Thursday, June 27, 2013

Changes to Sedimentation Systems Through Deep Time (Late Archean to Phanerozoic)

Secular changes in sedimentation systems and sequence stratigraphy

Authors:

1. Patrick G. Eriksson (a)
2. Santanu Banerjee (b)
3. Octavian Catuneanu (c)
4. Patricia L. Corcoran (d)
5. Kenneth A. Eriksson (e)
6. Eric E. Hiatt (f)
7. Marc Laflamme (g, 1)
8. Nils Lenhardt (a)
9. Darrel G.F. Long (h)
10. Andrew D. Miall (i)
11. Michael V. Mints (j)
12. Peir K. Pufahl (k)
13. Subir Sarkar (l)
14. Edward L. Simpson (m)
15. George E. Williams (n)

Affiliations:

a. Department of Geology, University of Pretoria, Pretoria 0002, South Africa

b. Department of Earth Sciences, IIT Bombay, Pawai, Mumbai 400 076, India

c. Department of Earth and Atmospheric Sciences, 1–26 Earth Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E3

d. Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7

e. Department of Geological Sciences, Virginia Tech., Blacksburg, VA 24061, USA

f. Geology Department, University of Wisconsin, Oshkosh, Oshkosh, Wisconsin, 54901-8649, USA

g. Department of Paleobiology, Smithsonian Institution, Washington DC, 20013-7012, USA

h. Department of Earth Sciences, Laurentian University, Sudbury, Ontario, Canada P3E 2C6

i. Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario, Canada M5S 3B1

j. Laboratory of the Early Precambrian Tectonics, Geological Institute of the Russian Academy of Sciences, Pyzhevsky Street 7, 109017 Moscow, Russia

k. Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6

l. Department of Geological Sciences, Jadavpur University, Kolkata 700 032, India

m. Department of Physical Sciences, Kutztown University of Pennsylvania, Kutztown, PA 19530, USA

n. Geology and Geophysics, University of Adelaide, Adelaide, SA 5005, Australia

Abstract:

The ephemeral nature of most sedimentation processes and the fragmentary character of the sedimentary record are of first-order importance. Despite a basic uniformity of external controls on sedimentation resulting in markedly similar lithologies, facies, facies associations and depositional elements within the rock record across time, there are a number of secular changes, particularly in rates and intensities of processes that resulted in contrasts between preserved Precambrian and Phanerozoic successions. Secular change encompassed (1) variations in mantle heat, rates of plate drift and of continental crustal growth, the gravitational effects of the Moon, and in rates of weathering, erosion, transport, deposition and diagenesis; (2) a decreasing planetary rotation rate over time; (3) no vegetation in the Precambrian, but prolific microbial mats, with the opposite pertaining to the Phanerozoic; (4) the long-term evolution of the hydrosphere–atmosphere–biosphere system. A relatively abrupt and sharp turning point was reached in the Neoarchaean, with spikes in mantle plume flux and tectonothermal activity and possibly concomitant onset of the supercontinent cycle. Substantial and irreversible change occurred subsequently in the Palaeoproterozoic, whereby the dramatic change from reducing to oxidizing volcanic gases ushered in change to an oxic environment, to be followed at ca. 2.4–2.3 Ga by the “Great Oxidation Event” (GOE); rise in atmospheric oxygen was accompanied by expansion of oxygenic photosynthesis in the cyanobacteria. A possible global tectono-thermal “slowdown” from ca. 2.45–2.2 Ga may have separated a preceding plate regime which interacted with a higher energy mantle from a ca. 2.2–2.0 Ga Phanerozoic-style plate tectonic regime; the “slowdown” period also encompassed the first known global-scale glaciation and overlapped with the GOE. While large palaeodeserts emerged from ca. 2.0–1.8 Ga, possibly associated with the evolution of the supercontinent cycle, widespread euxinia by ca. 1.85 Ga ushered in the “boring billion” year period. A second time of significant and irreversible change, in the Neoproterozoic, saw a second major oxidation event and several low palaeolatitude Cryogenian (740–630 Ma) glaciations. With the veracity of the “Snowball Earth” model for Neoproterozoic glaciation being under dispute, genesis of Pre-Ediacaran low-palaeolatitude glaciation remains enigmatic. Ediacaran (635–542 Ma) glaciation with a wide palaeolatitudinal range contrasts with the circum-polar nature of Phanerozoic glaciation. The observed change from low latitude to circum-polar glaciation parallels advent and diversification of the Metazoa and the Neoproterozoic oxygenation (ca. 580 Ma), and was succeeded by the Ediacaran–Cambrian transition which ushered in biomineralization, with all its implications for the chemical sedimentary record.

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