Fission-Track Ages of Tuff Layers Related to the Pliocene-Pleistocene Boundary on the Boso Peninsula, Japan

1990 ◽  
Vol 33 (1) ◽  
pp. 86-93 ◽  
Author(s):  
Masao Kasuya
Keyword(s):  
Fission Track ◽  
Middle Part ◽  
Late Cenozoic ◽  
Boso Peninsula ◽  
Normal Polarity ◽  
Fission Track Ages ◽  
Age Constraints

AbstractFission-track ages of zircon crystals from four tuff layers in the late Cenozoic sediment sequence of the Boso Peninsula,.Japan, are 1.6 ± 0.2 myr (the Kurotaki Formation), 5.5 ± 0.6 and 5.2 ± 0.5 myr (the uppermost part of the Amatsu Formation), and 11.5 ± 0.8 myr (the middle part of the Amatsu Formation). These ages provide numerical age constraints on magneto-biostratigraphy. The normal polarity interval in the lower part of the Kiwada Formation corresponds to the Olduvai polarity subzone. The boundary between the Pliocene and Pleistocene lies slightly above the Olduvai polarity subzone.

scholarly journals Birth and closure of the Kallipetra Basin: Late Cretaceous reworking of the Jurassic Pelagonian–Axios/Vardar contact (northern Greece)

Solid Earth ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 2463-2485
Author(s):  
Lydia R. Bailey ◽  
Filippo L. Schenker ◽  
Maria Giuditta Fellin ◽  
Miriam Cobianchi ◽  
Thierry Adatte ◽  
...  
Keyword(s):  
Fission Track ◽  
Geothermal Gradient ◽  
Middle Part ◽  
Normal Faults ◽  
Illite Crystallinity ◽  
Northern Greece ◽  
Basin Inversion ◽  
Zircon Fission Track ◽  
Fission Track Ages ◽  
Fault Scarps

Abstract. Some 20 Myr after the Late Jurassic to Early Cretaceous obduction and collision at the eastern margin of Adria, the eroded Pelagonia (Adria)–Axios/Vardar (oceanic complex) contact collapsed, forming the Kallipetra Basin, described around the Aliakmon River near Veroia (northern Greece). Clastic and carbonate marine sediments deposited from the early Cenomanian to the end of the Turonian, with abundant olistoliths and slope failures at the base due to active normal faults. The middle part of the series is characterized by red and green pelagic limestones, with a minimal contribution of terrigenous debris. Rudist mounds in the upper part of the basin started forming on the southwestern slope, and their growth competed with a flux of ophiolitic debris, documenting the new fault scarps affecting the Vardar oceanic complex (VOC). Eventually, the basin was closed by overthrusting of the VOC towards the northeast and was buried and heated up to ∼ 180 ∘C. A strong reverse geothermal gradient with temperatures increasing up-section to near 300 ∘C is recorded beneath the VOC by illite crystallinity and by the crystallization of chlorite during deformation. This syntectonic heat partially reset the zircon fission track ages bracketing the timing of closure just after the deposition of the ophiolitic debris in the Turonian. This study documents the reworking of the Pelagonian–Axios/Vardar contact, with Cenomanian extension and basin widening followed by Turonian compression and basin inversion. Thrusting occurred earlier than previously reported in the literature for the eastern Adria and shows a vergence toward the northeast, at odds with the regional southwest vergence of the whole margin but in accordance to some reports about 50 km north.

Fission-track ages of late Cenozoic distal tephra beds in the Yukon Territory and Alaska

1982 ◽  
Vol 19 (11) ◽  
pp. 2167-2178 ◽  
Author(s):  
Nancy D. Naeser ◽  
John A. Westgate ◽  
Owen L. Hughes ◽  
Troy L. Péwé
Keyword(s):  
Fission Track ◽  
Yukon Territory ◽  
Late Cenozoic ◽  
Geologic History ◽  
Detailed Characterization ◽  
Track Method ◽  
History Of ◽  
Characterization Studies ◽  
Fission Track Ages ◽  
Tephra Beds

Six distal tephra beds from the Yukon Territory and Alaska have been dated by the fission-track method. Zircon and glass ages were determined for the Fort Selkirk and Lost Chicken tephra beds, but only glass ages for the others.Assuming that no track fading has occurred in the glass, Old Crow and Dawson tephra beds are younger than 120 000 and 52 000 years BP, respectively. Mosquito Gulch tephra is 1.22 Ma old, Fort Selkirk tephra is about 1 Ma old, the Ester Ash Bed is 0.45 Ma old, and the best estimate of the age of Lost Chicken tephra is the range 1.7–2.6 Ma.It is evident from these results and from the known abundance of tephra beds within late Cenozoic deposits of the Yukon Territory and Alaska that application of the fission-track method to distal tephra, in conjunction with detailed characterization studies, offers great potential for elucidation of the late Cenozoic geologic history of Alaska and the Yukon Territory.

Magnetostratigraphy of the Late Cenozoic of the Boso Peninsula, Central Japan

1977 ◽  
Vol 7 (3) ◽  
pp. 294-301 ◽  
Author(s):  
Hisao Nakagawa ◽  
Nobuaki Niitsuma
Keyword(s):  
Deep Sea ◽  
Middle Part ◽  
Boso Peninsula ◽  
Deep Sea Sediments ◽  
First Occurrence ◽  
Normal Polarity ◽  
Globorotalia Truncatulinoides ◽  
Geomagnetic Polarity ◽  
Continuous Deposition

Marine Pliocene and Pleistocene beds of the Boso Peninsula are more than 3 km thick and contain abundant fauna and flora. Almost continuous deposition occurred at a high sedimentation rate from the early part of the last reversed geomagnetic polarity epoch to the middle part of the last normal polarity epoch. Several microbiostratigraphic marker horizons enable correlation with deep-sea sediments fully independent of magnetostratigraphic zonation. Globorotalia truncatulinoides first occurs below the normal polarity event BO-B-2, which is correlated with the Olduvai Event in deep-sea sediments, whereas the disappearance of discoasters and the first occurrence of Gephyrocapsa caribbeanica are recognized at the top of BO-B-2, and the first occurrence of Gephyrocapsa oceanica is recognized at the top of BO-B-1. Based on the correlation of the Boso section with Mediterranean stage stratotype sections, the transition from the Pliocene to Pleistocene is estimated to be in the lower part of the Kazusa Group.

The Mid-Atlantic Ridge Near 45 °N. XXI. Magnetic Results from Basalt Drill Cores from the Median Valley

1973 ◽  
Vol 10 (5) ◽  
pp. 679-696 ◽  
Author(s):  
James Ade-Hall ◽  
Fabrizio Aumento ◽  
Patrick J. C. Ryall ◽  
Robert E. Gerstein ◽  
John Brooke ◽  
...  
Keyword(s):  
North Atlantic ◽  
Side Effect ◽  
Fission Track ◽  
Pillow Basalt ◽  
General Lack ◽  
Normal Polarity ◽  
Mid Atlantic Ridge ◽  
Fission Track Ages ◽  
Drill Cores

Natural remanence inclinations and paleointensities have been obtained from six drill cores of oceanic tholeiite pillow basalt taken from within a 4 km by 3 km area of the median valley of the Mid-Atlantic Ridge near 45 °N. Only two of the remanence inclinations agree with the predicted value for the area of +64°. Two others are of normal polarity but at +37 °and +47 °are significantly shallower than the predicted inclination. The remaining two cores have reverse inclinations of −14 °and −47°. Bottom photographs suggest that at least the +37 °and −47 °drill cores were obtained from in situ material.The paleointensities are uniformly high, ranging from 0.63 Oe to 1.17 Oe.The combined remanence inclination and paleointensity results are consistent with the presence on the floor of the median valley of basalts erupted during the Laschamps event, a conclusion in line with the fission-track ages for the basalts.It is suggested that the general lack of agreement between measured and predicted remanence inclinations, a feature that may be widespread in North Atlantic submarine basalts, is a side effect of the tectonic process responsible for the transport of new crust from the floor of the Median Valley to the adjacent crestal mountains.

Downstream Changes of Alpine Zircon Fission-Track Ages in the Rhone and Rhine Rivers

2004 ◽  
Vol 74 (1) ◽  
pp. 82-94 ◽  
Author(s):  
M. Bernet ◽  
M. T. Brandon ◽  
J. I. Garver ◽  
B. Molitor
Keyword(s):  
Fission Track ◽  
Zircon Fission Track ◽  
Fission Track Ages
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