RE: paleonet storm shelly deposits

["Esperante, Raul \(LLU\)" <resperante@xxxxxxx>]

Additional information about the possible storm bed:

This a Middle Miocene marine deposit. 
Thickness varies between 10-20 cm, fine to medium sst, shells are mostly bivalves, and a preliminary study suggests that they might be monospecific. Most of them are same size. Valves are articulated and in horizontal to subhorizontal position. No evidence for a scoured base or cross-bedding. Slight gradded bedding toward finer sst on top. Shells accumulate in the bottom third of the bed. I walked the bed for ~250 m, and vertebrate (mainly cetacean) bones occur every few cm. Sometimes partially articulated skeletons are within the bed in association with the shelss, which nevertheless are not attached to the bone surface. Most whale bones are disarticulated. Both articualted and disarticulated bones show excellent preservation, with no marks of abrasion or long time exposure. Patches of barnacles occur sparsely within the layer, and they seem to be in life position. Layers inmediately above and below are of similar lithological characteristics, but no fossils. Another shell-rich layer occurs ~1m above, but with no bones.

Hope this information will help.

Raśl Esperante, PhD
Paleontologist
Geoscience Research Institute
Loma Linda, California 92350, USA
Tel. (909) 558 4548
FAX (909) 558 4314
email: resperante@llu.edu


-----Original Message-----
From: paleonet-owner@nhm.ac.uk [mailto:paleonet-owner@nhm.ac.uk] On Behalf Of Seth Finnegan
Sent: Thursday, January 05, 2006 11:35 AM
To: paleonet@nhm.ac.uk
Subject: Re: paleonet storm shelly deposits


Raul-

   Can you give some more information on the bed's geological context (i.e., is it unique in the formation,or part of a recognizable cycle? does it differ from the the underlying and overlying beds in any sedimentological aspects other than bioclastic concentration? Does it have evidence of a scoured base, graded bedding, or cross-bedding?  Are the shells and bones current-aligned?

A good place to start might be numerous papers on storm sedimentation in this volume:

Cyclic and Event Stratification (Ed. by G. Einsele & A. Seilacher), pp. 161-174. Springer Verlag, New York.

Another similar volume with the title "Cycles and Events in Stratigraphy" was published in 1991, and is also worth checking out.  The papers on the Triassic Musselkalk might be especially interesting as they discuss both vertebrate and invertebrate remains in storm beds, I believe.  They are both available at the UCR library, not far from you.

             Good luck,
                             -Seth


---- Original message ----
>Date: Thu, 5 Jan 2006 09:56:13 -0800
>From: "Esperante, Raul \(LLU\)" <resperante@llu.edu>
>Subject: paleonet storm shelly deposits  
>To: <paleonet@nhm.ac.uk>
>
>   Happy New Year to all paleonetters:
>    
>   I am requesting some guidance in regard to a
>   possible storm deposit with marine vert and invert
>   material. The deposit consists of a 20-cm thick
>   layer of sst with shells and abundant marine
>   vertebrates, including sharks, fish and cetaceans. A
>   Georef search hasn't provided references that I use
>   to compare with. Could someone provide me with some
>   references of studies done in possible sotrm beds
>   with vert and invert material? Or can give a hint on
>   what the layer I'm studying could be?
>    
>   Raśl Esperante, PhD
>   Paleontologist
>   Geoscience Research Institute
>   Loma Linda, California 92350, USA
>   Tel. (909) 558 4548
>   FAX (909) 558 4314
>   email: resperante@llu.edu
>    
Seth Finnegan
Dept. of Earth Sciences -036
University of California
Riverside, CA 92521
Phone:(951)452-2759
Fax:  (951)787-4324