Dear colleagues
The attached file consists of an image which taken from paleogene phosphatic limestones of Pabdeh Formation in Lar mountains (south west of Iran). Nominated layer belongs to middle part of this Formation and based on planktonic foraminiferal studies (Daneshian et al., 2015) estimated Lutetian-Bartonian stage. Field and petrographic studies denote that there are some sedimentary structures such as: Hummocky cross stratification, cross lamination, ripple marks and amalgamation which can be categorized as tempestites. Please, if you find any mistakes in my opinion, could you please correct them?
Hello,
The two pictures with laminae make me think about the La Luna Fm. of Venezuela (Late Cretaceous) and suggest pelagic deposition. I would not speak about tempestites but about calm depositional conditions with recurrent periods of planktic-foram accumulations.
Hi again,
see also :
High-resolution stratigraphy and facies architecture of the Upper Cretaceous (Cenomanian–Turonian) Eagle Ford Group, Central Texas
ARTICLE in AAPG BULLETIN 100(03):379-403 · MARCH 2016 with 9 READS
Impact Factor: 2.61 · DOI: 10.1306/12071514187
1st Michael D. Fairbanks, 2nd Stephen C. Ruppel, 3rd Harry Rowe
You may find it on Research gate through the page of Harry Rowe.
Have a nice week,
NT
Dear Armin Salsani,
If these deposits are truly a tempestite (talking about a complete, idealized tempestite of intermediate distance from the coast line), they don´t look as typical ones.
The image of the HCS is not clear, and to me looks just a (subhorizontal) parallel lamination.
The existence of fine material could be the record of redeposited shelf mud. This along with the ripple cross-lamination would be a support for a tempestite.
Nevertheless, you should need a clear evidence of graded layer with basal lag deposit, and a erosive base with sole marks. Also, it would be useful to recognize intensely bioturbated shelf deposits below these succession.
If you think that this sucession would correspond to "distal" tempestite, the presence of parallel lamination would be ok, since HCS becomes less distinct, and can be replaced by the former structure.
Alternatively, if these facies from the pictures, correspond to distal sites, you can think just in underflows deposits. They present parallel lamination, and also ripples upward de succession,
Cheers,
Marcelo
Dear Armin,
The HCS image is not clear, it is necessary in this case seek the lateral variation if you find a better section with a term C with well clear HCS. It should also seek other terms of tempestite sequence. In the absence of term HCS, you must beware it could be a turbidite ! The main characteristic that distinguishes between a tempestite and turbidite is the term C with a HCS for tempestite and convoluted for turbidite.
The ripple mark image, rather shows a lamination structures (light bed / dark bed) !!
Best Regards.
M. Berkhli
HI,
Please, read this article :
Pomar L., Morsilli, M, Hallock, P. et Bádenas, B. 2012. Internal waves, an underexplored source of turbulence events in the sedimentary record. Earth-Science Reviews, 111, pp. 56-81.
It can gives you more ideas.
Good luck
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