PREDICTABILITY OF SILURIAN FOSSIL-KONSERVAT-LAGERSTATTEN IN NORTH-AMERICA

Fossil-Konservat-Lagerstatten from a limited time frame can be classif ied in a way that provides predictive value, demonstrating that it is possible to prospect for additional deposits of exceptionally preserve d fossils. Q-mode cluster analysis reveals that eight Silurian Lagerst atten in North America are divisible into two groups on the basis of b iotic components and sedimentary features: eurypterid-phyllocarid-domi nated (EP) biotas (Williamsville, Syracuse, Pointe-aux-Chenes, Kokomo, Waubakee) and dendroid-graptolite-characterized (DG) biotas (Brandon Bridge, Lecthaylus, Mississinewa). All fossil deposits are characteriz ed by fine-grained, laminated, carbonate sediment bearing evidence of anoxic depositional conditions. The EP biotas were deposited in hypers aline peritidal lagoons limited stratigraphically to Upper Silurian st rata surrounding the Michigan Basin; similar Lagerstatten may be predi cted for this type of setting in North America and elsewhere in strata of like age. DG biotas are taxonomically, ecologically, stratigraphic ally, and areally more diverse than EP biotas, and these Lagerstatten are less easily predicted.