Geofizika, Vol. 15 No. 1, 1998.
Izvorni znanstveni članak
Correlated variations and periodicity of global CO2, biological mass extinctions and extra-terrestrial bolide impacts over the past 250 million years and possible geodynamical implications
R. K. Tiwari
K. N. N. Rao
Sažetak
Earth’s history has been witness to recurrently alternating phases of catastrophic evolution and dominant tectonic deformations, contractions and extension of rifting and spreading leading to quasi-cyclic changes in sedimentary environment and various earth processes. Recent studies have shown quasi-periodicities of 32 ± 2 Million years (Myr) in various endogenic (geomagnetic reversals, magmatic events, mantle convection, various tectonic activities, climate change and biological extinctions) and exogenic (impact cratering) processes indicating a remarkable kinship. We present here time series analysis of the available CO2 record over the past 250 Myr decoded from CaCO3 accumulation rates in sedimentary environment. The time series analysis reveals an intriguing evidence of a dominant periodicity of 33 ± 2 Myr which matches closely with a common “catastrophic periodicity” of 32 Myr identified in various terrestrial and extra-terrestrial records. We argue here for a common physical link among the periodic global CO2 variations, mantle convection, geomagnetic reversals, volcanism, geotectonic cycles and enhanced cometary showers. We also suggest periodic variations in CO2 as one of the possible terrestrial stimulators for the oscillating “greenhouse effect” and related climatic deterioration that result in quasi-periodic mass extinctions. Identical “catastrophic cycles” of endogenic and exogenic origin enhance the credence of their physical linkages and uphold the “concept of non-uniformitarianism” in earth’s processes.
Ključne riječi
Periodicity; global CO2; geodynamics
Hrčak ID:
17773
URI
Datum izdavanja:
1.12.1998.
Posjeta: 1.487 *