal ionization mass spectrometry (TIMS) and the sensitive high resolution ion microprobe (SHRIMP). Zircons occur in three morphologic populations: (1) equant to stubby, multifaceted, colorless, (2) prismatic, dark brown, with numerous...
Authors
J. N. Aleinikoff, R. P. Wintsch, C.M. Fanning, M. J. Dorais
Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England
The Ammonoosuc Volcanics, Partridge Formation, and the Oliverian and Highlandcroft Plutonic Suites of the Bronson Hill anticlinorium (BHA) in axial New England are widely accepted as a single Middle to Late Ordovician magmatic arc that was active during closure of Iapetus. Mapping and U–Pb dating indicate, however, that the BHA contains two volcano-sedimentary-intrusive sequences of...
Authors
R. H. Moench, J. N. Aleinikoff