Abstract The chemical signatures of the sedimentary rocks of the Bathurst Mining Camp of northern New Brunswick define a regionally consistent stratigraphy with the chemical variations reflecting the changes in provenance over time. The Cambro-Ordovician Miramichi Group metasedimentary rocks indicate a derivation from a continental source (relatively low concentrations of Cr, Ni, and V, with high Zr and Y contents). In contrast, those of the Middle Ordovician California Lake, Tetagouche, and Fournier Groups are predominantly the erosional products of obducted ultramafic rocks (relatively depleted in Nb, Ti, Y, and Zr, and enriched in Cr and Ni). However, a transitional sequence of felsic (remnant arc-derived) rocks occurs in the earliest stages of the California Lake and Tetagouche Groups (i.e., Vallée Lourdes Member of the Nepisiguit Falls Formation) prior to the establishment of the mafic provenance that typifies the majority of sedimentary rocks in these groups. Subtle chemical variations have been identified throughout the Miramichi, California Lake, and Tetagouche Groups, such as the higher Mn content of the Chain of Rocks Formation compared to the Knights Brook Formation and the higher nickel content of the Little River Formation compared to the Nepisiguit Falls and Flat Landing Brook Formations. These chemical characteristics have locally enabled the resolution of stratigraphy within allochthonous thrust panels that are devoid of petrographically distinguishable sedimentary rocks, volcanic rocks, and/or fossil locations. The changing sediment provenance closely reflects the tectonic evolution of the region. Most of the Miramichi Group sedimentary rocks are derived from the generally granodioritic Avalonian basement. However, the uppermost part of the Miramichi Group (the Patrick Brook Formation) and the earliest parts of the California Lake and Tetagouche Groups (the Charlotte Brook and Vallée Lourdes Members, respectively) are juvenile products of the eroding remnant arc. In contrast, the great majority of the California Lake and Tetagouche Groups, as well as the coeval to slightly younger Fournier Group, contain clastic sedimentary rocks derived from an ophiolitic source, with the sedimentary rocks becoming progressively more mafic as the obducted sequence is unroofed. The development of indistinguishable clastic sedimentary stratigraphies within several groups that were deposited on potentially widely separated crustal blocks within the Tetagouche-Exploits back-arc basin dictates that the sedimentary rocks were not locally derived. As such, the sedimentary stratigraphy is able to complement the volcanic stratigraphies that are unique to each block in resolving the tectonic evolution of the region. For example, the possible remnant-arc volcanic rocks of the Clearwater Stream Formation are built on the arc-derived Patrick Brook Formation. This indicates that the history of arc development and rifting is diachronous from one block to another.

Location The city of Bathurst is located on Chaleur Bay in Gloucester County, northeastern New Brunswick (Fig. 1). Ordovician rocksof the Tetagouche Group that can be examined near the city arewithin the Bathurst Quadrangle (NTS 21 p.12), whereas those of the Fournier and Elmtree groups are seen to the north in the Pointe Verte Quadrangle (NTS 21 p.13). All described sites in the area are public and readily accessible by car; shore sectionsare best visited at low tide. Stop 1 is located at the provincial picnic site at Tetagouche Falls on the road to South Tetagouche. It is reached by taking Exit 310 off the Bathurst bypass (New Brunswick 11) and proceeding 6 mi (10 km) west (Figs. 1 and 2). Stop 2 is located onthe Bathurst bypass 2.2 mi (3.5 km) north of Exit 310 (Figs. 1and 3). Stop 3 is located on New Brunswick 11 about 0.6 mi (1 km) north of the Elmtree River bridge (Fig. 1). Stop 4 islocated on New Brunswick 11 at Exit 333 overpass (Fig. 1). Stop 5 is reached by taking the access road (Rue de la Gare) to Pointe Verte at Exit 333 on New Brunswick 11; proceed 3 mi (5 km) east along access road; pull off to the right just past railwaycrossing (Green Point Station) and walk south to quarry (Figs. 1and 4). Stop 6 is reached from Rue Principal (New Brunswick 134); proceed 2.8 mi (4.5 km) north on New Brunswick 134from Rue de la Gare in Pointe