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EARLY FAUNAS AND CORRELATIONS, LABRADOR GROUP, SOUTHERN LABRADOR—WESTERN NEWFOUNDLAND

Douglas Boyce1, Ian Knight1, Christian Skovsted2 and Uwe Balthasar3 1 - GSNL; 2 - Swedish Museum of Natural History; 3 – University of Plymouth, England.

Paleontological, lithological and mapping studies of mixed siliciclastic‒carbonate rocks of the Labrador Group have been ongoing, since 1976, by the GSNL. Recent systematic litho- and bio-stratigraphic studies with Drs. Skovsted and Balthasar focus on trilobite and small shelly (SSF), mostly in the Forteau Formation. At least 34 co-eval sections have been measured, and 434 fossiliferous samples have been collected; publication of trilobite and SSF systematics is in preparation.

Dyeran to Topazan biostratigraphy, southern Labrador and western Newfoundland.

Early Cambrian and early Middle Cambrian global and Laurentian series and stages (Hollingsworth, 2011). Distribution of the Trilobite Faunas Early Cambrian trilobite faunas occur throughout the Forteau Formation and in the lowest strata of the overlying Hawke Bay Formation. They divide into two broad faunas – , mostly occur in deep-water shale and mudrocks, and Corynexochida, are hosted in shallow-water limestone, including archeocyathid reefs.

The Devils Cove member, basal Forteau Formation - a regionally widespread pink Bonnia sp. nov. Boyce: latex replica of limestone - hosts Calodiscus lobatus (Hall, 1847), logani (Walcott, partial, highly ornamented, spinose 1910), and Labradoria misera (Billings, 1861a). Calodiscus lobatus and E. logani range cranidium, Route 432, Great Northern Zacanthopsis sp. A Boyce: latex replica of Peninsula (GNP); it also occurs in the Deer high in the formation regionally, but L. misera is restricted to the lower 20 m of the partial cranidium, Mackenzie Mill member, Arm limestone, Mackenzie Mill member, formation in Labrador (includes archeocyathid reefs). GMNP. GMNP.

Bonnia parvula (Billings, 1861a), B. senecta (Billings, 1861a), E. logani and transitans (Walcott, 1910) are the most common in the Forteau Formation. The first three generally characterize shallow-water limestone and the last deep-water shale. Other taxa include Bonnia sp. nov. Boyce, mohavensis (Crickmay in Hazzard and Crickmay, 1933), Fritzolenellus lapworthi (Peach and Horne, 1892), Olenellus clarki (Resser, 1928), Olenellus thompsoni (Hall, 1859), walcottana (Wanner, 1901), Zacanthopsis sp. A Boyce, and various unidentified ptychopariids. Many occur in GMNP; most are new to Newfoundland.

Bristolia mohavensis (Crickmay in Elliptocephala logani (Walcott, 1910): Hazzard and Crickmay, 1933): incomplete latex replica, incomplete cephalon, Route O I O I O I O I O I 59 00 58 00 57 00 56 00 52 00 Belle cephalic sclerite, Route 432, GNP; it also 432, GNP. This distinctly ornamented Isle BEC

LOCATION OF É occurs in the basal Grosse Pointe member, trilobite characterizes the middle of the

MAP AREA basins QU LABRADOR Taconian Hawke Bay Formation, Canada Bay and Bonnia – Olenellus Zone in northwestern allochthons Pistolet Bay THERN characterizes the Bristolia mohavensis Zone Canada. Proterozoic

NOR basement + T supracrustal (Latham Shale, Mojave Desert, California, PENINSULA cover Strait of Belle Isle GREA T U.S.A.) (see upper left figure) DH AUL S. LAB x F Hare Bay HUMBER ZONE

LAKE NEWFOUNDLAND Plum Pt. R432 O I The basal Hawke Bay Formation is host to Bonnia columbensis Resser, 1936, Bristolia mohavensis, 51 00 O I 51 00 MILE Mesonacis bonnensis (Resser and Howell, 1938), and M. fremonti (Walcott, 1910). MSM 0 50 100 150 km Port au BER Choix TEN Canada Bay Peninsula AINS SYMBOLS Hawkes Bay Thrustcontact...... Laurentian Correlation of the Trilobite Faunas TRF StructuralbaseofTaconian allochthon ...... Fault ...... Table Pt. The Dyeran trilobite faunas of the middle Labrador Group can be correlated widely around the margin of Basal Cambrian unconformity ...... Carboniferous unconformity ...... . Elliptocephala logani is characteristic of the middle third, and B. columbensis the uppermost part Drill hole...... x DH Y O I Forteau Formation Study Areas...... O I 50 00 THERN PENINSULA 50 00 of the Bonnia – Olenellus Zone of the Sekwi Formation, Mackenzie Mountains, northwest Canada. WHITE BA

NOR T LONG RANGE MOUNT Fritzolenellus lapworthi is known from the 'Fucoid Beds', An-t-Sron Formation, northwest Scotland, and the

GREA Bastion Formation, North-East Greenland. Olenellus transitans and O. thompsoni occur in the Parker Bonne Bay GM Formation, Vermont, and Wanneria walcottana in the Kinzers Formation, Pennsylvania.

B LEGEND a y o f CARBONIFEROUS I s la Sedimentary rocks nds - In the Great Basin (western USA), Bristolia mohavensis is the nominate of the Bristolia mohavensis O I O I 49 00 Granitic rocks 49 00 GRAND Corner -DEVONIAN Zone (see above figures) in the Latham Shale. Olenellus clarki ranges from the lower Arcuolenellus arcuatus Brook LAKE Sedimentary and volcanic rocks Port au Port CAMBRIAN-ORDOVICIAN Zone to possibly the lowermost Bolbolenellus euryparia Zone; M. fremonti ranges from the middle of the Peninsula ALLOCHTHON Ophiolite complexes Arcuolenellus arcuatus Zone to the top of the Nephrolenellus multinodus Zone. This suggests overall that Sedimentary rocks/mélange Stephenville THRUST STACKS the trilobite fauna of the basal Hawke Bay Formation is restricted to the upper third of the Bonnia – Olenellus Transported shelf rocks Zone. AUTOCHTHON

Shelf and foreland basin rocks

CAMBRIAN-PROTEROZOIC O I 0 25 50 O I 48 00 Internal Humber Zone 48 00 km metasedimentary rocks Global Correlation of the Trilobite Faunas PROTEROZOIC Crystalline basement Calodiscus lobatus indicates a correlation with the Serrodiscus bellimarginatus-Triangulaspis annio-

O I O I O I O I 59 00 58 00 57 00 56 00 Hebediscus attleborensis assemblage in Avalonia, West Gondwana, Taconic Laurentia, and Siberia, but it also occurs in younger Cambrian strata: e.g., the Pagetides assemblage in the Taconic region of New York Primary geological terranes of western Newfoundland State, the Protolenus Limestone of England, and the Cephalopyge notabilis Zone /upper Hupeolenus Zone showing the Forteau Formation study areas (arrows). GM - Gros Morne National Park. of Morocco.