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Papers by R. Damian Nance

Geological Society, London, Special Publications, Sep 8, 2020

2012 GSA Annual Meeting in Charlotte, Nov 5, 2012

Over the past two decades, data from a wide variety of sources have led to the realization that P... more Over the past two decades, data from a wide variety of sources have led to the realization that Pangea was just the most recent in a series of supercontinents that have punctuated Earth history for billions of years. This record of episodic supercontinent assembly and breakup is now recognized to have profoundly influenced Earth's geologic, climatic and biological evolution. The supercontinent cycle documents a fundamental aspect of Earth dynamics and its recognition is arguably the most important development in Earth Science ...

Joint 52nd Northeastern Annual Section and 51st North-Central Annual GSA Section Meeting - 2017, 2017

GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016

Geological Society of America eBooks, 1996

Along the southeastern margin of the Appalachian-Caledonide orogen from the Florida subsurface to... more Along the southeastern margin of the Appalachian-Caledonide orogen from the Florida subsurface to the Cadomian massifs of Armorica and Bohemia (Fig. 1) lies a collection of suspect terranes that have been traditionally associated with the eastern (Gondwanan) margin of the early Paleozoic Iapetus ocean (eg, Williams, 1978b; Anderton et al., 1979; Cocks and Fortey, 1982), but which record histories of Neoproterozoic subduction that predate the inception of the Iapetus cycle (eg, O'Brien et al., 1983; Rast and Skehan, 1983 ...

Annals of the New York Academy of Sciences, Jun 28, 2022

Earth's long‐term climate has been profoundly influenced by the episodic assembly and breakup... more Earth's long‐term climate has been profoundly influenced by the episodic assembly and breakup of supercontinents at intervals of ca. 500 m.y. This reflects the cycle's impact on global sea level and atmospheric CO2 (and other greenhouse gases), the levels of which have fluctuated in response to variations in input from volcanism and removal (as carbonate) by the chemical weathering of silicate minerals. Supercontinent amalgamation tends to coincide with climatic cooling due to drawdown of atmospheric CO2 through enhanced weathering of the orogens of supercontinent assembly and a thermally uplifted supercontinent. Conversely, breakup tends to coincide with increased atmospheric CO2 and global warming as the dispersing continental fragments cool and subside, and weathering decreases as sea level rises. Supercontinents may also influence global climate through their causal connection to mantle plumes and large igneous provinces (LIPs) linked to their breakup. LIPs may amplify the warming trend of breakup by releasing greenhouse gases or may cause cooling and glaciation through sulfate aerosol release and drawdown of CO2 through the chemical weathering of LIP basalts. Hence, Earth's long‐term climatic trends likely reflect the cycle's influence on sea level, as evidenced by Pangea, whereas its influence on LIP volcanism may have orchestrated between Earth's various climatic states.

Canadian Journal of Earth Sciences, Sep 1, 1990

Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost C... more Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost Cambrian) display internally discordant 40Ar/39Ar age spectra. Gas fractions evolved at intermediate and high experimental temperatures record apparent ages of ca. 610–620 Ma. These are interpreted as dating initial cooling through temperatures appropriate for intracrystalline retention of 40Ar and may indicate derivation from mylonite zones developed within proximal late Precambrian granitic rocks. Gas fractions evolved at lower experimental temperatures record patterns of spectra discordance that suggest the constituent grains experienced partial, intracrystalline diffusive loss of 40Ar during a late Paleozoic, low-grade thermal overprint. A muscovite concentrate from pelitic schist beneath the allochthonous, latest Precambrian Cranberry Head granite records a 40Ar/39Ar plateau age of 318 ± 1 Ma. This is interpreted as closely dating Late Carboniferous thrust emplacement of the allochthon.

International Geology Review, Jan 12, 2023

Geoscience frontiers, May 1, 2019

Precambrian Research, Aug 1, 2022

International Geology Review, Feb 8, 2023

Global and Planetary Change, Aug 1, 2022

Journal of Asian Earth Sciences, Jul 1, 2022

Precambrian Research, Sep 1, 2021

Abstract The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the P... more Abstract The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the Proto-Tethys Ocean. To constrain this history, we present geochemical and zircon U-Pb geochronological data from a suite of metasedimentary rocks within this orogenic belt. Detrital zircons ages are clustered between 1000 and 400 Ma, with major peaks at ca. 510 Ma and 460 Ma, and minor peaks at ca. 840 Ma and 650 Ma. The age groups younger than 1000 Ma broadly overlap magmatic activity at ca. 540–420 Ma and minor magmatism at 920–540 Ma in the WKOB. The age data also reveal Early Paleozoic metamorphic basement rocks in the WKOB that were probably sourced from Kunlun terranes and blocks of Gondwanan affinity rather than the Tarim Craton. Compiled geochemical data suggest a protracted subduction setting in the WKOB in the Early Paleozoic. eHf(t) values show increasing trends at 900–740 Ma and 740–600 Ma and a distinct decreasing trend at 540–420 Ma, consistent with retreating subduction during the Neoproterozoic and advancing subduction in the Early Paleozoic. The retreating-advancing subduction cycle in the WKOB was possibly related to the opening and closure of the Proto-Tethys Ocean along the margin of Gondwana.

Geoscience frontiers, 2021

Trabajos de Geologia, Dec 31, 1988

A valonia, the largest suspect terrane in the Canadian Appalachians, originated along the Neoprot... more A valonia, the largest suspect terrane in the Canadian Appalachians, originated along the Neoproterozoic margin of Gondwana and was accreted to Laurentia by the late Ordovician. The age and character of A valonian basement is key to identifying the portion of the Gondwanan margin from which the terrane was derived and provides important constraints for Neoproterozoic paleocontinental reconstructions. Since this basement is not exposed, it must be characterized indirectly by isotopic analyses. Nd-Sm data from ca. crustally derived, 630-430 Ma felsic rocks typically record initial ~d values between 0 and +5.0 and model ages {TOM ) between 0.8 to I. I Ga, but the origin of this isotopic signature is unclear. Two early A valonian igneous complexes that were emplaced prior to the main (630•570 Ma) cycle of Neoproterozoic magmatism; the ca. 734 Ma Economy River Gneiss of mainland Nova Scotia and the ca. 675 Ma Malvems Plutonic Complex of the British Isles show non-overlapping eNd' values of + 1.29 to +4.09, and -0.11 to -2.03, respectively. Yet their TOM (998 -1194 Ma and 10431147 Ma) are almost identical and are similar to those of the main 630-570 Ma arc phase and subsequent Paleozoic tectonothennal events. This indicates that the isotopic signature is a characteristic feature of Avalonian basement and that felsic magmatism produced by peak arc activity was predominantly generated by recycling pre-existing crust. The T DM ages are interpreted to record a ca. 1.0 to 1.2 Ga tectonothennal event that fonned much of the basement upon which subsequent Neoproterozoic and Paleozoic tectonothennal activity developed. This interpretation is supported by U-Pb detrital zircon ages of 977-1223 Ma obtained from A valonian sedimentary rocks in Nova Scotia that are coeval with the main arc phase. This tectonothennal event is interpreted to reflect western-Pacific-type arc-back arc complexes fonned coevally with the Tocantins province of central Brazil. The transition to eastern Pacific-type arc activity may be related to the ca. 760 breakup of Rodinia in a manner analogous to effect of the breakup of Pangea on the tectonothennal evolution of western North America.

Geological Society, London, Special Publications, Sep 8, 2020

2012 GSA Annual Meeting in Charlotte, Nov 5, 2012

Over the past two decades, data from a wide variety of sources have led to the realization that P... more Over the past two decades, data from a wide variety of sources have led to the realization that Pangea was just the most recent in a series of supercontinents that have punctuated Earth history for billions of years. This record of episodic supercontinent assembly and breakup is now recognized to have profoundly influenced Earth's geologic, climatic and biological evolution. The supercontinent cycle documents a fundamental aspect of Earth dynamics and its recognition is arguably the most important development in Earth Science ...

Joint 52nd Northeastern Annual Section and 51st North-Central Annual GSA Section Meeting - 2017, 2017

GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016

Geological Society of America eBooks, 1996

Along the southeastern margin of the Appalachian-Caledonide orogen from the Florida subsurface to... more Along the southeastern margin of the Appalachian-Caledonide orogen from the Florida subsurface to the Cadomian massifs of Armorica and Bohemia (Fig. 1) lies a collection of suspect terranes that have been traditionally associated with the eastern (Gondwanan) margin of the early Paleozoic Iapetus ocean (eg, Williams, 1978b; Anderton et al., 1979; Cocks and Fortey, 1982), but which record histories of Neoproterozoic subduction that predate the inception of the Iapetus cycle (eg, O'Brien et al., 1983; Rast and Skehan, 1983 ...

Annals of the New York Academy of Sciences, Jun 28, 2022

Earth's long‐term climate has been profoundly influenced by the episodic assembly and breakup... more Earth's long‐term climate has been profoundly influenced by the episodic assembly and breakup of supercontinents at intervals of ca. 500 m.y. This reflects the cycle's impact on global sea level and atmospheric CO2 (and other greenhouse gases), the levels of which have fluctuated in response to variations in input from volcanism and removal (as carbonate) by the chemical weathering of silicate minerals. Supercontinent amalgamation tends to coincide with climatic cooling due to drawdown of atmospheric CO2 through enhanced weathering of the orogens of supercontinent assembly and a thermally uplifted supercontinent. Conversely, breakup tends to coincide with increased atmospheric CO2 and global warming as the dispersing continental fragments cool and subside, and weathering decreases as sea level rises. Supercontinents may also influence global climate through their causal connection to mantle plumes and large igneous provinces (LIPs) linked to their breakup. LIPs may amplify the warming trend of breakup by releasing greenhouse gases or may cause cooling and glaciation through sulfate aerosol release and drawdown of CO2 through the chemical weathering of LIP basalts. Hence, Earth's long‐term climatic trends likely reflect the cycle's influence on sea level, as evidenced by Pangea, whereas its influence on LIP volcanism may have orchestrated between Earth's various climatic states.

Canadian Journal of Earth Sciences, Sep 1, 1990

Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost C... more Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost Cambrian) display internally discordant 40Ar/39Ar age spectra. Gas fractions evolved at intermediate and high experimental temperatures record apparent ages of ca. 610–620 Ma. These are interpreted as dating initial cooling through temperatures appropriate for intracrystalline retention of 40Ar and may indicate derivation from mylonite zones developed within proximal late Precambrian granitic rocks. Gas fractions evolved at lower experimental temperatures record patterns of spectra discordance that suggest the constituent grains experienced partial, intracrystalline diffusive loss of 40Ar during a late Paleozoic, low-grade thermal overprint. A muscovite concentrate from pelitic schist beneath the allochthonous, latest Precambrian Cranberry Head granite records a 40Ar/39Ar plateau age of 318 ± 1 Ma. This is interpreted as closely dating Late Carboniferous thrust emplacement of the allochthon.

International Geology Review, Jan 12, 2023

Geoscience frontiers, May 1, 2019

Precambrian Research, Aug 1, 2022

International Geology Review, Feb 8, 2023

Global and Planetary Change, Aug 1, 2022

Journal of Asian Earth Sciences, Jul 1, 2022

Precambrian Research, Sep 1, 2021

Abstract The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the P... more Abstract The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the Proto-Tethys Ocean. To constrain this history, we present geochemical and zircon U-Pb geochronological data from a suite of metasedimentary rocks within this orogenic belt. Detrital zircons ages are clustered between 1000 and 400 Ma, with major peaks at ca. 510 Ma and 460 Ma, and minor peaks at ca. 840 Ma and 650 Ma. The age groups younger than 1000 Ma broadly overlap magmatic activity at ca. 540–420 Ma and minor magmatism at 920–540 Ma in the WKOB. The age data also reveal Early Paleozoic metamorphic basement rocks in the WKOB that were probably sourced from Kunlun terranes and blocks of Gondwanan affinity rather than the Tarim Craton. Compiled geochemical data suggest a protracted subduction setting in the WKOB in the Early Paleozoic. eHf(t) values show increasing trends at 900–740 Ma and 740–600 Ma and a distinct decreasing trend at 540–420 Ma, consistent with retreating subduction during the Neoproterozoic and advancing subduction in the Early Paleozoic. The retreating-advancing subduction cycle in the WKOB was possibly related to the opening and closure of the Proto-Tethys Ocean along the margin of Gondwana.

Geoscience frontiers, 2021

Trabajos de Geologia, Dec 31, 1988

A valonia, the largest suspect terrane in the Canadian Appalachians, originated along the Neoprot... more A valonia, the largest suspect terrane in the Canadian Appalachians, originated along the Neoproterozoic margin of Gondwana and was accreted to Laurentia by the late Ordovician. The age and character of A valonian basement is key to identifying the portion of the Gondwanan margin from which the terrane was derived and provides important constraints for Neoproterozoic paleocontinental reconstructions. Since this basement is not exposed, it must be characterized indirectly by isotopic analyses. Nd-Sm data from ca. crustally derived, 630-430 Ma felsic rocks typically record initial ~d values between 0 and +5.0 and model ages {TOM ) between 0.8 to I. I Ga, but the origin of this isotopic signature is unclear. Two early A valonian igneous complexes that were emplaced prior to the main (630•570 Ma) cycle of Neoproterozoic magmatism; the ca. 734 Ma Economy River Gneiss of mainland Nova Scotia and the ca. 675 Ma Malvems Plutonic Complex of the British Isles show non-overlapping eNd' values of + 1.29 to +4.09, and -0.11 to -2.03, respectively. Yet their TOM (998 -1194 Ma and 10431147 Ma) are almost identical and are similar to those of the main 630-570 Ma arc phase and subsequent Paleozoic tectonothennal events. This indicates that the isotopic signature is a characteristic feature of Avalonian basement and that felsic magmatism produced by peak arc activity was predominantly generated by recycling pre-existing crust. The T DM ages are interpreted to record a ca. 1.0 to 1.2 Ga tectonothennal event that fonned much of the basement upon which subsequent Neoproterozoic and Paleozoic tectonothennal activity developed. This interpretation is supported by U-Pb detrital zircon ages of 977-1223 Ma obtained from A valonian sedimentary rocks in Nova Scotia that are coeval with the main arc phase. This tectonothennal event is interpreted to reflect western-Pacific-type arc-back arc complexes fonned coevally with the Tocantins province of central Brazil. The transition to eastern Pacific-type arc activity may be related to the ca. 760 breakup of Rodinia in a manner analogous to effect of the breakup of Pangea on the tectonothennal evolution of western North America.