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Re: New-ish Papers



Liu, Y., Liu, Y., and Zhang, H. 2006. LA-ICPMS zircon U-Pb dating in the Jurassic Daohugou Beds and correlative strata in Ningcheng of Inner Mongolia. Acta Geologica Sinica (English Edition) 80(5):733-742.
ABSTRACT: LA-ICPMS Zircon U-Pb dating is applied to volcanic rocks overlying and underlying the Salamander-bearing bed in the Daohugou beds of Ningcheng in Inner Mongola and Reshuichang of Lingyuan and Mazhangzi of Jianping in western Liaoning. The results indicate that the youngest age of the rocks in Daohugou of Ningcheng is 158 Ma, and the oldest one is 164 Ma. Synthesized researches indicate that the salamander-bearing beds in Daohugou of Ningcheng, Reshuichang of Lingyuan and Mazhangzi of Jianping were developed in the same period. The Daohugou beds were formed in the geological age of 164-158 Ma of the middle-late Jurassic. Whilst, the Daohugou beds and its correlative strata should correspond to the Tiaojishan Formation (or Lanqi Formation) of the middle Jurassic in northern Hebei Province and western Liaoning Province, based on the disconformity between the Daohugou beds and its overlaying beds of the Tuchengzi Formation of Late Jurassic and the Jehol Beds of early Cretaceous, and the disconformity between the Daohugou Beds and its underlying Jiulongshan Formation, which is composed of conglomerate, sandstone, shale with coal and thin coal beds.

- How can it be 164 Ma old, when the underlying Jiulongshan Fm is only 159 Ma old?
- Why do they claim the Tuchengzi Fm is Late Jurassic? A radiometric date from its "upper part" is 140 Ma -- that's the Berriasian-Valanginian boundary, well within the Early Cretaceous.
- If the Tuchengzi Fm really overlies the Daohugou Beds, however, that is interesting.


[...] the (ascending order) Revueltian, Apachean, Wassonian and Dawan land-vertebrate faunachrons (LVF).

Cool. The first two or three are named after the southwest USA, and Dawa is in China... that's Pangea for us, I guess...


The last collisional events of the Uralian orogeny took place during the Triassic and Early Jurassic time.

Wow.

A revised Milankovitch cyclostratigraphy based on new core and field data constrains the duration of eastern North America basaltic flows to 610 ky after the Triassic-Jurassic palynological turnover event.

Oho!

Palynological data indicates correlation of the initial carbon isotopic excursion of Hesselbo et al. [...] at St. Audrie's Bay to the palynological turnover event and vertebrate extinction level in eastern North America, suggesting a revised magnetostratigraphic correlation and robust carbon isotopic tests of the Marzoli-Knight hypothesis.

Good!

We conclude that as yet there are no compelling data showing that any of the CAMP predated or was synchronous with the Triassic-Jurassic extinction event.

:-)

The putative tsunamite in Northern Ireland is succeeded by a desiccation-cracked hiatus which may correlate with a similar hiatus truncating the seismite at sites in southern England. The hiatus in southern England correlates closely with a d13C isotope excursion that has been traced from eastern Europe across to western North America and is associated with significant biotic changes.

As predicted.