Bedrock Nomenclature of New Brunswick
LIME-KILN BROOK FORMATION(Windsor Group) Early Carboniferous
Author: Ryan and Boehner, 1994.
Type Locality:
Lime-kiln Brook Quarry and contiguous outcrops along Lime-kiln Brook near Nappan, Cumberland County, Nova Scotia (NTS 21 H/16W). Ryan and Boehner (1994) designated the Dewar Hill Quarry near Pugwash (NTS 11E/13) and drillhole NSDME LMA88-1 at Lower Maccan (NTS 21H/16) as reference sections in Nova Scotia. There is no completely exposed section of the Lime-kiln Brook Formation in New Brunswick, however, the section of clastics and overlying carbonates exposed at Hopewell Cape about 1 km north of the mouth of Demoiselle Creek (NTS 21 H/15) is representative of the upper part of the formation in that area.
Lithology:
The formation is divided into three informal members in New Brunswick (St. Peter and Johnson, in preparation): 1) white to grey, massive to granular and locally marble-textured gypsum with selenite porphyroblasts; grey massive to marble-textured, micro-crystalline anhydrite; minor medium to dark grey, micritic to wackestone and grainstone; minor red-brown, very fine-grained sandstone and conglomerate; 2) red-brown and rare grey-green, polymictic conglomerate, very-fine to medium-grained, parallel- and ripple-laminated sandstone and minor siltstone and mudstone; 3) buff to light brown weathering, grey fine- to coarse-grained fossiliferous, siliciclastic and oolitic grainstone and calcareous sandstone, locally containing stromatolite heads; red-brown to greyish red and grey polymictic pebbly sandstone and conglomerate; red-brown to grey, locally calcareous, fine-grained to granular lithic sandstone; minor dark grey fossiliferous siliciclastic wackestone, massive petroliferous shelly biomicrite, grey sandy to pebbly limestone, stromatolitic limestone breccia, red calcareous mudstone breccia and dark grey to grey-green siltstone to mudstone. Ryan and Boehner (1994) described the formation in Nova Scotia as being comprised predominantly of non-marine redbeds with subordinate marine carbonates and evaporites. The latter comprises anhydrite, gypsum and salt, fossiliferous marine limestone and dolostone. The clastics include fine-grained red sandstone, mudstone and locally minor grit to fine pebble conglomerate. The formation can be divided into at least three, and probably up to eight or more, marine cycles separated by redbeds.
Thickness and Distribution:
The Lime-kiln Brook Formation is restricted to the Sackville and Cumberland subbasins in New Brunswick and Nova Scotia, although its subsurface distribution is not well known. In the Hillsborough area (NTS 21 H/15E), the formation is exposed south and west of Hopewell Cape and in a narrow fault wedge northwest of there along the Harvey-Hopewell Fault. Farther southwest along the Harvey-Hopewell Fault on the northwest side of Chemical Creek, several shallow boreholes have intersected gypsum of the Lime-kiln Brook Formation. It is also exposed near the mouth of Daniels Brook and has been intersected in boreholes on the flats south of Shepody. A faulted slice of the Lime-kiln Brook Formation occurs just northeast of Lockhart Lake (NTS 21 H/10). It is exposed on the west side of the Maringouin Peninsula (NTS 21H/15, H/10) and extends as an east-west-trending tract of sink holes across the Peninsula to Pecks Cove (NTS 21 H/16). A separate outcrop is found about 1.5 km northwest of Grande Anse (NTS 21H/16). The Lime-kiln Brook Formation has a fairly wide but narrow distribution in Nova Scotia occurring within the cores of most major anticlines within the Cumberland Subbasin (NTS 21 H/16, 11E/12 and 11E/13). Its thickness at the type section is estimated at 285 m (Ryan and Boehner, 1994). About 9 km west of there at Lower Maccan, the formation is more than double the type section thickness at 640 m. In New Brunswick at the Shell Upper Dorchester No. 1 well, the Lime-kiln Brook Formation calculated true thickness is 365 m (St. Peter and Johnson, in preparation).
Relations to Other Units:
The formation is gradationally overlain by coarse alluvial redbeds of the Hopewell Cape Formation of the Mabou Group at the south end of Hopewell Rocks. It is conformably underlain by evaporites of the Pugwash Mine Formation of the Windsor Group. Subsurface data indicates that the formation is not present everywhere and the Lime-kiln Brook Formation apparently gives way laterally to and interfingers with the Maringouin Formation.
Age Justification:
Spore assemblages indicate a middle Visean age (Utting, 1987; Dolby, 1996b).
History:
The name Lime-kiln Brook Formation was first applied by Ryan and Boehner (1994) for the mixed carbonates, clastics, and evaporites that lie above the Pugwash Mine Formation in the Cumberland Subbasin of Nova Scotia. They noted that the formation was very similar to and probably correlative with the Demoiselle Creek beds described in the Hopewell Cape area by McCutcheon (1981b). Rocks now included in the Lime-kiln Brook Formation were mapped by Flaherty (1933) and Gussow (1953) near the mouth of Shepody River at Harvey Bank prior to construction of the dam. They also mapped an isolated exposure of gypsum and limestone on the north bank of the river at Riverside-Albert. Gussow (1953) recorded a limestone outcrop about 2 km southwest of Riverside-Albert and just south of Highway 915, however, like at Harvey Bank, the outcrop is no longer visible. McCutcheon (1981b) informally referred to these rocks as the Demoiselle Creek beds and described pelmatozoan fragments, ostracods, a high-spired gastropod, and foraminifera from the upper part of the unit at Hopewell Cape. Gussow (1953, p. 1747) assigned these rocks to Subzone C of the Windsor Group, but based on miospore assemblages McCutcheon (1981b) determined that the rocks were no younger than subzone B. St. Peter and Johnson (2003; in prep) confirmed the presence of the Lime-kiln Brook Formation in New Brunswick and provided the most comprehensive description of these rocks. The upper contact of the Lime-kiln Brook Formation at Hopewell Cape is described in detail in a field trip guidebook prepared by St. Peter (2003).
References:
Dolby, 1996b; Flaherty, 1933; Gussow, 1953; McCutcheon, 1981b; Ryan and Boehner, 1994; St. Peter and Johnson, (in prep), 2003; Utting, 1987.
Photographs:
233_Windsor_LimeK_1.jpg - Late Carboniferous Lime-kiln Brook Formation light grey limestone in lower part of photo overlain by Hopewell Cape Formation red conglomerates and sandstones in upper right of photo
233_Windsor_LimeK_2.jpg - Late Carboniferous Lime-kiln Brook Formation, algal stromatolite in carbonate grainstone
233_Windsor_LimeK_3.jpg - Late Carboniferous Lime-kiln Brook Formation, detail of laminated algal stromatolite
233_Windsor_LimeK_4.jpg - Late Carboniferous Lime-kiln Brook Formation, lumpy algal oncolitic limestone