Putting All the Data Together Makes a More Complete History – #365papers – 2017 – 77

#365papers for March 18, 2017

Feakins, Levin, Liddy, Sieracki, Eglinton, and Bonnefille, 2017, Northeast African vegetation change over 12 m.y.: Geology, v. 41, p. 295-298.

What’s it about?

The authors combine pollen and isotopic data from fossil leaf waxes from an ocean core with soil carbonate data from northeast Africa to better understand the origin and composition of grasslands in northeast Africa over the last 12 million years. Continue reading

Global Warming; Shrinking Mammals – #365papers – 2017 – 76

#365papers for March 17, 2017

D’Ambrosia, Clyde, Fricke, Gringerich, Abels, 2017, Repetitive mammalian dwarfing during ancient greenhouse warming events: Science Advances, v. 3, e1601430.

What’s it about?

Rapid global warming in Earth’s past had occurred more than once. The most commonly studied episode occurred 55 million years ago, at the boundary between the Paleocene and Eocene epochs (Paleocene Eocene Thermal Maximum, PETM). Several other episodes have happened, including the ETM2 and H2 episodes which are discussed in this paper.

Dwarfing of mammalian species has been documented at the PETM. This paper shows dwarfing of mammals also occurred at the ETM2. Continue reading

How Soil Carbonate Can Tell Us About Climate – #365papers – 2017 – 75

#365papers for March 16, 2017

Cerling, T.E., 1984, The stable isotopic composition of modern soil carbonate and its relationship to climate: Earth and Planetary Science Letters, v. 71, p. 229-240.

What’s it about?

This paper discusses in detail how isotopes of carbon and oxygen in carbonate minerals that form in soils are related to that of plant biomass (carbon) or local precipitation (oxygen). Continue reading

Lakes Come and Go, 50 Million Years Ago – #365papers – 2017 – 69

#365papers for March 10, 2017

Davis, Wiegand, Carroll, and Chamberlain, 2008, The effect of dreainage reorganization on paleoaltimetry studies: An example from the Paleogene Laramide foreland: Earth and Planetary Science Letters, v. 275, p. 258-268.

What’s it about?

The authors use isotopes of carbon, oxygen, and strontium, plus relative abundances of strontium and calcium in lake deposits to interpret water sources, connectivity of lakes, and general environmental parameters for the Uinta Basin during the Eocene (~55-~43 million years ago). Continue reading

The Middle Eocene Climatic Optimum in the Northern Hemisphere – #365papers – 2017 – 67

#365papers for March 8, 2017

Jovane, Florindo Coccioni, Dianares-Turell, Marsili, Monechi, Roberts, Sprovieri, 2007, The middle Eocene climatic optimum event in the Contessa Highway section, Umbrian Apennines, Italy: GSA Bulletin, v. 119, p. 413-427.

What’s it about?

This paper like others I’ve read recently discusses the abundance of single-celled organisms in the ocean called foraminifera (forams). The overall abundance of different species plus isotopic analysis of the fossils themselves can provide insights about climate during the middle Eocene. Continue reading

Paleogene Antarctic ocean circulation from isotopes – #365papers – 2017 – 66

#365papers for March 7, 2017

Kennett and Stott, 1990 Proteus and Proto-Oceanus: ancestral paleogene oceans as revealed from Antarctic stable isotopic results; ODP Leg 113: Proceedings of the Ocean Drilling Programs, Scientific Results, v. 113, p. 865-880.

What’s it about?

These are the published results of an ocean drilling cruise that took place in Antarctica in the late 1980’s. A core from the ocean floor was drilled and various parts of it were studied. This paper discusses geochemical results from the skeletons (tests) of single-celled organisms called foraminifera (forams) found throughout the core. From these results, the authors discuss deep ocean currents from millions of years ago. Continue reading

The Paleocene-Eocene boundary in deep ocean foraminifera – #365papers – 2017 – 65

#365papers for March 6, 2017

Thomas and Shackleton, 1996, The Paleocene-Eocene benthic forminiferal extinction and stable isotope anomalies, in Knox, Corfield, Dunay, eds., Correlation of the Early Paleogene in Northwest Europe: Geological Society Special Publication n. 101, p. 401-441.

What’s it about?

This paper examines the abundance and geochemistry of single-celled organisms called foraminiferans (forams) that were living in the oceans around 55 million years ago. Forams are still present today worldwide. They make little tiny calcite skeletons (called tests) that can be used to identify the species and then can be analyzed.

Using these foram skeletons, the authors identified the many species that lived in the ocean before and after the Paleocene-Eocene boundary and recognized some extinctions associated with the boundary. With geochemical analysis, they showed that there are some significant anomalies (rapid, unexpected changes) at the Paleocene-Eocene boundary. Continue reading

Knowing a Snail’s Diet from the Chemistry of its Shell – #3650papers – 2017 – 62

#365papers for March 3, 2017

Prendergast, Stevens, Hill, Hunt, O’Connell, and Barker, 2015, Carbon isotope signatures from land snail shells: Implications for palaeovegetation reconstruction in the eastern Mediterranean: Quaternary International, in press.

What’s it about?

This paper discusses the use of carbon isotopes in the shells of land snails to interpret what the snails were eating. To do this, they studied wild snails for which they could also measure the carbon isotopes of potential food sources. Continue reading

Recognizing What Was Once a Safe Space Using Fossil Snails – #365papers – 2017 – 59

#365papers for February 28, 2017

Prendergast, Stevens, O’Connell, Hill, Hunt and Barker, 2016, A late Pleistocene refugium in Mediterranean North Africa? Palaeoenvironmental reconstruction from stable isotope analyses of land snail shells (Haua Fteah, Libya): Quaternary Science Reviews, v. 139, p. 94-109.

What’s it about?

There was a time in early human history when northern Africa grew arid, making life rather challenging for people. This paper is about an area where the aridity did not have such an impact, making a safe refugium for people to wait it out. The evidence that there was, in fact, a ‘safe space’ comes from isotopic analysis of fossil snails. Continue reading

The Clean SWEEP of the Rocky Mountains – #365papers – 2017 – 50

#365papers for February 19, 2017

Chamberlain, Mix, Mulch, Hren, Kent-Corson, Davis, Horton, and Graham, 2012, The Cenozoic climatic and topographic evolution of the western North American cordillera: American Journal of Science, v. 312, p. 213-262.

What’s it about?

This paper uses a compilation of new and previously published oxygen stable isotope data from all over the Rocky Mountain region to understand the timing and uplift pattern of the Rocky Mountains. It seems that the Rocky Mountains first rose to the north, then grew southward. Continue reading