Tirabuzon Formation age?

[Darwin and Wallace]

Hey all,

 

Does anyone know the approximate age of the Tirabuzon Formation (AKA Corkscrew Hill) from Santa Rosalia, Mexico? I've seen that it's Pliocene but haven't gotten it narrowed down to the millions of years within the Pliocene. Some sources say late Pliocene while others say early Pliocene, so its been a bit confusing.

[Fossildude19]

According to this paper, 

 

" Based upon the benthic Foraminifera, the Tirabuzón Formation is assigned to a late Miocene-middle Pliocene age."  Pg. 45 (57 of PDF)

Regards,

[Darwin and Wallace]

That's excellent Fossildude19. Thanks!

 

[piranha]

The base of the Tirabuzón Fm overlies the cinta colorada volcanic unit dated at: 6.76 ± 0.90 Ma.

 

text and figure from:

 

Holt, J.W., Holt, E.W., & Stock, J.M. (2000)

An age constraint on Gulf of California rifting from the Santa Rosalía basin, Baja California Sur, Mexico.

Geological Society of America Bulletin, 112(4):540-549    

PDF LINK

 

"We have been able to further delimit the age of the Boleo Formation by obtaining an ⁴⁰Ar/³⁹Ar age of 6.76 ± 0.90 Ma for an intercalated volcanic unit known as the cinta colorada, which is a coarse-grained, primarily andesitic cinder bed (<2 m thick) with iron oxide cement (Wilson, 1948; Wilson and Rocha, 1955). Unlike particular conglomerate or sandstone layers, the cinta colorada is a true time marker as it was deposited over the entire area in a single event. This unit therefore provides an opportunity to obtain a direct isotopic age for the Boleo Formation."

 

 

[Darwin and Wallace]

Interesting. So according to this info, which is somewhat contrary to the previous poster's info, the Tirabuzon starts at around 7-6 MYA approximately, practically right at the end of the Miocene. Any idea how young it is approximately (7MYA-?MYA)? Anyone know when the Infierno formation begins?

[Fossildude19]

11 minutes ago, Darwin and Wallace said:

Interesting. So according to this info, which is somewhat contrary to the previous poster's info, the Tirabuzon starts at around 7-6 MYA approximately, practically right at the end of the Miocene. Any idea how young it is approximately (7MYA-?MYA)? Anyone know when the Infierno formation begins?

 

1 hour ago, Fossildude19 said:

According to this paper, 

 

" Based upon the benthic Foraminifera, the Tirabuzón Formation is assigned to a late Miocene-middle Pliocene age."  Pg. 45 (57 of PDF)

Regards,

 

Not really contrary at all.  

 

 

[Darwin and Wallace]

Fossildude19, you're totally right. For some reason I had it in my head that it said "middle Miocene" despite what was plainly in front of me. Sorry about that.

[Fossildude19]

No worries.

Stratigraphy can be difficult. 

At least. ... for me.  

 

EDIT:  Apologies in advance. 

 

I've been told that Stratigraphy is a multi-layered discipline.

[piranha]

1 hour ago, Darwin and Wallace said:

...Anyone know when the Infierno formation begins?

 

 

Approximately 3.9 Ma.

 

overlay chart from:

 

Ogg, J.G., Ogg, G.M., & Gradstein, F.M. (2016)

A Concise Geologic Time Scale: 2016.

Elsevier Scientific Publishing, 234 pp.

 

 

 

[Darwin and Wallace]

Brilliant. Thanks to both of you!

[Boesse]

In an unpublished manuscript I've let fall by the wayside, we argue for a Zanclean (early Pliocene age) of the Tirabuzon Fm.

 

Just out of curiosity - what's your interest with the Tirabuzon?

[siteseer]

4 hours ago, Boesse said:

In an unpublished manuscript I've let fall by the wayside, we argue for a Zanclean (early Pliocene age) of the Tirabuzon Fm.

 

Just out of curiosity - what's your interest with the Tirabuzon?

 

 

Hi Bobby,

 

You probably already know about Applegate (1978) which gives a short history of the area (which you couldn't deduce from the article title) and but I note it here for anyone interested.  I have another article about it somewhere but it's more of a general tourist blurb.  Back then the unit was tentatively called the "Gloria" Formation.  The presence of Carcharodon carcharias suggests an age no older than Early Pliocene and it would be no younger than Late Pliocene because of rare finds of Carcharocles megalodon and Parotodus benedeni.  The article provides a list of the sharks including Sphyrna mokarran.  Whether Early or Late Pliocene, I believe this is the earliest occurrence of the species in the fossil record.

 

I would guess the interest is in the shark teeth which were commercially available on occasion from about the late 70's to the mid 90's.  Mexico got serious about discouraging the export of fossils by around 2000 so you see only a few teeth recirculate from old collections every once in a while now.  

 

Jess

 

 

Applegate, S.A.  1978.

Phyletic Studies; Part 1; Tiger Sharks.  Univ. Nal. Auton. Mexico. Inst. Geologia. Revista.  Vol. 2.  Num. 1: 55-64.