Joggins Formation Research Articles

Role of evaporite withdrawal in the preservation of a unique coal-bearing succession: Pennsylvanian Joggins Formation, Nova Scotia

The Pennsylvanian Joggins Formation, in the Cumberland Group of Nova Scotia, is widely regarded as the world's best exposure of coal-bearing Carboniferous strata. This 1.5-km-thick coal-bearing unit is famous for upright fossil lycopsid trees, and is preferentially preserved in the Athol syncline in the western Cumberland basin. New seismic profiles show that the Athol syncline is atop a salt weld and that the Joggins Formation thins on the flanks of adjacent evaporite-cored anticlines. These observations indicate that during deposition of the Joggins Formation, at least 1 km of syndepositional subsidence was facilitated by flow of underlying salt into the adjacent anticlines. In contrast, halo-kinesis was mainly active during the Mississippian in the eastern Cumberland basin (Tatamagouche syncline); minibasins were filled by Mabou Group sediments, whereas the Cumberland Group is thin and lacks significant coals. This basinwide comparison shows that much of the subsidence responsible for the preservation of the coal-bearing Joggins Formation was the result of salt withdrawal at depth.

Vegetation‐induced sedimentary structures from fossil forests in the Pennsylvanian Joggins Formation, Nova Scotia

AbstractVegetation‐induced sedimentary structures (VISS) are primary structures formed by the interaction of detrital sediment within situplants. VISS provide physical evidence of vegetation's fundamental role in mediating sediment accumulation and erosion in clastic depositional systems. Despite the abundance of modern VISS, descriptions from the ancient record are surprisingly rare. Analysis of fossil forests in floodplain strata of the Pennsylvanian Joggins Formation has identified seven types of VISS. Five hydrodynamic types comprise simple forms developed around a single plant (centroclinal cross‐strata, scratch circles, upturned beds) and complex forms where structures have amalgamated between several plants (coalesced scour fills, scour‐and‐mound beds). Two types (mudstone‐filled hollows, downturned beds) form by the decay of an entombed plant and represent infilling of an empty hollow and/or soft‐sediment deformation. Hydrodynamic types are present in both dryland and wetland settings, whereas decay‐related types occur only in dryland settings where the water table was perennially or periodically low. VISS represent significant accumulations of sediment and are present in a high proportion of Joggins Formation strata. The paucity of descriptions from the ancient record suggests that these structures have been overlooked or misinterpreted as strictly hydrodynamic. Recognition of VISS in early to middle Palaeozoic strata may provide an important insight into the distribution of early land plants in oxidizing environments where organic material was not preserved.

On the discovery of a unique terrestrial faunal assemblage in the classic Pennsylvanian section at Joggins, Nova Scotia

A rich fossil assemblage discovered from the classic Pennsylvanian locality of Joggins, Nova Scotia, is here described for the first time. The 2 m-thick Hebert sandstone, within the lower Joggins Formation of early Langsettian age, is the most productive stratum at Joggins of terrestrial tetrapods and the pulmonate gastropod Dendropupa vetusta exclusive of the historic fossil forest locality of Dawson and Lyell, and the most productive Pennsylvanian locality in the world of the large unionoid bivalve genus Archanodon. Although the land snail–archanodontid bivalve–tetrapod assemblage of the Hebert Sandstone comprises a unique late Paleozoic terrestrial dryland biota, individual taxa were not endemic to drylands alone.

Response of Late Carboniferous tropical vegetation to transgressive–regressive rhythms at Joggins, Nova Scotia

Fossil plant assemblages are described in their sequence stratigraphic context from the Upper Carboniferous (Langsettian) Joggins Formation of Nova Scotia to elucidate ecosystem response to transgressive–regressive rhythms. Results show that rising base level resulted in retrograding submerged coastal mires co-dominated by Lepidodendron and Lepidophloios , which were replaced by short-lived Paralycopodites communities immediately following mire drowning. Extensive brackish bays existed during early highstand, distally fringed by gymnospermous and putative progymnospermous coastal and/or upland vegetation. Late highstand bay filling generated prograding distributary wetlands dominated by flood-disturbed lycopsid–pteridosperm–sphenopsid communities, and locally by cordaite mangroves. As base level fell, well-drained alluvial plains were dominated by fire-prone cordaite and/or Sigillaria communities, which persisted until the next phase of base-level rise. This rhythmic ecosystem succession repeatedly occurred on a c . 50–200 ka time scale, and was probably driven by glacial–interglacial climate rhythms.

Architecture of coastal and alluvial deposits in an extensional basin: the Carboniferous Joggins Formation of eastern Canada

Abstract The Joggins Formation was deposited in the Cumberland Basin, which experienced rapid mid‐Carboniferous subsidence on bounding faults. A 600 m measured section of coastal and alluvial plain strata comprises cycles tens to hundreds of metres thick. The cycles commence with coal and fossiliferous limestone/siltstone intervals, interpreted as widespread flooding events. These intervals are overlain by coarsening‐upward successions capped by planar‐based sandstone mounds, up to 100 m in width that represent the progradation of small, river‐generated delta lobes into a standing body of open water developed during transgression. The overlying strata contain sand‐rich heterolithic packages, 1–8 m thick, that are associated with channel bodies 2–3 m thick and 10–50 m wide. Drifted plant debris, Calamites groves and erect lycopsid trees are preserved within these predominantly green‐grey heterolithic sediments, which were deposited on a coastal wetland or deltaic plain traversed by channel systems. The cycles conclude with red siltstones, containing calcareous nodules, that are interbedded with thin sandstones and associated with both single‐storey channel bodies (1–1·5 m thick and 2–3 m wide) and larger, multistorey channels (3–6 m thick) with incised margins. Numerous channel bodies at the same level suggest that multiple‐channel, anastomosed river systems were developed on a well‐drained floodplain. Many minor flooding surfaces divide the strata into parasequences with dominantly progradational and aggradational stacking patterns. Multistorey channel bodies are relatively thin, fine grained and modestly incised, and palaeosols are immature and cumulative. The abundance and prominence of flooding surfaces suggests that base‐level rise was enhanced, whereas the lack of evidence for abrupt basinward stepping of facies belts, coupled with the absence of strong fluvial incision and mature palaeosols, suggests that base‐level fall was suppressed. These architectural features are considered to reflect a tectonic architectural signature, in accordance with the high‐subsidence basinal setting. Evidence for restricted marine influence and variation in floral assemblages suggests modulation by eustatic and climatic effects, although their relative importance is uncertain.

Late Carboniferous Tropical Dryland Vegetation in an Alluvial-plain Setting, Joggins, Nova Scotia, Canada

Abstract The composition and ecology of Late Carboniferous tropical, dryland plant communities are described for the first time. The study focuses on a 700-m-thick succession through the Langsettian Joggins Formation. Red bed units (5–110 m thick) bearing isolated pedogenic carbonate nodules occur at fourteen intervals and are interpreted as originating in a seasonally dry, well-drained, alluvial-plain setting characterized, in places, by an anastomosing fluvial geometry. A quantitative quadrat analysis of red bed floral assemblages preserved as compressions, impressions, calcareous permineralizations, and charcoal was undertaken. Cordaites, represented by woody trunks, branches, pith casts, leaves, and seeds, comprise 74% of the red bed floral thanatomass, together with minor pteridosperms and sphenopsids, and rare sigillarian lycopsids. Taphonomic data demonstrate that while fire-prone cordaite-pteridosperm vegetation dominated nearly all seasonally dry floodplain niches, hydrophilic lycopsids and sphen...

Fluvial Sedimentology of the Joggins Formation (Pennsylvanian), Cumberland Basin, Nova Scotia

Fluvial Sedimentology of the Joggins Formation (Pennsylvanian), Cumberland Basin, Nova Scotia

Metalliferous coals of the Westphalian A Joggins Formation, Cumberland Basin, Nova Scotia, Canada: petrology, geochemistry, and palynology

Five coals of Westphalian A (early Middle Pennsylvanian) age were sampled from the Joggins Formation section exposed along Chignecto Bay at Joggins, Nova Scotia. Coal beds along the bay were mined beginning in the early 17th century, yet there have been few detailed published investigation of the coal beds of this classic section. The lowermost coal, the Upper Coal 28 (Upper Fundy), is a high-vitrinite coal with a spore assemblage dominated by arboreous lycopsid spores with tree ferns subdominant. The upper portions of the coal bed have the highest ratio of well-preserved to poorly-preserved telinite of any of the coals investigated. Coal 19 (“clam coal”) has 88% total vitrinite but, unlike the Fundy coal bed, the telinite has a poor preservation ratio and half the total vitrinite population comprises gelocollinite and vitrodetrinite. The latter coal bed is directly overlain by a basin-wide limestone bed. The Lower Kimberly coal shows good preservation of vitrinite with relatively abundant telinite among the total vitrinite. The Middle Kimberly coal, which underlies the tetrapod-bearing lycopsid trees found by Lyell and Dawson in 1852, exhibits an upward decrease in arboreous lycopod spores and an upward increase in the tree fern spore Punctatisporites minutus. Telinite preservation increases upwards in the Middle Kimberly but overall is well below the preservation ratio of the Upper Fundy coal bed. The coals all have high sulfur contents, yielding up to 13.7% total sulfur for the lower lithotype of the Upper Fundy coal bed. The Kimberly coals are not only high in total and pyritic sulfur, but also have high concentrations of chalcophile elements. Zinc, ranging up to 15,000 ppm (ash basis), is present as sphalerite in fusain lumens. Arsenic and lead each exceed 6000 ppm (ash basis) in separate lithotypes of the Kimberly coals. Together these data are consistent with elevated pH in planar mires. The source of the elemental enrichment in this presumed continental section is enigmatic.

Petrology, Geochemistry, and Palynology of Joggins Formation (Westphalian A) Coals, Cumberland Basin, Nova Scotia: ABSTRACT

Five Westphalian A coals were collected from the Joggins Formation section exposed along Chignecto Bay at Joggins, Nova Scotia. Several of the coal beds along the bay were mined beginning in the early 17th century. There has been little detailed investigation of the coal beds of this classic section. The lowermost coal, the Upper Coal 29 (Fundy), is a high-vitrinite coal with a spore assemblage dominated by arboreous lycopod spores with tree ferns subdominant. The upper portions of the coal bed have the highest ratio of well-preserved to poorly-preserved telinite of any of the coals investigated. Coal 19 (Forty Brine) has 88% total vitrinite but, unlike the Fundy coal bed, the telinite has a poor preservation ratio and half of the total vitrinite population comprises gelocollinite and vitrodetrinite. The latter coal bed is directly overlain by a basin-wide limestone bed. The Lower Kimberly (Coal 15) shows good preservation of vitrinite with relatively abundant telinite among the total vitrinite. The Upper Kimberly, which underlies the tetrapod-bearing lycopsid trees found by Lyell and Dawson in 1852, exhibits an upward decrease in arboreous lycopod spores and an increase in the tree fern spore Punctatisporites minutus. The megaspore record is similarly dominated by Lagenicularugosamore » paralycopodites and tree fern spores. Telinite preservation increases upwards in the Upper Kimberly but overall is well below the preservation ratio of the Fundy coal bed. The coals are all high sulfur, up to 13.7% total sulfur for the lower lithotype of the Fundy coal bed. The Kimberly coals are not only high in total and pyritic sulfur, but also have high concentrations of chalcophile elements.« less

Continental hydrology and climatology of the Carboniferous Joggins Formation (lower Cumberland Group) at Joggins, Nova Scotia: evidence from the geochemistry of bivalves

The Pennsylvanian section at Joggins contains bivalves, possibly representing several species of Naiadites, in great abundance within certain beds of the Joggins Formation (Westphalian A). Shells are chalky-white and in most specimens the internal microstructure is preserved as nacreous tablets which are always aragonite. This site represents the oldest-known occurrence of Paleozoic non-marine biogenic aragonite. Geochemically the bivalves are distinct from coeval tropical marine, based on stable and radiogenic isotopes, and terrestrial counterparts based on their trace element contents. The Sr, Mg, Na, Mn and Fe contents are strongly habitat controlled by ambient environmental conditions and suggest a near-shore continental lacustrine-paludal environment. The high enrichment factors for Mn and Fe suggest slightly dysaerobic water conditions during shell secretion. The δ 13C (+2.11 to +2.24%, PDB) and δ 18O (−5.83 to −5.72%, PDB) values, after mineralogy correction, for the Joggins bivalves are dissimilar to those of shallow-water, paleoequatorial brachiopods, but suggests that Naiadites also preferred warm, shallow waters. Furthermore, the postulated composition and temperature for annual precipitation of −5.5 to −2.3%, δ 18O (SMOW) and 18–24°C, respectively, support the equatorial position of this locality during the Pennsylvanian. Water reaching the Joggins locality was probably of a rheotrophic nature derived from rain in Caledonia Highlands. This “local” origin of the meteoric water is further supported by its Sr isotopic composition. In addition, the 87Sr/ 86Sr ratios of the Joggins bivalves (>0.7093) are significantly different from those of coeval brachiopods and mollusks (<0.7085). This isotopic invariance between marine and non-marine invertebrates provides incontrovertible evidence and support for the non-marine paleoecology of Naiadites and thus the enclosing sediments of the upper Joggins Formation.

Magnetic polarity stratigraphy and carboniferous paleopole positions from the Joggins Section, Cumberland Structural Basin, Nova Scotia

One hundred seventy‐seven samples were taken in stratigraphic sequence in redbeds from approximately 2100 m of Namurian‐Westphalian strata from the Shepody, Enragé, Boss Point, and lower Joggins formations between Minudie and Joggins, Nova Scotia, for the purpose of constructing a magnetic polarity stratigraphy. In addition, five samples from each of four sites were taken from north dipping strata of the Cumberland Group for the purpose of conducting a fold test for the Joggins Formation. This yields a total coverage of 412 samples from approximately 2400 m of south dipping strata in the composite section when combined with previous results from the Maringouin Peninsula (DiVenere and Opdyke, 1990) and 88 samples from north‐dipping strata collected for the purpose of conducting fold tests. Two components of magnetization are identified in these sediments: a prefolding component, termed C, and a synfolding component, termed B. The present results extend the mid‐Carboniferous magnetic polarity stratigraphy to include eight normal and eight reversed magnetozones in the Namurian A through early Westphalian A interval. The results are dominantly to completely reversed in samples from the remainder of the Westphalian A and the Westphalian B, but because of the complication of varying degrees of remagnetization and an 800 m sampling gap it is not possible to verify the base of the Permo‐Carboniferous reversed superchron in this time period. Northward plate motion is inferred from an observed shallowing of inclinations upsection. A 5–7 cm/yr average poleward drift rate is calculated for this time period from these results, yielding a low‐latitude southern hemisphere paleogeographic position.

Microsaurs from the Westphalian B of Joggins, Nova Scotia

SUMMARY The order Microsauria was established by Dawson on the basis of specimens from the Joggins formation of Joggins, Nova Scotia. Restudy of material from this locality has revealed that the originally named species, Hylonomus lyelli, is actually a reptile. Numerous other specimens in this fauna are, in contrast, microsaurs as the term is currently used, i.e. lepospondyl amphibians. These forms show no significant similarities with early reptiles. Three genera are related to the Permian gymnarthrids and two to the genus Tuditanus from Linton, Ohio. Other material cannot be placed in any previously described group. Comparison is made with three related genera from the Czechoslovakian gas-coal, described earlier by Fritsch. All of these genera were apparently terrestrial, with well-developed limbs.