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Papers by colin summerhayes

Brazilian Journal of Geology, 1976

The Holocene, Aug 4, 2016

The recent re-evaluation of sunspot data by Clette et al. strongly suggests that the total solar ... more The recent re-evaluation of sunspot data by Clette et al. strongly suggests that the total solar irradiance (TSI) values for the late 20th century were (apart from 1960) not significantly different from those of the periods of sunspot maxima in the 1780s and the 1840s–1860s in the latter part of the ‘Little Ice Age’. In effect, the re-evaluation removed the previously supposed sunspot maximum of the ‘modern’ period. That means that the supposed recovery of TSI levels to values significantly higher in the late 20th century than those of the ‘Medieval Quiet (or Warm) Period’ (Figure 1 of Bradley et al., 2016) must be an artefact of the solar data. Orbital data suggest that the northern hemisphere cooled significantly over the past 2000 years, a trend confirmed by global temperature proxies. Variations about that trend were driven by small variations in sunspot activity that led to the warmth of the ‘Medieval Quiet (Warm) Period’ and the subsequent cooling of the ‘Little Ice Age’. In fact, the ‘Little Ice Age’ contained several short warm periods when sunspots were at a maximum. It seems highly likely given the new sunspot calibration that the mid- to late 20th century warming was yet another of these ‘Little Ice Age’ warm episodes (e.g. no different from that in 1780) superimposed on which was a growing additional warming supplied by expanding emissions of greenhouses gases.

New Zealand Journal of Geology and Geophysics, May 1, 1975

Phosphate deposits which apparently formed during the Miocene climatic optimum are widespread on ... more Phosphate deposits which apparently formed during the Miocene climatic optimum are widespread on the Chatham Rise and Camp bell Plateau, and on seamounts in the north Tasman Sea. They formed under oxidising conditions by the phosphatisation of older or contemporaneous foraminiferal oozes (Campbell Plateau and Chatham Rise) and coral limestones (Tasman Sea). The phosphorites of the rise and plateau were formed where current activity was sufficiently strong to prevent normal sedimentation, and now form lag deposits. After the Miocene, phosphorite formation ceased and was followed by manganese oxide deposition where conditions were highly oxidising on the eastern Campbell Plateau and north Tasman seamounts, and by glauconite formation in the much less oxidising environments of the western Campbell Plateau and the Chat ham Rise. The manganese deposits are not volcanogenic, as was formerly thought, but formed by slow precipitation from well oxygenated sea water.

John Wiley & Sons, Ltd eBooks, Aug 17, 2015

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Dynamics of Atmospheres and Oceans, 1993

U.S. Government Printing Office eBooks, Sep 1, 1981

Economic geology and the bulletin of the Society of Economic Geologists, Oct 1, 1970

Journal of the Geological Society, Mar 1, 1990

... Page 4. 318 C . P. SUMMERHAYES 11.7"C for the Maastrichtian. ... Gardar Drift, then, per... more ... Page 4. 318 C . P. SUMMERHAYES 11.7"C for the Maastrichtian. ... Gardar Drift, then, perhaps counter-intuitively, is primarily an interglacial construction. Shackleton talked aboutastronomical calibration of climatic variability in the Late Neogene. ...

Oxford University Press eBooks, Jan 19, 2023

U.S. Government Printing Office eBooks, Sep 1, 1981

This synthesis of organic geochemical studies from Leg 63 was designed to answer fundamental ques... more This synthesis of organic geochemical studies from Leg 63 was designed to answer fundamental questions about the source, deposition, preservation, and alteration of organic matter off California and Baja California. The answers to these questions help to determine the extent and degree of influence of paleoenvironmental factors, the understanding of which was among the main objectives of drilling on this leg. The organic matter is mostly marine, and was deposited as pelagic sediment. Terrigenous components are abundant in the deep sea fan at Site 471, and in the upper Pliocene and Quaternary rocks and sediments of the California Borderland. Total organic matter (TOC) is highest in the upper Miocene to lower Pliocene rocks and sediments at Site 467, and in the middle Miocene rocks and sediments at Site 468, probably as a response to increased upwelling and high productivity, accompanied by depletion of oxygen in the oxygen minimum zone. Deeper water sites contain little organic matter, and do not exhibit a record of changes in surface circulation. All of the drilled sections are thermally immature, but light hydrocarbons are being generated in small amounts deep at Site 467. Light hydrocarbons that were probably generated in the vicinity of a sill at the bottom of Hole 471 have migrated in substantial amounts into the overlying section.

Brazilian Journal of Geology, 1976

The Holocene, Aug 4, 2016

The recent re-evaluation of sunspot data by Clette et al. strongly suggests that the total solar ... more The recent re-evaluation of sunspot data by Clette et al. strongly suggests that the total solar irradiance (TSI) values for the late 20th century were (apart from 1960) not significantly different from those of the periods of sunspot maxima in the 1780s and the 1840s–1860s in the latter part of the ‘Little Ice Age’. In effect, the re-evaluation removed the previously supposed sunspot maximum of the ‘modern’ period. That means that the supposed recovery of TSI levels to values significantly higher in the late 20th century than those of the ‘Medieval Quiet (or Warm) Period’ (Figure 1 of Bradley et al., 2016) must be an artefact of the solar data. Orbital data suggest that the northern hemisphere cooled significantly over the past 2000 years, a trend confirmed by global temperature proxies. Variations about that trend were driven by small variations in sunspot activity that led to the warmth of the ‘Medieval Quiet (Warm) Period’ and the subsequent cooling of the ‘Little Ice Age’. In fact, the ‘Little Ice Age’ contained several short warm periods when sunspots were at a maximum. It seems highly likely given the new sunspot calibration that the mid- to late 20th century warming was yet another of these ‘Little Ice Age’ warm episodes (e.g. no different from that in 1780) superimposed on which was a growing additional warming supplied by expanding emissions of greenhouses gases.

New Zealand Journal of Geology and Geophysics, May 1, 1975

Phosphate deposits which apparently formed during the Miocene climatic optimum are widespread on ... more Phosphate deposits which apparently formed during the Miocene climatic optimum are widespread on the Chatham Rise and Camp bell Plateau, and on seamounts in the north Tasman Sea. They formed under oxidising conditions by the phosphatisation of older or contemporaneous foraminiferal oozes (Campbell Plateau and Chatham Rise) and coral limestones (Tasman Sea). The phosphorites of the rise and plateau were formed where current activity was sufficiently strong to prevent normal sedimentation, and now form lag deposits. After the Miocene, phosphorite formation ceased and was followed by manganese oxide deposition where conditions were highly oxidising on the eastern Campbell Plateau and north Tasman seamounts, and by glauconite formation in the much less oxidising environments of the western Campbell Plateau and the Chat ham Rise. The manganese deposits are not volcanogenic, as was formerly thought, but formed by slow precipitation from well oxygenated sea water.

John Wiley & Sons, Ltd eBooks, Aug 17, 2015

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Oxford University Press eBooks, Feb 20, 2023

Dynamics of Atmospheres and Oceans, 1993

U.S. Government Printing Office eBooks, Sep 1, 1981

Economic geology and the bulletin of the Society of Economic Geologists, Oct 1, 1970

Journal of the Geological Society, Mar 1, 1990

... Page 4. 318 C . P. SUMMERHAYES 11.7"C for the Maastrichtian. ... Gardar Drift, then, per... more ... Page 4. 318 C . P. SUMMERHAYES 11.7"C for the Maastrichtian. ... Gardar Drift, then, perhaps counter-intuitively, is primarily an interglacial construction. Shackleton talked aboutastronomical calibration of climatic variability in the Late Neogene. ...

Oxford University Press eBooks, Jan 19, 2023

U.S. Government Printing Office eBooks, Sep 1, 1981

This synthesis of organic geochemical studies from Leg 63 was designed to answer fundamental ques... more This synthesis of organic geochemical studies from Leg 63 was designed to answer fundamental questions about the source, deposition, preservation, and alteration of organic matter off California and Baja California. The answers to these questions help to determine the extent and degree of influence of paleoenvironmental factors, the understanding of which was among the main objectives of drilling on this leg. The organic matter is mostly marine, and was deposited as pelagic sediment. Terrigenous components are abundant in the deep sea fan at Site 471, and in the upper Pliocene and Quaternary rocks and sediments of the California Borderland. Total organic matter (TOC) is highest in the upper Miocene to lower Pliocene rocks and sediments at Site 467, and in the middle Miocene rocks and sediments at Site 468, probably as a response to increased upwelling and high productivity, accompanied by depletion of oxygen in the oxygen minimum zone. Deeper water sites contain little organic matter, and do not exhibit a record of changes in surface circulation. All of the drilled sections are thermally immature, but light hydrocarbons are being generated in small amounts deep at Site 467. Light hydrocarbons that were probably generated in the vicinity of a sill at the bottom of Hole 471 have migrated in substantial amounts into the overlying section.