Sedimentology of the Minette oolitic ironstones of Luxembourg and Lorraine: a Jurassic subtidal sandwave complex

Abstract

The oolitic ironstones of the Minette were deposited during Toarcian/Aalenian times in a nearshore environment of the Paris Basin. The sedimentary sequence comprises up to 13 coarsening upward depositional cycles. The development of the cycles and different facies types are described. The iron ooids accumulated in a subtidal environment under the effects of tidal currents. Sand waves, which form an important part of the Minette sediments, were deposited under both time‐velocity symmetrical and time‐velocity asymmetrical tides. From the study of their internal structures the time‐velocity patterns of the currents, current speeds (up to 0±9m s−1) and net transport rates have been estimated (29 g m−1 s−1 in the case of large‐scale sand waves controlled by time‐velocity symmetrical tides). Sand wave heights and calculated near‐bed current speeds suggest a mesotidal regime. Sedimentary facies include large‐scale and waves, subtidal shoals with channels and an offshore muddy shelf. Conclusions as to bathymetry are drawn from ichnofaunal associations and from the study of wave ripple marks. Finally a depositional model of the Minette iron formation is proposed which may be applicable to other oolitic ironstones.

The Role of Microbial Activity In the Generation of Lower Cretaceous Mixed FE-Oxide-phosphate Ooids from the Provencal Domain, French Maritime Alps

“…Episodic highenergy events would be responsible for winnowing and ooid concentration to give rise to grainstones, commonly as bedforms internally showing cross-lamination (Teyssen 1984;Donaldson et al 1999). Environmental conditions should be mainly oxidizing, although the presence of ferrous-iron-bearing chamosite suggests development under partially reducing conditions.…”

“…Some layers may also be formed by clay or carbonate minerals. Fe-rich layers may be limonitic or be composed of berthierine and chamosite (Teyssen 1984;Burkhalter 1995;Sturesson et al 2000;Karakus et al 2001).…”

Metallogenesis of cratonic oolitic ironstone deposits in the Bled el Mass, Azzel Matti, Ahnet and Mouydir basins, Central Sahara, Algeria

“…A tidal control of oolitic sedimentation has previously been suggested by TEYSSEN (1984) for the Jurassic minette of Luxembourg and Lorraine.…”

Lower Ordovician ooids from northern Öland, Sweden

“…Siehl & Thein 1978;Ranger 1979;Nahon et al 1980;Swirydczuk et al 1980;Bhattacharyya & Kakimot0 1982;Maynard 1983;Teyssen 1984). Some of the suggested models are not applicable to the material from Oland, but two will be discussed:…”