Re: New-ish Papers

[David Marjanovic <david.marjanovic@gmx.at>]

> 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.