Birger Rasmussen - Academia.edu (original) (raw)

Uploads

Papers by Birger Rasmussen

Research paper thumbnail of Hydrothermal hydrocarbon generation in 3.5 Ga basalt-hosted seafloor vent systems, North Pole Dome, Pilbara Craton, Australia

Research paper thumbnail of U-Pb dating reveals multiple Paleoproterozoic orogenic events (Hamersley orogenic cycle) along the southern Pilbara margin (Australia) spanning the onset of atmospheric oxygenation

Geology, May 12, 2022

Xenotime and monazite were analysed for U-Pb dating with the Sensitive High-Resolution Ion MicroP... more Xenotime and monazite were analysed for U-Pb dating with the Sensitive High-Resolution Ion MicroProbe (SHRIMP-II) instrument at the John De Laeter Centre, Perth, Western Australia. Grains were identified in polished thin sections, and 3 mm diameter plugs were extracted from the thin sections with a hollow-core rotary drill and mounted in 25 mm diameter epoxy discs. The mounts were cleaned and gold coated before each analytical session. Xenotime and monazite standards were set into separate mounts and gold coated simultaneously with sample mounts. Standard and sample mounts were loaded together into the SHRIMP for concurrent analysis during each of the four analytical sessions. Instrument setup followed protocols for small-spot, in-situ analysis of xenotime and monazite developed in . A primary beam of O2 -ions was focused through a 50 µm Kohler aperture to produce an oval 10 µm wide spot on the sample surface with a current of 0.3 nA. The secondary ion system was focused through a 100 µm collector slit onto an electron multiplier to produce mass peaks with flat tops and a mass resolution of >5400 in all sessions. Background counts from scattered ions were reduced using a flight retardation lens, which is known to cause slight session-dependent instrumental mass fractionation (IMF) of Pb isotopes . IMF corrections were applied to all analyses. Data were collected in sets of 8 scans, with standard xenotime or monazite analysed every 4-6 sample analyses. Count times per scan for Pb isotopes 204, background position 204.045, 206, 207 and 208 were 10s, 10s, 10s, 30s and 10s, respectively. Monazite was analysed with a 13-peak run table as defined in , which includes mass stations for the estimation of La, Ce and Nd (REEPO2 + ), and Y (YCeO + ). Measurements on monazite standards FRENCH, Z2234 and Z2908 (see

Research paper thumbnail of Rhabdophane Th-Pb ages indicate reactivation of Mesoarchean structures in west Pilbara Craton during breakup of Greater India and Australia-Antarctica

Research paper thumbnail of The Mangaroon Orogeny: Synchronous c. 1.7 Ga magmatism and low-P, high-T metamorphism in the West Australian Craton

Precambrian Research, Oct 1, 2019

Research paper thumbnail of Neoproterozoic 40Ar/39Ar mica ages mark the termination of a billion years of intraplate reworking in the Capricorn Orogen, Western Australia

Precambrian Research, Jun 1, 2018

Research paper thumbnail of Low‐Fe(III) Greenalite Was a Primary Mineral From Neoarchean Oceans

Geophysical Research Letters, Apr 2, 2018

Research paper thumbnail of The Glenburgh orogeny as a record of Paleoproterozoic continent-continent collision

Research paper thumbnail of Zirconolite and xenotime U–Pb age constraints on the emplacement of the Golden Mile Dolerite sill and gold mineralization at the Mt Charlotte mine, Eastern Goldfields Province, Yilgarn Craton, Western Australia

Contributions to Mineralogy and Petrology, Nov 6, 2008

Research paper thumbnail of Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor

Chemical Geology, Feb 1, 2023

Research paper thumbnail of Tectonic fluid expulsion: U-Pb evidence for punctuated hydrothermal fluid flow and hydraulic fracturing during orogenesis

Earth and Planetary Science Letters, Feb 1, 2023

Research paper thumbnail of Eocene animal trace fossils in 1.7-billion-year-old metaquartzites

Proceedings of the National Academy of Sciences of the United States of America, Sep 27, 2021

Research paper thumbnail of Young ores in old rocks: Proterozoic iron mineralisation in Mesoarchean banded iron formation, northern Pilbara Craton, Australia

Ore Geology Reviews, Oct 1, 2017

Research paper thumbnail of Dating fluid flow and Mississippi Valley type base-metal mineralization in the Paleoproterozoic Earaheedy Basin, Western Australia

Precambrian Research, Aug 1, 2012

Abstract The ages of deposition and metamorphism of low-grade Precambrian metasedimentary sequenc... more Abstract The ages of deposition and metamorphism of low-grade Precambrian metasedimentary sequences can be difficult to define in the absence of interlayered volcanogenic rocks. Monazite and xenotime can grow at temperatures below 400 °C and can give vital evidence for the timing of diagenesis, hydrothermal fluid flow, and low-grade deformation and metamorphism in Precambrian basins. The histories of sedimentary basins in the eastern Capricorn Orogen of the West Australian Craton are generally poorly constrained. However, sandstones and siltstones of the basal Yelma Formation in the Earaheedy Basin contain authigenic monazite and xenotime associated with sulphide minerals related to Mississippi Valley Type base-metal mineralization hosted within carbonate of the overlying Sweetwaters Well Member. In the Teague area, within the Earaheedy Basin, siliciclastic rocks overlying granites of the Yilgarn Craton contain authigenic monazite that gives an in situ SHRIMP 207 Pb/ 206 Pb age of 1811 ± 13 Ma. Monazite in weathered sandstones and siltstones of the Cano secondary Pb deposit on Magellan Hill, overlying the Yerrida Basin, gives an indistinguishable age of 1815 ± 13 Ma. The Cano monazite is interpreted to have been intergrown with primary sulphide minerals and therefore to record the age of mineralization. Xenotime outgrowths on detrital zircons from Cano have high common Pb but define an isochron with an age of 1832 ± 36 Ma. The isochron is co-linear with Pb isotope ratios from Pb ore at Magellan, suggesting that xenotime growth is also related to mineralization. The timing of fluid flow is synchronous with the 1820–1770 Ma Capricorn Orogeny, and is the first evidence for activity of this age in the eastern part of the Capricorn Orogen. The age of mineralization provides a firm minimum age for the Yelma Formation, and constrains its deposition to between ∼2.0 Ga, the youngest age of detrital zircons, and the mineralization age.

Research paper thumbnail of In situ SHRIMP U–Pb dating of monazite integrated with petrology and textures: Does bulk composition control whether monazite forms in low-Ca pelitic rocks during amphibolite facies metamorphism?

Geochimica et Cosmochimica Acta, Jun 1, 2006

Research paper thumbnail of Deposition of 1.88-billion-year-old iron formations as a consequence of rapid crustal growth

Research paper thumbnail of Archaean gold mineralization synchronous with late cratonization of the Western Dharwar Craton, India: 2.52 Ga U–Pb ages of hydrothermal monazite and xenotime in gold deposits

Mineralium Deposita, Jan 12, 2011

Research paper thumbnail of Correlation of Paleoproterozoic glaciations based on U–Pb zircon ages for tuff beds in the Transvaal and Huronian Supergroups

Earth and Planetary Science Letters, Nov 1, 2013

Research paper thumbnail of Exploring Iron Silicate Precursors of Ancient Iron Formations through Rock Record, Laboratory and Field Analogue Investigations

AGU Fall Meeting Abstracts, Dec 1, 2016

Research paper thumbnail of Organic carbon generation in 3.5-billion-year-old basalt-hosted seafloor hydrothermal vent systems

Science Advances, Feb 1, 2023

Carbon is the key element of life, and its origin in ancient sedimentary rocks is central to ques... more Carbon is the key element of life, and its origin in ancient sedimentary rocks is central to questions about the emergence and early evolution of life. The oldest well-preserved carbon occurs with fossil-like structures in 3.5-billion-year-old black chert. The carbonaceous matter, which is associated with hydrothermal chert-barite vent systems originating in underlying basaltic-komatiitic lavas, is thought to be derived from microbial life. Here, we show that 3.5-billion-year-old black chert vein systems from the Pilbara Craton, Australia contain abundant residues of migrated organic carbon. Using younger analogs, we argue that the black cherts formed during precipitation from silica-rich, carbon-bearing hydrothermal fluids in vein systems and vent-proximal seafloor sediments. Given the volcanic setting and lack of organic-rich sediments, we speculate that the vent-mound systems contain carbon derived from rock-powered organic synthesis in the underlying mafic-ultramafic lavas, providing a glimpse of a prebiotic world awash in terrestrial organic compounds.

Research paper thumbnail of Reexamination of 2.5-Ga “whiff” of oxygen interval points to anoxic ocean before GOE

Science Advances, Jan 7, 2022

Research paper thumbnail of Hydrothermal hydrocarbon generation in 3.5 Ga basalt-hosted seafloor vent systems, North Pole Dome, Pilbara Craton, Australia

Research paper thumbnail of U-Pb dating reveals multiple Paleoproterozoic orogenic events (Hamersley orogenic cycle) along the southern Pilbara margin (Australia) spanning the onset of atmospheric oxygenation

Geology, May 12, 2022

Xenotime and monazite were analysed for U-Pb dating with the Sensitive High-Resolution Ion MicroP... more Xenotime and monazite were analysed for U-Pb dating with the Sensitive High-Resolution Ion MicroProbe (SHRIMP-II) instrument at the John De Laeter Centre, Perth, Western Australia. Grains were identified in polished thin sections, and 3 mm diameter plugs were extracted from the thin sections with a hollow-core rotary drill and mounted in 25 mm diameter epoxy discs. The mounts were cleaned and gold coated before each analytical session. Xenotime and monazite standards were set into separate mounts and gold coated simultaneously with sample mounts. Standard and sample mounts were loaded together into the SHRIMP for concurrent analysis during each of the four analytical sessions. Instrument setup followed protocols for small-spot, in-situ analysis of xenotime and monazite developed in . A primary beam of O2 -ions was focused through a 50 µm Kohler aperture to produce an oval 10 µm wide spot on the sample surface with a current of 0.3 nA. The secondary ion system was focused through a 100 µm collector slit onto an electron multiplier to produce mass peaks with flat tops and a mass resolution of >5400 in all sessions. Background counts from scattered ions were reduced using a flight retardation lens, which is known to cause slight session-dependent instrumental mass fractionation (IMF) of Pb isotopes . IMF corrections were applied to all analyses. Data were collected in sets of 8 scans, with standard xenotime or monazite analysed every 4-6 sample analyses. Count times per scan for Pb isotopes 204, background position 204.045, 206, 207 and 208 were 10s, 10s, 10s, 30s and 10s, respectively. Monazite was analysed with a 13-peak run table as defined in , which includes mass stations for the estimation of La, Ce and Nd (REEPO2 + ), and Y (YCeO + ). Measurements on monazite standards FRENCH, Z2234 and Z2908 (see

Research paper thumbnail of Rhabdophane Th-Pb ages indicate reactivation of Mesoarchean structures in west Pilbara Craton during breakup of Greater India and Australia-Antarctica

Research paper thumbnail of The Mangaroon Orogeny: Synchronous c. 1.7 Ga magmatism and low-P, high-T metamorphism in the West Australian Craton

Precambrian Research, Oct 1, 2019

Research paper thumbnail of Neoproterozoic 40Ar/39Ar mica ages mark the termination of a billion years of intraplate reworking in the Capricorn Orogen, Western Australia

Precambrian Research, Jun 1, 2018

Research paper thumbnail of Low‐Fe(III) Greenalite Was a Primary Mineral From Neoarchean Oceans

Geophysical Research Letters, Apr 2, 2018

Research paper thumbnail of The Glenburgh orogeny as a record of Paleoproterozoic continent-continent collision

Research paper thumbnail of Zirconolite and xenotime U–Pb age constraints on the emplacement of the Golden Mile Dolerite sill and gold mineralization at the Mt Charlotte mine, Eastern Goldfields Province, Yilgarn Craton, Western Australia

Contributions to Mineralogy and Petrology, Nov 6, 2008

Research paper thumbnail of Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor

Chemical Geology, Feb 1, 2023

Research paper thumbnail of Tectonic fluid expulsion: U-Pb evidence for punctuated hydrothermal fluid flow and hydraulic fracturing during orogenesis

Earth and Planetary Science Letters, Feb 1, 2023

Research paper thumbnail of Eocene animal trace fossils in 1.7-billion-year-old metaquartzites

Proceedings of the National Academy of Sciences of the United States of America, Sep 27, 2021

Research paper thumbnail of Young ores in old rocks: Proterozoic iron mineralisation in Mesoarchean banded iron formation, northern Pilbara Craton, Australia

Ore Geology Reviews, Oct 1, 2017

Research paper thumbnail of Dating fluid flow and Mississippi Valley type base-metal mineralization in the Paleoproterozoic Earaheedy Basin, Western Australia

Precambrian Research, Aug 1, 2012

Abstract The ages of deposition and metamorphism of low-grade Precambrian metasedimentary sequenc... more Abstract The ages of deposition and metamorphism of low-grade Precambrian metasedimentary sequences can be difficult to define in the absence of interlayered volcanogenic rocks. Monazite and xenotime can grow at temperatures below 400 °C and can give vital evidence for the timing of diagenesis, hydrothermal fluid flow, and low-grade deformation and metamorphism in Precambrian basins. The histories of sedimentary basins in the eastern Capricorn Orogen of the West Australian Craton are generally poorly constrained. However, sandstones and siltstones of the basal Yelma Formation in the Earaheedy Basin contain authigenic monazite and xenotime associated with sulphide minerals related to Mississippi Valley Type base-metal mineralization hosted within carbonate of the overlying Sweetwaters Well Member. In the Teague area, within the Earaheedy Basin, siliciclastic rocks overlying granites of the Yilgarn Craton contain authigenic monazite that gives an in situ SHRIMP 207 Pb/ 206 Pb age of 1811 ± 13 Ma. Monazite in weathered sandstones and siltstones of the Cano secondary Pb deposit on Magellan Hill, overlying the Yerrida Basin, gives an indistinguishable age of 1815 ± 13 Ma. The Cano monazite is interpreted to have been intergrown with primary sulphide minerals and therefore to record the age of mineralization. Xenotime outgrowths on detrital zircons from Cano have high common Pb but define an isochron with an age of 1832 ± 36 Ma. The isochron is co-linear with Pb isotope ratios from Pb ore at Magellan, suggesting that xenotime growth is also related to mineralization. The timing of fluid flow is synchronous with the 1820–1770 Ma Capricorn Orogeny, and is the first evidence for activity of this age in the eastern part of the Capricorn Orogen. The age of mineralization provides a firm minimum age for the Yelma Formation, and constrains its deposition to between ∼2.0 Ga, the youngest age of detrital zircons, and the mineralization age.

Research paper thumbnail of In situ SHRIMP U–Pb dating of monazite integrated with petrology and textures: Does bulk composition control whether monazite forms in low-Ca pelitic rocks during amphibolite facies metamorphism?

Geochimica et Cosmochimica Acta, Jun 1, 2006

Research paper thumbnail of Deposition of 1.88-billion-year-old iron formations as a consequence of rapid crustal growth

Research paper thumbnail of Archaean gold mineralization synchronous with late cratonization of the Western Dharwar Craton, India: 2.52 Ga U–Pb ages of hydrothermal monazite and xenotime in gold deposits

Mineralium Deposita, Jan 12, 2011

Research paper thumbnail of Correlation of Paleoproterozoic glaciations based on U–Pb zircon ages for tuff beds in the Transvaal and Huronian Supergroups

Earth and Planetary Science Letters, Nov 1, 2013

Research paper thumbnail of Exploring Iron Silicate Precursors of Ancient Iron Formations through Rock Record, Laboratory and Field Analogue Investigations

AGU Fall Meeting Abstracts, Dec 1, 2016

Research paper thumbnail of Organic carbon generation in 3.5-billion-year-old basalt-hosted seafloor hydrothermal vent systems

Science Advances, Feb 1, 2023

Carbon is the key element of life, and its origin in ancient sedimentary rocks is central to ques... more Carbon is the key element of life, and its origin in ancient sedimentary rocks is central to questions about the emergence and early evolution of life. The oldest well-preserved carbon occurs with fossil-like structures in 3.5-billion-year-old black chert. The carbonaceous matter, which is associated with hydrothermal chert-barite vent systems originating in underlying basaltic-komatiitic lavas, is thought to be derived from microbial life. Here, we show that 3.5-billion-year-old black chert vein systems from the Pilbara Craton, Australia contain abundant residues of migrated organic carbon. Using younger analogs, we argue that the black cherts formed during precipitation from silica-rich, carbon-bearing hydrothermal fluids in vein systems and vent-proximal seafloor sediments. Given the volcanic setting and lack of organic-rich sediments, we speculate that the vent-mound systems contain carbon derived from rock-powered organic synthesis in the underlying mafic-ultramafic lavas, providing a glimpse of a prebiotic world awash in terrestrial organic compounds.

Research paper thumbnail of Reexamination of 2.5-Ga “whiff” of oxygen interval points to anoxic ocean before GOE

Science Advances, Jan 7, 2022