The stratigraphy of the Gault and Upper Greensand of the Weald

Support for a Vraconnian Stage between the Albian sensu stricto and the Cenomanian (Cretaceous System)

“…Although the species was described as far back as 1973 by SCHOLZ at Briac near Saint-Martin-en-Vercors (Drôme), then by DELANOY & LATIL (1988) at Pont-de-Peille (Alpes maritimes) -two outcrops in southeastern France (Fig. 2) Other ammonites too are typical of the M. (BREISTROFFER, 1940a;DESTOMBES, 1958;AMÉDRO, 1992), Belgium (MARLIÈRE, 1942(MARLIÈRE, , 1965, U.K. (SPATH, 1943;OWEN, 1976), Switzerland (RENZ, 1968, Hungary (SCHOLZ, 1979), Crimea (MARCINOWSKI & NAIDIN, 1976), Ukraine, Turkmenistan (ATABEKIAN, 1985(ATABEKIAN, , 1992, Sardinia (WIEDMANN & DIENI, 1968), Madagascar (BOULE et alii, 1906, Texas (CLARK, 1965), ... : Vertical distribution of some significant Vraconnian ammonites in the reference sections of northwestern Europe and, just below the zonation in current use, the proposal of an alternative zonation based on the evolution of the Stoliczkaiinae. Data for the several sections are taken from the following works: La Vraconne (RENZ & LUTERBACHER, 1965;RENZ & JUNG, 1978), Cambridge (EDMONDS & DINHAM, 1965), Salazac (LATIL, 1994b), La FaugeBriac (BREISTROFFER, 1936SCHOLZ, 1973), Pont-de-Peille (DELANOY & LATIL, 1988, Risou (GALE et alii, 1996).…”

“…The OWEN, 1976OWEN, , 1996a In fact, the meaning that RENEVIER assigns the Vraconnian is more restrictive, as indicated by the remarks concerning the paleontologic content of the future stage given a few pages previously (p. 474 and p. 475): "I add, finally, that at Ste Croix and at Cheville, the fauna of the upper Gault becomes remarkably similar to that of the Upper Greensand, and, if I am not mistaken, it contains, along with many other species of that level, the famous Pecten asper, in France considered characteristic of the Lower Cenomanian [...]. In Switzerland, that fauna is particularly rich in cephalopods, gastropods and bivalves [...], nowhere else has it been studied as thoroughly as in the rich deposit of the La Vraconne, made classic by the excellent monograph of PICTET & CAMPICHE, that is why I give this assemblage of fossils the name Faune vraconnienne".…”

“…Present day knowledge of Vraconnian ammonite faunas is the result of a multitude of studies, mostly in Europe. The most significant of them are those of SPATH (1923SPATH ( -1943, BREISTROFFER (1936BREISTROFFER ( , 1940aBREISTROFFER ( , 1940bBREISTROFFER ( , 1946BREISTROFFER ( , 1947, RENZ & LUTERBACHER (1965), RENZ (1968), KENNEDY (1970), SCHOLZ (1973SCHOLZ ( , 1979, OWEN (1976OWEN ( , 1984OWEN ( , 1996aOWEN ( , 1999, COOPER & KENNEDY (1977, 1979, 1987, DELANOY & LATIL (1988), AMÉDRO (1992), WRIGHT & KENNEDY (1994), KENNEDY & DELAMETTE (1994), LATIL (1994b), GALE et alii (1996), DELAMETTE et alii (1997) and KENNEDY et alii (1998). The geographic locations of the strata in the Swiss Jura and in southeastern France cited in the following text are indicated in Figure 2. …”

“…As a consequence the Vraconnian-Cenomanian boundary is shifted slightly lower with respect to the previous divisions based on ammonites. (BREISTROFFER, 1940a(BREISTROFFER, , 1947AMÉDRO, 1985;GALE et alii, 1996;AMÉDRO & ROBASZYNSKI, 1998), U.K. (SPATH, 1943;KENNEDY, 1970;OWEN, 1976OWEN, , 1996b, Germany (OWEN, 1989), Switzerland (RENZ, 1968), Rumania (CHIRIAC, 1981), Hungary (SCHOLZ, 1979), Turkmenistan (ATA- BEKIAN, 1985BEKIAN, , 1992, Crimea (MARCINOWSKI & NAIDIN, 1976), Sardinia (WIEDMANN & DIENI, 1968), Tunisia (PERVINQUIÈRE, 1907), Angola (SPATH, 1922;COLLIGNON, 1978a;COOPER & KENNEDY, 1979), Nigeria (REYMENT, 1955), South Africa (SPATH, 1921), India (STOLICZKA, 1865), Madagascar , Texas (YOUNG, 1957), California (MURPHY & RODDA, 1996), ...…”

“…It is certain that it was in the Anglo-Paris basin during the XIX th century that the major principles of stratigraphy were developed and where d'ORBIGNY (1842-1847) created the major stages of the middle Cretaceous, the Cenomanian and Turonian. Field work supplemented by well data in the central part of the basin in both France (LAUVERJAT, 1967(LAUVERJAT, , 1974JUIGNET, 1974;MÉDIONI et alii, 1980) and Great Britain (JUKES-BROWNE & HILL, 1900;SHERLOCK, 1960;GALLOIS & EDMUNDS, 1965;OWEN, 1976;GALLOIS & MORTER, 1982) make possible a map showing the distribution of Vraconnian facies. Figure 13 shows three main facies:…”