Page 273 - Carbonate Facies in Geologic History

260 Reef Trends and Basin Deposits in Late Jurassic Facies

··
....
U Groinatone on .. hooh
": ••
Thick ,h.1f "mellon.

I * I Evaporit ... wilh aolt
~ R .. h
300 .. Thick.o ..
in meters

Fig. IX-2. MaIm (Upper Jurassic) paleogeography in the Middle East showing basins with
salt, geosynclinal areas, shelves with oolite and tidal flat deposits, and general thicknesses

Terrigenous Source Area

Throughout the Late Jurassic a source of clastics existed west and north of the
European mainland. This source supplied more sediment toward the end of Ju-
rassic time than earlier. The western basins of Europe were filled by fresh water
and lagoonal evaporite facies during Purbeck ian time. The North Sea and English
basin contain thin lake deposits and the Spanish-Portugese coastal basins hold
exceedingly thick sections of terrigenous sediment including coals. The fresh-
water terrigenous clastic facies migrated across Europe to the Swiss-French Jura
area which contains the southernmost exposures of silty ostracod and Chara-
bearing Purbeck ian facies at the top of the Jurassic.