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3/29/2017
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The Breakup of RodiniaContinental Rifting, during or after deposition of the Pahrump Group
North American Craton“Laurentia”Australia / Antarctica
The Ediacaran(eedee-auck-corrine)
~630 – 542 my
Named after the Ediacaria Hills
of South Australia
Worm Tubes in the Noonday Dolomite
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Puddingstone:A conglomerate with colorful clasts, often
metamorphosed or meta-conglomerate
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1.1 Billion Years BP 650 Mya
Proposed reconstruction of Rodinia for 750 Ma, with orogenic belts of 1.1 Ga age highlighted in green.[Red
dots indicate 1.3–1.5 Ga granites.
Intro To Paleozoic NA
Cambrian – Permian
Time?
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The Great Unconformity exposed in the Grand Canyon. The Vishnu Schist below is ~1.7by overlain by the Tapeats Sandstone ~530my
Western North America during early Paleozoic
Paleozoic Index Fossils
More later
North America
changes it’s
latitude and
orientation in the
last ~500 my
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Some Evidence???
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The Paleo-orientation of a Continent can be determined from the
Earth’s Magnetic Field
Paleo-latitudes
can be interpreted
from Magnetic
Inclination
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Polar Reversals
Normal Polarity Reverse Polarity
Polarity Periods are called “Chrons”
Chrons can last between ~10,000 –>1,000,000 years
Reversals take around 1,000 – 10,000 years
The Brunhes-Matuyama Reversal occurred 780,000 years ago.
Bernard Brunhes (1867–1910) was a French geophysicist known for his pioneering work in paleomagnetism; 1906 discovery of geomagnetic reversal.
Motonori Matuyama 1884 – 1958) was a Japanese geophysicist who was the first to surmise that the Earth's magnetic field had undergone reversals in the past.
p
Polar Reversals createMagnetic Anomalies on the seafloor, and invertical sectionsof continental crust.
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A Geomagnetic Excursion Back to this……..
Thinner to the east, thicker to the west
Geocline Geocline
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ATTRIBUTES OF GEOCLINESModified from P. B. King
• They from as a gradual process.
• They are NOT ordinary synclinal folds.
• They are sedimentary basins that form under tectonic control.
• Subsidence is not a necessary consequence of sedimentation, but an independent process. Sedimentation can cause more subsidence.
• They occur along the margins of Continents. There is much variation in tectonic setting:1. coastal interior, continental shelf, slope and rise2. deep sea trenches, island arcs, accretionary wedges and ocean floors
• Sediments of geoclines are varied. Some have shallow water near shore sediments and some have off shore deep water sediments.
• Sediments eventually get deformed, metamorphosed and plutonized.
Western North America during early Paleozoic
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Paleozoic Geocline in California and Western US:
Miogeocline:
Eugeocline:
Klamath Mnts(McCloud and Tethyan Fauna)
Paleozoic Rocks in other provinces:
Coast Range
Transverse Range
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End of the Paleozoic:
Mountain Building in WesternUS; Docking of Sonomia
Consolidation of Continents;Formation of Pangaea
Formation of Pangaea
(300 – 250 my )
Pangaea breaks up, formation of Atlantic
Ocean and a Passive Cont Margin
(~200my present)
End of the Paleozoic:
Mountain Building in WesternUS; Docking of Sonomia
Consolidation of Continents;Formation of Pangaea
Major Mass ExtinctionHistory of thought on causes:
Worldwide Regression,(1960s, ’70s, 10 – 20 millionYears) OR… faster……?
C-12 to C-13 ratios, WillistonLake British Columbia, 1994 (8 – ~100,00 thousand years?)
C-12 = 99%C-13 = ~1%C-14 = 1 part per trillion in atmosphere
Williston Lake, British Columbia
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End of the Paleozoic:
Mountain Building in WesternUS; Docking of Sonomia
Consolidation of Continents;Formation of Pangaea
Major Mass ExtinctionHistory of thought on causes:
Worldwide Regression,(1960s, ’70s, 10 – 20 millionYears) OR… faster……?
C-12 to C-13 ratios, WillistonLake British Columbia, 1994 (8 – ~100,00 thousand years?)
Volcanism in Siberia?
Impact Event? 1) Buckyballs with He-3, 20012) Bedout Crater, May 2004
Map of the Siberian TrapsOne of the largest known volcanic eruptions in the last 500 million years
Spans the Permo-Triassic ExtinctionAmount extruded :~1 – 4 million Km3, Covers: ~2 million Km2
May have originally covered as much as 7 million Km2
Lasts for millions of years
Siberian Traps are currently 4X the area of the current Colombia River Plateau. At one point, may have been > 10X the area
End of the Paleozoic:
Consolidation of Continents;Formation of Pangaea
Mountain Building in WesternUS; Docking of Sonomia
Major Mass ExtinctionHistory of thought on causes:
Worldwide Regression,(1960s, ’70s, 10 – 20 millionYears) OR… faster……?
C-12 to C-13 ratios, WillistonLake British Columbia, 1994 (8 – ~100,00 thousand years?)
Volcanism in Siberia?
Impact Event? 1) Buckyballs with He-3, 20012) Bedout Crater, May 2004
Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia
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Researcher Luann Becker holding a bottle containing fullerenes (left) extracted from sediment at 250 my Permo-Triassic Extinction sites from Japan,
China and Hungary
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End of the Paleozoic:
Consolidation of Continents;Formation of Pangaea
Mountain Building in WesternUS; Docking of Sonomia
Major Mass ExtinctionHistory of thought on causes:
Worldwide Regression,(1960s, ’70s, 10 – 20 millionYears) OR… faster……?
C-12 to C-13 ratios, WillistonLake British Columbia, 1994 (8 – ~100,00 thousand years?)
Volcanism in Siberia?
Impact Event? 1) Buckyballs with He-3, 20012) Bedout Crater, May 2004
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