Boss Point Research Articles

How I Learned to Stop Worrying about Heavy Metal and Love Labor Journalism

How I Learned to Stop Worrying about Heavy Metal and Love Labor Journalism

Chemostratigraphy of Cumberland Group (Pennsylvanian) strata influenced by salt tectonics, Joggins Fossil Cliffs UNESCO World Heritage Site, eastern Canada

ABSTRACT The Pennsylvanian stratigraphy of the western Cumberland Basin has been influenced by salt tectonics, specifically the formation of the Minudie Anticline, a salt wall. South of the Minudie Anticline, along the shoreline of the Joggins Fossil Cliffs UNESCO World Heritage Site, the post–Boss Point Formation succession comprises an ∼ 3 km succession of strata assigned to the Little River, Joggins, Springhill Mines, and Ragged Reef formations. North of the Minudie anticline, the Grande Anse Formation lies in angular unconformity on the Boss Point and basal Little River formations. Biostratigraphic studies have not been able to discern whether the Grande Anse Formation is equivalent to all, or just one, of the Joggins to Ragged Reef units south of the salt wall (the Minudie Anticline). To further investigate the relationship of the Grande Anse Formation with the units along the Joggins shoreline, forty sandstone samples from the post–Boss Point Fm strata were selected for a chemostratigraphic study, using inductively coupled plasma mass spectrometry (ICP-MS) to determine major-element compositions. Transformed ICP-MS data, subjected to a Kruskal-Wallis test and post-hoc tests, show that there is no significant difference between Grande Anse and Ragged Reef formations in the mean values of almost all analyzed elements. In contrast, there are significant differences when comparing these two units and the older Little River, Joggins, and Springhill Mines formations in the case of elements usually encountered in detrital mineral phases (Si, Al, Ti, Na, and Fe). Sandstones of the Grande Anse and Ragged Reef formations show greater compositional maturity than the Little River, Joggins, and Springhill Mines formations. This trend is explained by a gradual overall change in paleoclimate from semiarid conditions during deposition of the Little River Formation to humid conditions during deposition of the Grande Anse and Ragged Reef formations, causing greater chemical weathering of the sediment. These findings indicate that > 2 km of sediment (Little River, Joggins, and Springhill Mines formations) accumulated south of the salt wall during the major episode of salt diapirism, followed by erosion of any topographic high associated with the salt wall, and accumulation of a further > 500 m of sediment (the laterally equivalent Ragged Reef and Grand Anse formations), all within a timespan of only ∼ 2 Myr.

Stratigraphy and sedimentology of the Pennsylvanian Grande Anse Formation, Cumberland Basin, eastern Canada: its relationship to salt tectonics and coeval strata of the Joggins World Heritage Site

The Cumberland Basin is one of several sedimentary basins composing the late Paleozoic Maritimes Basin complex of eastern Canada. Pennsylvanian salt tectonics in the Cumberland Basin caused two salt mini-basins to evolve on either side of the Minudie Anticline, a salt wall. South of the wall (Athol Syncline), along the Joggins World Heritage shoreline, an ∼3000 m succession of strata (Little River, Joggins, Springhill Mines, and Ragged Reef formations) accumulated conformably on the Boss Point Formation. North of the wall (Black Point sub-basin), the biostratigraphically equivalent, but mostly unstudied, ∼600 m thick succession of Grande Anse Formation lies in angular unconformity on folded and faulted Boss Point and basal Little River formations. Grande Anse Formation sedimentology indicates four lithofacies associations: floodplain (LA1), braided channel (LA2), sheet flood (LA3), and debris flow deposits (LA4). One possible model has the Black Point sub-basin with its own hydrological system, completely separated from the Athol Syncline. A low subsidence rate combined with the low sedimentation rate produced the ∼600 m thick sand- and mud-prone succession that was contemporaneous with the ∼3 km succession to the south. The second model proposes that north of the salt wall was exposed to erosion during accumulation of Joggins and Springhill Mines formation strata to the south. Subsequently, the sediment of the lithologically similar Ragged Reef and Grande Anse formations either (i) onlapped to the north, unconformably on the folded Boss Point; or (ii) unconformably–disconformably on the underlying strata after a period of time indistinguishable in the biostratigraphic record.

«Высвечивание» человека: экзистенциальный психоанализ Медарда Босса

The article gives a detailed view of the existential psychoanalysis of Swiss philosopher and psychologist Medard Boss. Based on the fundamental ontology of M. Heidegger, M. Boss criticizes the psychodynamic theories of the human psyche and turns to the analysis of the problem of human nature. A person, from the Boss's point of view, can only be understood as a person in the world (being-in-the-world). Through human existence, being can manifest itself as such. This is the destination of man. The basic existential category of M. Boss is the concept of "openness". The openness of existence allows us to get to know other people and respond to their own call to us. Existence is characterized by the Boss as joint, complicit, endowed with "presence", which is an ensemble of possibilities. M. Boss defines human existence through the existentials of spatiality, temporality, corporeality, eventfulness in the shared world, mood, historicity, and mortality. The realization of existence, according to the Boss, is possible only in the free choice that a person is initially endowed with, but which he may lose in the process of socialization. Blocking openness and freedom leads a person to neuroticism and illness. The article also analyzes the essence of the psychotherapeutic approach of M. Boss, which is based on the desire to understand a person through "highlighting" and openness. The article shows the opposition of existential analysis of the classical psychoanalytic tradition.

Post-Devonian movement on the Fredericton Fault and tectonic activity in the New Brunswick Platform, central New Brunswick, Canada

The Norumbega Fault system is traced from southern New England to Prince Edward Island, and its major strike-slip history is pre-Carboniferous. Carboniferous and later movements are less well constrained. Along the Fredericton Fault in western New Brunswick, offsets affect outcrops of Carboniferous strata in several ways. Revision of Carboniferous stratigraphy in this area using new miospore data and mapping of new exposures augmented by LiDAR imagery permits refinement of some of the post-Devonian movement history. The oldest post-Silurian unit recognized, the Longs Creek Formation, is fault-dissected and tightly folded, with faults and folds overlapped by the unconformity at the base of the upper Visean Shin Formation. The age of the Longs Creek Formation is uncertain and may be late Devonian to early Visean. Faults affecting the Shin Formation and Royal Road basalts are truncated by the unconformity at the base of the Bolsovian Minto Formation. Beneath this unconformity the presence of fault-bounded panels of vertical Langsettian strata (Boss Point and Deerwood formations) along the Fredericton Fault demonstrate late Visean to Serpukhovian, and post-Langsettian, pre-Bolsovian (Duckmantian) movements. At least three phases of movement can be seen affecting the Minto Formation. All the movement phases along the Fredericton Fault appear to be right-lateral strike-slip, except for one phase of post-Bolsovian left-lateral displacement.

Salt tectonics in an intracontinental transform setting: Cumberland and Sackville basins, southern New Brunswick, Canada

AbstractSalt tectonics have markedly influenced the rapid evolution of the Upper Palaeozoic Cumberland Basin of Atlantic Canada, including the ca. 5 km‐thick Mississippian – Pennsylvanian stratigraphic succession exposed along the UNESCO World Heritage coastline at Joggins, Nova Scotia. A diapiric salt wall is exposed in the Minudie Anticline to the north of the Joggins section on the Maringouin Peninsula of New Brunswick, which corresponds to the fault‐bounded northern margin of the Cumberland Basin. The salt wall is of Visean evaporites of the Windsor Gp that originally were buried by red‐beds of the Mabou Gp in the Serpukhovian, and later by fluvial and floodplain strata (Boss Point Fm, Cumberland Gp) in the Yeadonian (mid‐Bashkirian, Early Pennsylvanian). Folds and faults in the Boss Point and overlying basal Little River formations are truncated by an angular unconformity at the base of overlying red‐beds of the Grande Anse Fm. Re‐evaluation of the palynological data delimits the Grande Anse Fm as Langsettian, providing a tight constraint of less than 2 myr on the timing of deformation. Diversion of palaeoflows by the rising salt structure, noted in previous work on the upper Boss Point Fm, occurs to the north of the diapiric anticline. This is interpreted to signify the development of a mini‐basin on commencement of diapirism once a ~1.5 km‐thick succession of clastic strata had buried the salt. Faults and folds in the succession below the unconformity indicate an initial phase of dextral transpressive strike‐slip motion, which may have promoted halokinesis. Reverse faults indicate shortening associated with northward development and overturn of the Minudie Anticline during transpression; subsequent normal faulting was associated with collapse of the sediment pile and underlying salt structure.

Sedimentology and stratigraphy of the type section of the Pennsylvanian Boss Point Formation, Joggins Fossil Cliffs, Nova Scotia, Canada

<p style="margin: 0in 0in 0pt;"><span style="font-family: 'Minion Pro','serif';"><span style="font-size: medium;">The 1125-m-thick type section of the Pennsylvanian Boss Point Formation is well exposed along the shore of the Bay of Fundy in Nova Scotia. We provide the first comprehensive account of the entirety of this formation, which comprises nearly one-third of the stratigraphic thickness of the Joggins Fossil Cliffs UNESCO World Heritage Site. The basal Chignecto Bay Member (0–91.5 m) is composed of redbeds, single-storey channel bodies with northerly paleoflow, and thin palustrine limestones. The middle Ward Point Member (91.5–951.7 m) contains up to 16 megacycles composed of alternations between thick packages of braided fluvial sandstone and fine-grained deposits. Although regional studies of the Boss Point Formation suggest that the fine-grained deposits are largely composed of lacustrine sediments, these intervals consist largely of poorly drained and well-drained floodplain deposits in the type section. The facies variations and southeast-directed paleoflow in the Ward Point Member record modest uplift associated with the growth of the salt-cored Minudie Anticline. The North Reef Member (951.7–1125 m) is composed of redbeds and two distinctive multistorey channel bodies. This uppermost member records a shift to more arid, oxidizing conditions, was the precursor to a major phase of salt withdrawal, and represents a transition to the overlying Little River Formation. The sedimentological framework, revised stratigraphy, and detailed measured section and map will provide a foundation for future study of this remarkable Pennsylvanian exposure.</span></span></p>

Role of vegetation in shaping Early Pennsylvanian braided rivers: Architecture of the Boss Point Formation, Atlantic Canada

AbstractVegetation is a major driver of fluvial dynamics in modern rivers, but few facies models incorporate its influence. This article partially fills that gap by documenting the stratigraphy, architecture and palaeobotany of the Lower Pennsylvanian Boss Point Formation of Atlantic Canada, which contains some of the Earth's earliest accumulations of large woody debris. Braided‐fluvial systems occupied channel belts of varied scale within valleys several tens of metres deep and more than 12 km wide, and their deposits predominantly consist of sandy and gravelly bedforms with subordinate accretionary macroforms, high flow‐strength sand sheets and rippled abandonment facies. Discrete accumulations of clastic detritus and woody debris are up to 6 m thick and constitute at least 18% of the in‐channel deposits; they represent lags at the base of large and small channels, fills of minor channels and sandy macroforms that developed in central positions in the upper parts of channel fills. Sandstones with roots and other remnants of in situ vegetation demonstrate that vegetated islands were present, and the abundance of discrete channel fills suggests that the formation represents an anabranching, island‐braided sandbed river, the earliest example documented to date. Although some sphenopsid and lycopsid remains are present, most woody fragments are derived from cordaitalean trees, and the evolution of this group late in the Mississippian is inferred to have exerted a significant influence on fluvial morphodynamic patterns. The formation records a landscape in which active channel belts alternated with well‐drained floodplains colonized by dense, mature forests and local patches of pioneering, disturbance‐tolerant vegetation. Lakes and poorly drained floodplains dominated by carbonate and organic deposition, respectively, were also present. A large supply of woody debris triggered channel blockage and avulsion, and active channel margins and islands within the channel belts were initially colonized by pioneer vegetation and subsequently stabilized by large trees. A similar alternation of stable and unstable conditions is observed in modern braided rivers actively influenced by vegetation.

Discussion on ecology of earliest reptiles inferred from basal Pennsylvanian trackways Journal , Vol. 164, 2007, 1113–1118

David Keighley, John Calder, Adrian Park, Ronald Pickerill & John Waldron write: In a recent article, Falcon-Lang et al . (2007, p. 1113) claim ‘trackways representing the earliest evidence for the origin of reptiles (amniotes) are reported from the basal Pennsylvanian Grande Anse Formation, New Brunswick’. We note inaccuracies in the paper and bring attention to various lines of evidence, any one of which casts serious doubt on their claim. ### Age of the Grande Anse Formation. Falcon-Lang et al . (2007, p. 1113) report a location at Shepody Bay, ‘on the eastern side of the Maringouin Peninsula, New Brunswick’ (actually located on the western side, Fig. 1) that preserves interface sedimentary structures that they interpret as amniote trackways. The authors infer an earliest Langsettian (earliest Westphalian), or possibly latest Namurian, age for the Grande Anse ‘Formation’ at this locality (the unit is not formally defined). This interpreted age of the strata was based on two lines of evidence: (1) a palynological age determination from an unpublished report; (2) its reported stratigraphic position equivalent to the Little River Formation of Nova Scotia, conformably overlying the Boss Point Formation. Fig. 1. Map of the Maringouin peninsula and nearby Joggins area, New Brunswick and Nova Scotia, incorporating elements of Gussow (1953), Ryan et al . (1990), St. Peter & Johnson (1997) and Calder et al . (2005). (1) The report cited by Falcon-Lang et al . (2007) actually states that the spores indicate an age ‘no older than the early middle Langsettian’ (Dolby 1999, p. 43). Therefore, the Grande Anse Formation would not be of identical biostratigraphic age to that reported for the Little River Formation, which is of probable late Namurian to basal Westphalian (basal Langsettian) age (Calder et al . 2005). Regardless, Upper Palaeozoic strata in eastern Canada (Fig. 2) lack many of the stratigraphically diagnostic marine index fossils and European miospores recorded in the literature (Calder 1998; Utting et al . 2005) and so it is not currently possible to unequivocally constrain the age of the Grande Anse strata. In addition, recent recognition of rapid Mississippian stratigraphic inversions in SE New Brunswick (e.g. Park & St. Peter 2005) has supported interpretations that at least some spore assemblages in the region are entirely reworked (e.g. Dolby 2004). Fig. 2. Summary of mid-upper Carboniferous stratigraphy for the Maritime Provinces. For brevity and clarity, only formation and group names from this discussion have been included. Data are a compromise of numerous sources and so, although the stratigraphic …

Vegetation ecology of Early Pennsylvanian alluvial fan and piedmont environments in southern New Brunswick, Canada

The vegetation ecology of Pennsylvanian upland/dryland regions is poorly known, despite its evolutionary significance. Here, fossil plant assemblages are described from well-drained alluvial fan/piedmont deposits in the uppermost Boss Point and Tynemouth Creek formations (late Yeadonian–Langsettian), southern New Brunswick. Beds record the northward building of a large alluvial fan complex over alluvial plain deposits in response to near-continuous sourceland uplift. Proximal alluvial fan environments, characterized by sheetfloods and braided streams, were dominated by large cordaitalean trees, medullosan pteridosperms, ferns, and calamiteans. Distal alluvial fan environments, where braided stream and leveé/splay sedimentation predominated, were covered by similar vegetation, together with lycopsids in localized poorly drained depressions. Calamitean thickets were particularly widespread in rapidly aggrading settings on the distal fan. Well-drained alluvial plains beyond the fan toe were characterized by axial braided rivers containing cordaitalean trunks transported from proximal settings. Piedmont vegetation is otherwise poorly resolved. All studied plant assemblages are of low- to medium-diversity, and dominated by the remains of a single group, cordaitalean seed plants. Such dominance-diversity characteristics, together with the presence of charcoal, the product of wildfire, imply that Pennsylvanian upland/dryland vegetation experienced water-stress and that the seed habit was integral to successful colonization.

Paleomagnetism of the Distal Member of the New Glasgow Formation, Nova Scotia, Canada: New Constraints on Magnetic Polarity Stratigraphy near the Base of the Kiaman Superchron

The ca. 315–260‐Ma Kiaman Reversed (Permo‐Carboniferous) Magnetic Superchron is an important time marker that can be used for correlation of stratigraphic sequences from a local to a global scale. Earlier workers, from a paleomagnetic study of the Joggins stratigraphic section of the western Cumberland Basin of Nova Scotia, demonstrated that the base of the superchron lies above redbeds of the lowermost portion of the late Namurian–Westphalian A Boss Point Formation. Although a detailed sequence of reversals was observed below this point, no normal magnetic polarity zones were recognized above it. In our study, samples were collected from redbeds of the distal member of the Westphalian A New Glasgow formation of the eastern Cumberland Basin, which directly overlie the gray sandstones of the Boss Point Formation. Most sampling sites carry a normal polarity magnetization, probably acquired at about the time of deposition. Therefore, the base of the Kiaman Reversed Superchron lies within or above the New Glasgow formation. Either the top of the Boss Point Formation is diachronous between the two areas, or, more likely, the base of the superchron is significantly higher in the stratigraphic section than previously recognized, a conclusion that is important for both intrabasin and intercontinental stratigraphic correlations. It implies that the pattern of pre‐Kiaman magnetic reversals reported from below the Boss Point Formation in the Joggins section is significantly older than previously thought and, therefore, cannot be used for comparison with magnetic reversal patterns that closely underlie the base of the superchron at other localities in the Cumberland Basin or on other continents.

Alternating Braidplain and Lacustrine Deposition in a Strike-Slip Setting: The Pennsylvanian Boss Point Formation of the Cumberland Basin, Maritime Canada

ABSTRACT The Boss Point Formation was deposited in the Cumberland Basin of southeastern New Brunswick and northern Nova Scotia during the early Pennsylvanian. The basin is bounded to the northwest and south by strike-slip faults, active during the Pennsylvanian. The Boss Point comprises two main fades associations: sandy braidplain (BFA) and muddy lacustrine (LFA), the abrupt alternation of which allows 16 depositional megacycles to be defined. The LFA forms units 50 m thick that rest sharply but nonerosively on braidplain sandstone. In some instances the contact can be traced for over 12 km perpendicular to paleoflow. Commonly dunes and ripples are preserved in relief beneath lacustrine mudstone, implying rapid but very low-energy flooding of t e braidplain. The BFA comprises multistory channel sandbodies 90 m thick, separated from the underlying LFA by sixth-order surfaces with up to 15 m of erosional relief. The erosion surfaces are commonly overlain by spectacular mudstone breccias and boulders that reflect deep erosion and rotational slumping into channels cut into, and sometimes right through, lacustrine deposits. BFA packages are internally partitioned by fifth-order erosion surfaces into individual channel-fill units, commonly about 5 m thick. The BFA is dominated by trough-cross-bedded fine to lower medium sandstone. Conglomerate, pebbly sandstone, and ripple-laminated and planar-laminated sandstone are minor components. Rare mud-filled abandoned channels suggest a mean width and de th of > 160 m and 4.8 m, respectively. The dominance of trough cross-bedding suggests relatively deep channels, whose banks may have been maintained by a dense vegetation cover. Repeated channel avulsion and flood-related erosion resulted in a rock record dominated by deep-channel and flood-stage deposits; bartop facies were rarely preserved. Channel dimensions, lateral consistency of facies, paucity of muddy channel plugs, and regionally consistent paleoflow suggest deposition on a braidplain. The distribution of conglomerates indicates a local gravel source area in the Caledonia Highlands to the northwest, but much of the sand is likely to have been sourced far to the southwest. The Boss Point falls into two sharply disjunct paleoflow domains, one directed to the north and northeast and the other to the east and southeast, separated by the Harvey-Hopewell fault zone. The absence of an adequate watershed between the two domains strongly suggests tectonic juxtaposition involving ?several tens of kilometers of sinistral offset.

Tectonic Event Stratigraphy in a Fluvio-Lacustrine, Strike-Slip Setting: The Boss Point Formation (Westphalian A), Cumberland Basin, Maritime Canada

ABSTRACT The Boss Point Formation (Westphalian A) was deposited in a rapidly subsiding strike-slip basin. The formation, about 800 m thick, comprises alternate braidplain and lacustrine associations. Sixteen megacycles, defined by sharp but nonerosive lacustrine flooding surfaces, each comprise a lower lacustrine and an upper braidplain package. Braidplain deposits invariably scour deeply into lacustrine strata. The lacustrine association consists of very fine sandstone, mudstone, claystone, coal, and limestone deposited in shallow, hydrologically open freshwater lakes. Lakes were filled by small, elongate, river-dominated deltas, and by suspended and biogenic sediment. Sand-rich deltaic represent mouth bar, subaqueous levee, crevasse channel and splay, and straight and sinuous distributary-channel subenvironments. Evidence of wave reworking is very scarce. Interdeltaic areas accumulated platy gray mudstone. As interdistributary bays aggraded to water level they were subject to oxidation and pedogenic modification, forming bright colors, prismatic (desiccation) fabrics, pseudo-anticlines, and calcretes. Thin but laterally extensive (possibly up to 40 km) abandonment facies comprising black, organic-rich mudstones, coals, and ostracod limestones suggest periods of clastic starvation. Dunes, current ripples, and rarely adhesion ripples are common on the top surfaces of braidplain sandstone packages, preserved beneath a blanket of lacustrine mudstone. Rare oscillation ripples attest to localized reworking of the fluvial sand during or soon after flooding. Flooding surfaces can be traced for 12 km, and possibly up to 40 km, and are attributed to instantaneous subsidence along the northwest margin of the basin during major earthquakes. One locality preserves evidence of abrupt, 180° paleoflow reversals above and below a lacustrine unit. This is interpreted to record abrupt basin tilting, first to the northwest, forming a lake that filled from the southeast, followed by tilting to the southeast. We interpret Boss Point megacycles to reflect the interaction of episo ic tectonic subsidence with longer-term changes in sediment supply controlled by cyclical climatic variation in the Milankovitch band. During periods of pronounced wet-dry seasonality when clastic supply was high, sandy and gravelly braidplain deposits prevailed, and any lakes that formed by earthquake-related subsidence were rapidly filled. During more humid periods, higher vegetative cover greatly reduced clastic supply, and lakes persisted for many thousands of years. Hydrologic changes accompanying the transition from relatively humid to strongly seasonal wet-dry periods might have resulted in the deep fluvial erosion observed at the base of each braidplain package.

Early diagenetic spherulitic siderites from Pennsylvanian palaeosols in the Boss Point Formation, Maritime Canada

ABSTRACTThe Boss Point Formation of Maritime Canada comprises alternating successions of braidplain sandstone, lacustrine mudstone, and lacustrine fluvio‐deltaic sandstone and mudstone. These rocks were deposited within an active strike‐slip basin during the early Pennsylvanian (Westphalian A), at a palaeolatitude of 8°S. Palaesols comprise a small but distinct proportion of the formation, and typically occur at the tops of fining upward sandstone‐siltstone cycles.Spherulitic siderites from the Boss Point Formation occur within sandy and silty palaeosols. They occur as ‘large’ (>200 μm) and ‘small’ (<200 μm) diameter spherulitic nodules within calcrete, and show either a radially arranged ferroan calcite and siderite spar morphology, or contain a core of ferroan calcite, surrounded by a later formed sheath of siderite. Analytical data indicate that with respect to Ca‐Mg‐Mn, wide compositional variation occurs within the siderites. The Boss Point Formation siderites are similar to, but contain less Ca for a given Mg/Mn ratio, than previously published siderite compositional data. Published data, together with the results from the Boss Point Formation, indicate that a continuum exists in freshwater siderites, between the relatively Mn‐depleted and the Mg‐enriched analytical fields that were previously reported.The relatively low Ca values determined in the Boss Point Formation samples reflect the general lack of calcium in the sedimentary basin during sedimentation. Both chlorite and smectite clays may have been important sources of iron. It is concluded that the spherulitic siderites are eogenetic, and formed within small anoxic ponds rich in organic matter, under reducing and low dissolved sulphate conditions. With time these pools dried up, ferroan calcite precipitating as calcrete nodules around the earlier formed siderite spherulites.

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.

An ornamented mudstone cavity, Boss Point Formation, Sackville, New Brunswick, Canada: evidence for mud intrusion and rheoplasis

ABSTRACTAn ornamented, dome‐shaped cavity, partially filled with mudstone, 4 m in diameter at its circular base and 1 m in height occurs in fluvial sandstone of the Carboniferous Boss Point Formation near Sackville, New Brunswick, Canada. The cavity formed by differential weathering and erosion of the mudstone. Its origin is enigmatic though its size, shape and relationship to the underlying mudstone bed on which it rests suggest a diapiric origin for the mudstone that filled it. On the other hand, the ornamentation on the cavity surface includes flute moulds, suggesting an erosional origin for the domal structure.Of the four principal hypotheses for its origin the one preferred by the authors involves formation by diapiric intrusion of semi‐fluid mud into liquefied sand, soon after deposition. The ornamentation on the cavity surface would have formed as part of the intrusion process. Structures akin to flute moulds have been produced experimentally in support of this interpretation by differential flow across a cement‐mix‐mud interface in a flow box and also by diapiric intrusion of mud in a soft cement mix. By analogy the flute moulds on the cavity surface could have been formed in the same way. By this interpretation, primary sedimentary processes need not be invoked to explain their occurrence on either this cavity surface or on the numerous other mudstone cavity surfaces that are ubiquitous in the Permo‐Carboniferous of eastern Canada. Results of this study have important implications with respect to the potential diversity of origins of flute moulds in general.

Structural and sedimentary history of the Quaco Head area, southern New Brunswick

Remapping of the Quaco Head area of southern New Brunswick has revealed a more complex structure than had been previously documented. The structure is dominated by two major thrust faults that dip to the south and southeast at between 35 and 45°. The lower (younger?) thrust emplaces Precambrian basalts and tuffaceous siltstones (Coldbrook Group) over alluvial sediments of the Boss Point and Tynemouth Creek formations (Westphalian A–B). Resting unconformably on the upper surface of the basalt is a thin layer (≤ 10 m) of marine, basal Windsor Group limestone, disconformably overlain by alluvial conglomerates of inferred Hopewell Group age. This sequence is truncated by an older, southeast-dipping thrust fault, to the southeast of which lie Hopewell conglomerates overturned towards the west and northwest. The latter sequence probably forms the lower limb of a large recumbent fold. Folding and thrusting in the Quaco Head area may have begun during Westphalian B times, although major movement was probably post-Westphalian C and occurred contemporaneously with dextral strike-slip movement on the Minas geofracture. Following this Alleghenian–Variscan deformation, the area underwent deep erosion prior to the deposition of a thick sequence of Triassic alluvial sediments. The more southerly reverse fault was reactivated as a normal fault during a phase of late Triassic or Jurassic faulting along the Bay of Fundy that was probably related to early Atlantic rifting.

Tectonic Effects on Meandering River Deposits, Carboniferous, Nova Scotia, Canada: ABSTRACT

Sediments of the Boss Point, Port Hood, and Parrsboro Formations (Carboniferous) of Nova Scotia were deposited on alluvial plains in tectonically active basins bounded by strike-slip faults. Some basins contain over 1 km of strata of this age. Fining-upward fluvial channel sandstones are about 20 m thick and are composed of a vertical sequence of basal conglomerate, trough cross-beds, ripple lamination, and siltstone. Large-scale lateral accretion surfaces are present and the sandstones are interpreted as meandering river deposits. Flood-plain sediments include crevasse splay sandstones, rooted mudrocks, thin coals, and lacustrine deposits. The channel sandstones are stacked vertically and many form thick sandstone packages. One 1-km thick sequence, for example, consists of over 75% channel sandstone. There are similarly thick, laterally equivalent, sequences of flood-plain sediment with few or no channel sandstones. It appears, therefore, that meander belts were restricted in their positions for long periods, allowing the unusually thick sequences of channel and coeval overbank sediment to accumulate. The variation from the classic meander-belt model, in which avulsion randomly distributes the meander belts across the alluvial plain through time, was presumably due to differential subsidence rates which caused the meander belts to be restricted to the areas of higher subsidence, thus retarding avulsion frequency. End_of_Article - Last_Page 955------------

Flute casts and related structures on moulded silt injection surfaces in continental sandstone of the Boss Point Formation: southeastern New Brunswick, Canada

Flute, load and groove casts occur widely at the sharp Interfaces of siltstone diapirs, Injection lenses, and pods la fluvial sandstone of the Boas Point Formation of southeastern New Brunswick. These concordant and discordant Injection features range from approximately 20 centimetres (pods) to many metres (injection lenses) In diameter. They are confined to "brecclform Intervals" that can be traced along strike and dip for a hundred metres or more.
 
 The flute, load and groove casts on the Injection surfaces, have evidently not been formed by any primary sedimentary process but are the result of liquefaction, sediment Injection and flow moulding during post-depositonal compaction of the strata. The term "rheoplasis" Is proposed to denote this process, and the general term "rhaoplastic structures" or "rheoplasts" refers to the range of sole-marking like structures formed as a result of this process.
 
 The realization that flute costs can form as a result of post-depostional processes is of great significance In the classification of sedimentary structures and the Interpretation of depositional environments and attendant sedimentary processes.
 
 RÉSUMÉ
 Au sud-est du Nouveau-Brunawlck, dans les grès fluvlatiles de la formation de Boss Point, on peut voir de nombreax exemples de flûtes, empreintes de charge et cannelures aux interfaces distlncts de diapirs de siltstone, de lentilles d'injection, de mottes et de loupes. Ces éléments d'injection sont concordance ou discordants et possèdent un dlamètre allant de 20 cm (pour les loupes) jusqu'à plualeurs mètres (pour les lentilles d'injection). Ils sont égalemenr restraints à des "intervalles bréchiques" que l'on peut suivre sur des cencaines de mètres et plus, le long de la direction et du pendage de la stratification.
 
 Les flûtes, cannelures et empreintes de charge que l'on retrouve aur les surfaces d'injection ne résultent évideoment pas d'un processus sédimentalre primaire male plutôt de la liquéfaction, de l’injection du sédiment et du moulage des coulées durant la compaction après la déposition de la strate. Pour marquer ce procede, on propose le terme "rhéoplasle" alors que le terme plus global "structures rhéoplastiquea" (ou "rhéoplaates") a'appllque lux empreintes de toutes sortes qui résultent de ce même procédé et que l'on retrouve sur la surface inférieutre d'une strate.
 
 La classification des structures sédimentaires ainsi que l'interprètation des envlronnements de déposition et des procédée sédiment aires connexes aeront grandetnent influenced par le fait que des flûtes peuvent résulter d'un procédé post-déposltionnel.
 
 [Tradult par le Journal]

Cupriferous bogs in the Sackville area, New Brunswick, Canada

Abstract Two cupriferous bogs in the Sackville area of New Brunswick, Canada, are described. The organic matter (muck) in these bogs contains from 2 to 6% Cu, derived from cupriferous springs that carry copper in amounts ranging from 0.005 to 1 ppm. The source of the copper in the springs is unknown, but the metal probably originates from the leaching of cupriferous (chalcocitic) deposits in grits and conglomerates at the base of the Boss Point Formation of Carboniferous (Pennsylvanian) age. The copper occurs in the muck as copper humate(s), the precise chemical characterization of which is unknown. Examples of copper bogs related to copper mineralization in many parts of the world are reviewed, and it is pointed out that such bogs are good geochemical indicators of cupriferous deposits. The moss, Pohlia nutans , grows in the springs in the copper bogs and in other wet sites in the area where large concentrations of copper occur. This moss is tolerant to large amounts of available copper and markedly accumulates the metal. When slightly chlorotic Pohlia nutans may indicate the presence of higher than normal amounts of copper.