Influence of uranium post-incorporation on the fossil mollusk shell age rejuvenation

Application to the study of the marine level variation in the past

A. Choukri1*, E. Jahjouh1, S. Semghouli1, O.-K. Hakam1, J.-L. Reyss2

1 L.F.R.E, Université Ibn Tofail, Faculté des Sciences

Département de physique, B. P. 133, Kénitra, Morocco

2 L.S.C.E, Avenue de la Terrasse

91198, Gif sur Yvette Cedex, France

* Corresponding author. E-mail : choukrimajid@yahoo.com

Received 20 October 2000

Abstract

We discuss two models based on episodic and continual uranium migration into mollusk shells after death and give a relationship between the apparent and real ages. For the episodic model, we discuss this relationship according to the uranium post-incorporation rate, the initial 234U/238U activity ratio and the time of incorporation. We test both models on some of mollusk shells taken from four fossil marine shorelines on the Atlantic coast of the Moroccan High Atlas assumed formed during the last interglacial stage about 122 000 years ago. We try to draw a general conclusion concerning the unreliability of mollusk shell samples for uranium series dating.

Keywords: Uranium series dating; Open system; Continual uranium post-incorporation model into fossil mollusk shells; Episodic uranium post-incorporation model into fossil mollusk shells.

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