A record of the extraterrestrial 3He flux through the Late Cretaceous

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doi: 10.1016/j.gca.2012.01.015
Author(s): Farley, K. A.; Montanari, A.; Coccioni, R.
Author Affiliation(s): Primary:
California Technical Institute, Division Geological and Planetary Sciences, Pasadena, CA, United States
Osservatorio Geologico di Coldigioco, Italy
Universita di Urbino Carlo Bo, Italy
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, Vol.84, p.314-328. Publisher: Elsevier, New York, NY, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. Includes appendices. 75 refs.; illus., incl. sketch map
Summary: Late Cretaceous (100-73 Ma) pelagic limestones were measured for helium concentration and isotopic composition to characterize the interplanetary dust flux using 3He as a tracer. In the Bottaccione section near Gubbio, Italy, three intervals of elevated 3He concentration were detected: K1 in the Campanian stage at ∼79 Ma, K2 in the Santonian stage at ∼85 Ma, and K3 in the Turonian stage at ∼91 Ma. All three of these episodes are associated with high 3He/4He and 3He/non-carbonate ratios, consistent with their derivation from an enhanced extraterrestrial 3He flux rather than decreased carbonate sedimentation or dissolution. While K2 is modest in magnitude and duration and thus is of limited significance, K1 and K3 are each identified by a few myr interval with an ∼4-fold enhancement in mean 3He flux compared with pre-event levels. Samples from ODP Hole 762C in the Indian Ocean spanning both K2 and K3 (93-83 Ma) confirm the presence of a peak in the Turonian stage, suggesting that K3 is a global event. The K1 and K3 3He events are similar in most respects to the two peaks previously detected in the Cenozoic, suggesting a similar origin. These have been attributed to a major asteroid collision in the Late Miocene and to a shower of either comets or asteroids in the Late Eocene. Based on the age and temporal evolution of K1, we suggest that it most likely records the collision which produced the Baptistina asteroid family independently dated at ∼80 Ma. The K3 event is less easily explained. It is characterized by an unusually spiky and erratic temporal progression, suggesting an unusual abundance of very 3He rich particles not previously seen in the sedimentary 3He record. We suggest this episode arises either from a comet shower or from an asteroid shower possibly associated with dust-producing lunar impacts. Abstract Copyright (2012) Elsevier, B.V.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Asteroids; Biostratigraphy; Bottaccione Italy; Carbonate rocks; Cenozoic; Chemical composition; Comets; Cosmochemistry; Cretaceous; Europe; Exmouth Plateau; Foraminifera; Geochemistry; Gubbio Italy; He-3; Helium; Impacts; Indian Ocean; Invertebrata; Isotopes; Italy; Leg 122; Limestone; Marches Italy; Mesozoic; Microfossils; Miocene; Neogene; Noble gases; ODP Site 762; Ocean Drilling Program; Perugia Italy; Protista; Santonian; Sedimentary rocks; Senonian; Southern Europe; Stable isotopes; Tertiary; Turonian; Umbria Italy; Upper Cretaceous; Upper Miocene
Coordinates: N422000 N434000 E0131500 E0115000
S195315 S195314 E1121515 E1121514
Record ID: 2012061440
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands