Fossil nummulite tests are hardly found as complete tests. In 2004 Beavington-Penney pointed out that their state of preservation gives precious taphonomic information, especially about their degree of transportation.He built a scale of taphonomic features (numbered 0 to 3) easy to apply to the observation on thin sections. In this scale, from here on referred to as Beavington Taphonomic Index (BTI) the 0 category is the only one allowing an in situ interpretation; categories 1 to 3 could be interpreted either as transportation or as wave reworking.The current debate on the interpretation of nummulite banks as autochthonous or allochthonous sedimentary bodies can take advantage of information about the taphonomic features, so an examination of thin sections from nummulite banks and from ―normal‖ nummulitic limestones has started.The BTI has been applied to thin sections made on samples from the Pederiva di Grancona nummulite bank (SBZ 17, lower Bartonian) and from the nummulitic limestones (in ―normal‖ facies) from the Mossano section (SBZ 18, upper Bartonian). Both localities are in the Berici Mts. (Northern Italy), less than 10 km from each other. The Pederiva bank has been previously interpreted as relatively deep environment on the basis of the foraminiferal assemblage, which contains among others flat nummulites (such as the large Nummulites lyelli B), assilinas, operculinas, and orthophragminids. On the other hand, the upper Bartonian part of the Mossano section has been considered as quite shallow middle-inner platform subjected to the wave action (―shoal‖ facies).The taphonomic observations support this interpretation, giving a mean BTI between 1 and 2 for both samples, but a lower value has been calculated for Pederiva than for Mossano. Therefore, it seems that this index has a good correlation with the intensity of wave energy on the bottom.If we consider the bank as allochthonous, the low value of BTI could mean that it gives little information about the lateral transportation of the tests. On the contrary, if we assume the bank is the product of autochthonous deposition, we can consider the BTI as a useful tool to estimate the relative intensity of wave energy and possibly the depth.
Taphonomic index and transportation in nummulite banks and in nummulitic limestones / Papazzoni, Cesare Andrea. - STAMPA. - -(2010), pp. 154-155. ((Intervento presentato al convegno FORAMS 2010 International Symposium on Foraminifera tenutosi a Bonn nel September 5-10, 2010.
|Data di pubblicazione:||2010|
|Autore/i:||Papazzoni, Cesare Andrea|
|Titolo:||Taphonomic index and transportation in nummulite banks and in nummulitic limestones.|
|Nome del convegno:||FORAMS 2010 International Symposium on Foraminifera|
|Luogo del convegno:||Bonn|
|Data del convegno:||September 5-10, 2010|
|Citazione:||Taphonomic index and transportation in nummulite banks and in nummulitic limestones / Papazzoni, Cesare Andrea. - STAMPA. - -(2010), pp. 154-155. ((Intervento presentato al convegno FORAMS 2010 International Symposium on Foraminifera tenutosi a Bonn nel September 5-10, 2010.|
|Tipologia||Abstract in Atti di Convegno|
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