scholarly journals Proterozoic Milankovitch cycles and the history of the solar system

2018 ◽  
Vol 115 (25) ◽  
pp. 6363-6368 ◽  
Author(s):  
Stephen R. Meyers ◽  
Alberto Malinverno

The geologic record of Milankovitch climate cycles provides a rich conceptual and temporal framework for evaluating Earth system evolution, bestowing a sharp lens through which to view our planet’s history. However, the utility of these cycles for constraining the early Earth system is hindered by seemingly insurmountable uncertainties in our knowledge of solar system behavior (including Earth–Moon history), and poor temporal control for validation of cycle periods (e.g., from radioisotopic dates). Here we address these problems using a Bayesian inversion approach to quantitatively link astronomical theory with geologic observation, allowing a reconstruction of Proterozoic astronomical cycles, fundamental frequencies of the solar system, the precession constant, and the underlying geologic timescale, directly from stratigraphic data. Application of the approach to 1.4-billion-year-old rhythmites indicates a precession constant of 85.79 ± 2.72 arcsec/year (2σ), an Earth–Moon distance of 340,900 ± 2,600 km (2σ), and length of day of 18.68 ± 0.25 hours (2σ), with dominant climatic precession cycles of ∼14 ky and eccentricity cycles of ∼131 ky. The results confirm reduced tidal dissipation in the Proterozoic. A complementary analysis of Eocene rhythmites (∼55 Ma) illustrates how the approach offers a means to map out ancient solar system behavior and Earth–Moon history using the geologic archive. The method also provides robust quantitative uncertainties on the eccentricity and climatic precession periods, and derived astronomical timescales. As a consequence, the temporal resolution of ancient Earth system processes is enhanced, and our knowledge of early solar system dynamics is greatly improved.

Author(s):  
D.E. Brownlee ◽  
A.L. Albee

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.


2016 ◽  
Vol 50 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Tomohiro Usui ◽  
Audrey Bouvier ◽  
Justin I. Simon ◽  
Noriko Kita

2018 ◽  
Author(s):  
Gerilyn S. Soreghan ◽  
◽  
Michael J. Soreghan ◽  
Nicholas G. Heavens

Nature ◽  
2019 ◽  
Vol 569 (7754) ◽  
pp. 85-88 ◽  
Author(s):  
Imre Bartos ◽  
Szabolcs Marka

2021 ◽  
pp. 163-194
Author(s):  
Dante S. Lauretta ◽  
Heather L. Enos ◽  
Anjani T. Polit ◽  
Heather L. Roper ◽  
Catherine W.V. Wolner

2008 ◽  
Author(s):  
S. Itoh ◽  
H. Yurimoto ◽  
Takuma Suda ◽  
Takaya Nozawa ◽  
Akira Ohnishi ◽  
...  

2014 ◽  
Vol 127 ◽  
pp. 57-66 ◽  
Author(s):  
Thomas Mueller ◽  
E. Bruce Watson ◽  
Dustin Trail ◽  
Michael Wiedenbeck ◽  
James Van Orman ◽  
...  

2006 ◽  
Vol 70 (18) ◽  
pp. A29
Author(s):  
J.A. Baker ◽  
M. Bizzarro

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