Illtyd Formation : Wikipedia, the free encyclopedia

Illtyd Formation

Illtyd Formation
Stratigraphic range: Cambrian
Type	Formation
Underlies	Slats Creek Fm
Location
Region	Yukon
Country	Canada

The Illtyd Formation is an up to 1000-m thick geologic formation in Yukon. It preserves fossils dating back to the Dyerian subdivision of the Cambrian period, which spans the Stage 3 / Stage 4 boundary; it's considered to belong to the mid-upper Bonnia-Olenellus trilobite Zone. Top of the unit corresponds, more or less, to the top of Stage 4.^[1]^[2] These fossils include Lower Cambrian trilobites'.^[3]

The type section is in the Wernecke Mtns; it corps out also in and to the S/SW of the Rochardson Moutnars. It possibly corresponds to the Sekwi Fm in the Macxkenzie mtns.^[1]

Lowermost of the Palaeozoic strata west of the Richardson Mountains, angular unconformity at base, overlying various Precambrian strata. Silty limestones and massive dolomites. In places rhythmically bedded. Colour: Tan, brownish grey muds; sandier layers orange. Upper layers include oolites and oncolites. Trace fossils include burrows and 'worm trails'. In some places unit is massively faulted and altered / weathered, approaching marble grade metamorphism near faults.^[1]

References

^ ^a ^b ^c Morrow, D. W. (1999). Lower Paleozoic stratigraphy of northern Yukon Territory and northwestern District of Mackenzie. Bulletin 538. Geological Survey of Canada. ISBN 0-660-17808-7.
^ Foster, John R. (2011). "sp.(Trilobita; Corynexochida) from the Chambless Limestone (Lower Cambrian) of the Marble Mountains, California: First Dorypygidae in a cratonic region of the southern Cordillera". PaleoBios. 30 (2).
^ Fritz, W. H. (1991). Lower Cambrian trilobites from the Illtyd Formation, Wernecke Mountains, Yukon Territory. Bulletin. Geological Survey of Canada. ISBN 0-660-13836-0. ISSN 0068-7626.