Lithostratigraphy of the Late Devonian-Early Carboniferous Horton Group of the Moncton Subbasin, Southern New Brunswick

MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 11

Lithostratigraphy of the Late Devonian-Early Carboniferous Horton Group of the Moncton Subbasin, southern New Brunswick

D.C, CanJbeji and R.K. Pj^ckejilAA, D&pajiJLmejit o/ §e.o£ogy, llrvivejLA-ity o/ New B/uiriAuxick, T/iejdbejii.ci.on., N,B, £38 5A3

The threefold subdivision of the Late Devonian - Early Carboniferous Horton Group in the Moncton Sub- basin of southern New Brunswick conforms to the original description and subsequent adoption of the group elsewhere in the Maritimes Basin. The Horton Group consists of the Memramcook, Albert and Moncton formations, the Moncton Formation having previously been regarded as a group. The Memram- cook Formation rests unconformably on pre-Carboniferous basement and is conformably overlain by and in part the lateral facies equivalent of the Albert Formation. The Albert Formation contains five variably developed members (both spatially and, in part, temporally): the Dawson Settlement, Frederick Brook, Hiram Brook, Round Hill and Gautreau members. Of these, the Round Hill and Gautreau members have previously been the subject of much stratigraphic debate but are herein proposed simply as members of the Albert Formation. The formally proposed Moncton Formation is subdivided into a lower Weldon Member and an upper Hillsborough Member; where the contact can actually be defined it is un- conformable. The Albert Formation - Weldon Member contact is conformable and transitional. The Hillsborough Member - Windsor Group contact is marked by an abrupt facies change where Windsor Group strata are marine as distinct from non-marine in origin. Le groupe Horton (DSvonien supSrieur - CarbonifSre infSrieur) que l'on retrouve dans le sous-bassin de Moncton au sud du Nouveau-Brunswick est divisg en trois formations, conformSment 8 la description originale telle qu'adoptSe ailleurs dans le bassin sSdimentaire des Maritimes. Le groupe Horton comprend les formations de Memramcook, Albert et Moncton (la formation de Moncton 6tait autrefois consid£r£e comme un groupe). La formation de Memramcook repose en discordance sur un socle pr6-CarbonifSre et est recouverte de fa?on concordante par la formation d'Albert. La formation de Memramcook est egalement en partie un faciSs lateral de la formation d'Albert. La formation d'Albert compte cinq membres dont 1'emplacement a vari6 dans l'espace, et em partie, dans le temps: les membres Dawson Settlement, Frederick Brook, Hiram Brook, Round Hill et Gautreau. Les membres Round Hill et Gau- treau, qui par le pass6 ont soulevS maints dSbats stratigraphiques, sont ici pr6sent6s comme membres de la formation d'Albert. La formation de Moncton, pr6sentSe de fagon officielle, est divis&e en un membre infgrieur, Weldon, et un membre supgrieur, Hillsborough; 13 oQ il peut 6tre indenting, le contact est discordant. Le contact concordant entre la formation d'Albert et le membre Weldon en est ggalement un de transition. Le contact entre le membre Hillsborough et le groupe Windsor n'est marqug par un brusque changement de faciSs que 13 oil les strates du groupe Windsor sont distinctement d'origine marine, plutot que non-marine. [Traduit par le journal] INTRODUCTION to the southeast by the pre-Carboniferous The Late Devonian-Early Carboniferous basement of the Caledonia Uplift and to Horton Group of Bell (1927, 1929) in the the northwest by the Kingston-Indian Maritimes Basin (Williams 1974) of east- Mountain Uplift. The eastern end of the ern Canada represents the basal group subbasin is bounded, and in part bifur- of a succession of molasse sediments cated, by the Westmorland Uplift, the which accumulated in an essentially non- existence of which is clearly revealed marine successor-type strike-slip basin when isopach data for the Horton Group (Bradley 1982). Present-day distribution are examined (Fig. 2). During deposition of. the Horton Group represents the of the Horton Group, the Kingston and erosional remnants of a complex series Westmorland uplifts were passive features of subbasins and arch or uplift struc- whereas the Caledonia Uplift provided an tures which controlled the spatial deve- important and continuous supply of detri- lopment of the strata. In southern New tus (Pickerill and Carter 1980). Brunswick, Horton Group strata accumu- Research in the Horton Group of the lated in the Moncton Subbasin (Fig. 1) and Moncton Subbasin has revealed that the are characterized by alluvial fan, fluvial- existing stratigraphic nomenclature is deltaic and lacustrine sediments. The unsatisfactory. Traditionally the group has Moncton Subbasin trends northeast, nar- been subdivided into a basal Memramcook rows to the southwest, and is bounded Formation (Norman 1941a, 1941b), a medial Albert Formation (Norman 1932) MARITIME SEDIMENTS AND ATLANTIC GEOLOGY and an upper unit referred to as Moncton 21, 11-24 (1985) 0711-U50/85/010010-14$3.I0/0 12 Carter and Pickerill

Fig. I - Location of the Moncton Subbasin, southern New Brunswick and the Caledonia and Kingston uplifts (modified after Macauley et al. 1984). Group (Norman 1932) comprising a lower only as a result of different workers with Weldon Formation and an upper Hills- different professional backgrounds adopt- borough Formation as shown in Table 1. ing different stratigraphic philosophies, Clearly, this scheme contravenes all but also as a result of the complex existing codes of stratigraphic nomen-, spatial and temporal facies relationships clature. To alleviate these difficulties we existing within the Albert Formation. In herein propose to retain the threefold this paper we identify some of these stratigraphic subdivision of the Horton nomenclatural problems, briefly review Group but formally propose that the existing nomenclature, formally propose Moncton Group be relegated to forma- that the Gautreau Formation of Norman tional status and the Weldon and Hills- (1932) and Round Hill Formation of Mc- borough formations to member status Leod (1980) be included as members of within the Moncton Formation. This the Albert Formation and outline areas scheme conforms to existing stratigraphic for future and more detailed stratigraphic codes and, as we will demonstrate, is a research. more realistic subdivision of the litho- It must be emphasized that in this stratigraphy. paper we do not propose additional strati- Of equal importance is the confusion graphic units within the Horton Group that has arisen over the last two decades of the Moncton Subbasin; rather, we or so with respect to the internal strati- place previously established units into a graphic nomenclature of the Albert For- more workable and realistic lithostrati- mation. This confusion has arisen not graphic framework which conform to MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 13

Fig. 2 - Gravity, aeromagnetic and isopach data for the Horton Group in the Moncton Subbasin. Gravity data shown in dip/strike and dot pattern and is in milligals. Aeromagnetic data shown in line and dot pattern and is in gammas. Isopach data shown in solid line and scale is in thousands of feet. Vertical line ornament outlines presumed Horton gravity anomalies (= salt bodies). existing codes of stratigraphic nomen- micaceous conglomerates, sandstones, clature. As this paper places more siltstones and shales with minor green emphasis on the Albert Formation, we intervals. The upper boundary of the for- initially discuss the underlying Memram- mation is generally conformable and cook and the overlying Moncton forma- gradational with the overlying Albert For- tions. Figure 3 is a location map of all mation; however, local disconformities sites referred to in the ensuing text or were suspected by Greiner (1962). The in the additional figures and Table 1. suspected disconformities, however, are More detailed sedimentological descrip- based on the absence of the coarse basal tions and facies interpretations of the unit of the Albert Formation (Greiner Horton Group in the Moncton Subbasin 1962) and such relationships can equally, can be found, for example, in Gussow and more readily be explained by trans- (1953), Schroder (1963), Popper (1965), gressive overlap of the finer grained McLeod and Ruitenberg (1978), Pickerill Albert facies (cf. Pickerill and Carter and Carter (1980), Macauley and Ball 1980). The suspected disconformities are (1982), Pickerill et al. (1985) and refer- therefore considered as unnecessary and ences therein. unsubstantiated. Due to the interdigita- ting nature of color types, the Memram- MEMRAMCOOK FORMATION cook/Albert contact has traditionally been arbitrarily placed where either red The Memramcook Formation, introduced or grey coloration becomes dominant. formally by Norman (1932), rests uncon- Miospores from the Memramcook Forma- formably on pre-Carboniferous basement tion indicate a Late Devonian (Famen- and is composed of a series of red, often nian) age (Hacquebard 1972, Barss et al. distinctively purplish red, arkosic and 1979). 14 Carter and Pickerill

Outcrop and drill data suggest that favoured. Strata of the Memramcook For- the formation is, on the whole, present mation are representative of a post- throughout the Moncton Subbasin, though orogenic redbed molasse facies formed its thickness varies considerably from by deposition of sediments in piedmont c. 140m in the southwest to more than alluvial fan(s) and associated braided 2350m in the belt near Lutz Mountain fluvial environments. (Gussow 1953), adjacent to the Kingston Uplift. In its type area near Memram- MONCTON FORMATION cook Village, the Memramcook Forma- (Weldon and Hillsborough members) tion is c. 500m in thickness (Norman Since formally defined by Norman 1941a, 1941b). An important exception to (1941a, 1941b) the Moncton "Group" has this generalization occurs in the Rosevale been the subject of a complex and varied area where the Memramcook Formation stratigraphical debate but has consis- is absent, and instead, the Albert Forma- tently been divided into two units, herein tion rests directly and unconformably on formally proposed as the Weldon and pre-Carboniferous basement strata of the Hillsborough members. Thickness of the Caledonia Uplift (Gussow 1953, Greiner "group" is difficult to estimate because 1962). This implies either a period of pre- of the few well-exposed and structurally Albert Formation erosion of the Memram- simple sections available. However, in cook Formation in this area, or alter- general, it thickens northward away from natively, transgressive overlap of the the Caledonia Uplift from as little as Albert Formation onto basement strata. c. 100m near Upham to as much as 2000- Because the transition between Memram- 2400m southwest of Sussex (Gussow cook and Albert strata is everywhere 1953). Thickness of individual members else gradational, the latter suggestion is also varies accordingly.

Fig. 3 - Simplified map of the Sussex-Moncton area, southern New Brunswick, illustrating locations referred to in the text and in Figures 1, 2 and Table 1. TABLE 1

Stratigraphic nomenclatural schemes of the Albert Formation, Moncton Subbasin, southern New Brunswick (see text for details) 16 Carter and Pickerill

There is little doubt that these two contacts are exposed the two members units are mappable, can normally be dif- are easily differentiated. ferentiated and belong to a single pack- Gussow (1953) regarded the Weldon age of redbed strata which separate Member as the upper unit of the Horton underlying grey strata (=the Albert For- Group and the Hillsborough Member as mation) from the overlying marine lime- the lower unit of the overlying Windsor stones/evaporites and associated strata Group. However, Kelley (1970) and van of the Windsor Group. If, however, these de Poll (1972) included both the Weldon strata are to be included within the Hor- and Hillsborough members within the Hor- ton Group, which seems reasonable when ton Group in order to satisfy Bell's (1929) considering the threefold subdivision of original definition of the Windsor Group, Carboniferous strata elsewhere in eastern the base of which was placed at the Canada (see Knight 1983 for review), then lowermost marine unit. More recently, the term Moncton "Group" should be McCutcheon (1981) also removed the abandoned. Thus to conform with existing Hillsborough Member from the Windsor stratigraphic codes, we formally propose Group. Additionally, Schroder (1963) sug- that the term Moncton Formation should gested that the term Moncton Group be be adopted for this redbed sequence and dropped but the Weldon and Hillsborough the Weldon and Hillsborough be regarded units retained since they were mappable as members of this formation (cf. Kelley units separated, at least locally, by an 1967, 1970; van de Poll 1972). unconformity. Kelley (1970) and van de Poll ( 1972) suggested, as we do herein The basal Weldon Member consists pre- more formally, that the Weldon and Hills- dominantly of interchannel, overbank and borough be given member status within floodplain deposits of red conglomerate, a newly proposed Moncton Formation. sandstone, siltstone and mudstone and the Hillsborough Member comprises We propose, therefore, that the Weldon coarser grained red fluvial channel and and Hillsborough members be included in alluvial fanglomerates and a basal vol- the Horton Group to conform to the canic ash bed. The contact of the Weldon original description and definition of the Member with the underlying Albert For- group by Bell (1929). Not only does this mation is generally conformable and conform with the majority of recent sug- gradational, similar to that of the Albert- gestions by workers in the Moncton Sub- Memramcook contact. The Albert-Weldon basin (see above) but also the scheme is contact is defined; (1) by the occurrence more consistent with more recent work of a basal Weldon conglomerate overly- in other parts of the Maritimes Basin ing finer grained Albert lithofacies (ii) (e.g. Anderle et al. 1979, Knight 1983). by dominance of color (lowest red bed, This work places the base of the Wind- highest grey bed) in coarse- or fine- sor-Codroy groups at the first occur- grained lithofacies, (iii) where the Weldon rence of marine beds within the overlies the more easily recognizable sequence. Additionally, McCutcheon (1981) Gautreau Member (as defined herein) of has reported that the contact between the Albert Formation. Hillsborough and Windsor strata is struc- Contact of the Weldon and Hillsborough turally conformable but not gradational members is not so straightforward. In and that rocks typical of a transition places there is an upward transition from a terrestrial to a marine environ- from fine- to coarse-grained strata repre- ment are absent. Because strata of the senting a conformable succession. At such Windsor Group simply represent a marine localities the Moncton Formation cannot transgression into the subbasin, we sus- be easily subdivided (Gussow 1953, pect that this latter conclusion is prob- Greiner 1962). Elsewhere, the Weldon ably an oversimplification and that, in Member has been eroded and structurally part, marine Windsor Group strata are deformed before deposition of the Hills- in fact lateral temporal equivalents of borough Member (Gussow 1953, Schroder the upper parts of the non-marine Hills- 1963, McCutcheon 1978), and where such borough Member. Nevertheless, this still MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 17 does not preclude inclusion of both the tional zones (Norman 1932, Henderson Weldon and Hillsborough members as an 1940). Driller sands I and II, the upper- integral part of the Horton Group. most in the sequence, produce only small Although locally an unconformity exists quantities of oil and natural gas and, in between the Weldon and Hillsborough the Stoney Creek field, are laterally dis- members (cf. Schroder 1963), in most continuous, passing transitionally into areas they are apparently in conform- bituminous and calcareous shale, lime- able contact. In these latter areas, where stone and salt (Howie 1968). Driller sands the lithofacies are similar, it is extremely III and IV are the major gas producers. difficult and often impossible to allocate Driller sand V is the most persistent and specific outcrops and/or sections to one thickest bituminous shale (actually a dolo- or the other member. In such a case, the mitic marlstone) which, however, yields only real differentiating criterion is that little free-flowing oil, while the upper in general, the Weldon Member, when part of driller sand VI is the major oil considered in total, is finer grained than producer. the Hillsborough Member. Nevertheless, In the Stoney Creek field, the Albert because both members contain similar Formation is represented by a strati- lithofacies, and facies relationships are graphic section in the order of between varied and complex, the term Moncton c. 1350 and 1650m (Howie 1979), the upper Formation is perhaps the best descriptor, 670m of which are strata overlying dril- particularly where outcrop is sparse and, ler sand I consisting of thinly interbedded or, discontinuous. sandstones, siltstones and shales (some ALBERT FORMATION of which are more or less calcareous) and dolomites (Howie 1979). The remaining Four stratigraphic nomenclatural 680-980m (driller sands I-VI) consist of schemes have, to date, been proposed to shales, siltstones, sandstones, minor con- describe the internal stratigraphy of the glomerates and minor and thinly bedded Albert Formation, which has been inter- limestones. The sandstones are arranged preted as a composite alluvial fan, flu- in "packages" that in thickness range up vial-deltaic and lacustrine sequence (e.g. to 35m (Howie 1979, Pickerill and Carter Greiner 1962, Pickerill and Carter 1980, 1980). The number of sandstones per St. Peter 1982). The first proposed scheme "package" varies from well to well, a was based on the "driller sands" recog- maximum of 30 having thus far been re- nized by geologists of the New Brunswick corded (Howie 1979). These sandstone Gas and Oilfields Limited at the Stoney "packages" form the driller sand groups Creek field (Norman 1932); the second and are separated by 15-130m of non- was based on examination of the Albert bituminous or bituminous shales and silt- Formation in the entire Moncton Subbasin stones that in some areas appear to (Greiner 1962), which was in fact based merge laterally into thin sandstones. on the earlier work by Wright (1922); the 2. The second stratigraphic nomencla- third was based on a modification of the tural scheme was proposed by Greiner driller sand terminology and described by (1962), who subdivided the Albert Forma- Worth (1977); and the fourth was a modi- tion into three members based on the fication of Greiner's subdivision by three zones described originally by Wright Macauley and Ball (1982) and Macauley (1922). Greiner (1962) noted that in the et al. (1984). Table 1 summarizes the driller sand terminology, only driller sand nomenclatural schemes previously applied V could be readily recognized outside the to the Albert Formation including the Stoney Creek and Dover fields. This modifications recommended herein. effective marker horizon he referred to I. The original "driller sand" termino- as the Frederick Brook Member the logy was based on the recognition of six stratotype of which is along Frederick oil- and gas-bearing zones, five of which Brook in the vicinity of Albert Mines are sandstones and one a bituminous (Fig. 3). Strata underlying the Frederick shale, separated by intervening or transi- Brook Member were referred to as the 18 Carter and Pickerill

Dawson Settlement Member and the over- porite unit of local occurrence"; however, lying strata the Hiram Brook Member. he also extended it "... to include argil- The stratotype of the Dawson Settlement laceous dolomites, and anhydrite and Member was designated by Greiner (1962) gypsiferous beds of obvious evaporitic as New Brunswick Gas and Oilfields origin". This was based on and expanded Limited, Well Number 166 between 1200 the work of Gussow (1953). In later work, and 1557.9m, Albert County and the Greiner (1974, 1977) referred to the Gau- Hiram Brook Member as New Brunswick treau "Formation" as part of the Albert Gas and Oilfields Limited, Well Number Formation and occurring in "Albert time". 104 between 362.7m and 985.8m, Albert Recent workers have either chosen to County. The upper boundary of the Hiram ignore the problem entirely (e.g. Webb Brook Member was marked by conform- 1977) or have informally treated the Gau- able contact with either the overlying treau evaporites as a member of the Weldon Formation or Gautreau evaporites. Albert Formation (e.g. Hamilton 1961, The stratigraphic rank of the Gautreau Pickerill and Carter 1980, Macauley and evaporities has proved to be somewhat Ball 1982, Macauley et al. 1984). As the of an enigma particularly as no strato- member status of this laterally discontin- type was ever defined. Norman (1932) uous package of evaporites and associated formally proposed the Gautreau "Forma- sediments has become more commonly tion" as "... salt tongue in the upper recognized we herein formally propose Albert Formation." Greiner (1962) accept- that the package be referred to as the ed the formational status of the "... eva- Gautreau Member. Although no strato-

NORTH SOUTH

Q. 3

Pre-Carboniferous Basement

Fig. 4 - Schematic representation of the internal stratigraphy of the Horton Group, Moncton Subbasin, southern New Brunswick. MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 19

type was formally designated, two wells, member is equivalent to driller sand VI. which between them provide almost a In contrast to the Hiram Brook Member, complete section, may be considered as bituminous zones and argillaceous lime- the principal reference section. These are stones are rare or absent in the Dawson New Brunswick Gas and .Oilfields Limited, Settlement Member. Otherwise, the dis- Well Number 112 between 360.6 and tinction between lithotypes of the Hiram 937.8m and Well Number 49-1 from 387m Brook and Dawson Settlement members to the bottom of the hole at 750.3m, is difficult and their recognition relies Albert County. These cores are stored on the presence of the intervening, at the Mineral Resources Division, New readily recognizable, Frederick Brook Brunswick Department of Natural Member. Resources in Fredericton. As outlined previously, the upper con- The Hiram Brook Member consists of tact of the Hiram Brook Member is an heterogeneous assemblage of grey marked by transition into the overlying sandstone, siltstone and shale, the latter Weldon Member of the Moncton Forma- of which can be calcareous, bituminous tion, or, alternatively, into the Gautreau or both. It is bounded at the base by the Member. In the Weldon-Gautreau area, underlying Frederick Brook Member and, the Gautreau Member represents a small as noted above, at the top by the Gau- "salt basin" which probably developed treau Member and is c. 670m in thick- diachronously so that in part the member ness. In driller sand terminology it is is laterally equivalent to driller sands I equivalent to driller sands I (and even and II and elsewhere overlies driller sand higher, i.e. Gautreau Member) strati- I (see Howie 1968, fig. 7). A comparable graphically down through to the top of salt occurrence was documented by Worth V. Borehole data indicate that the mem- (1975) and Webb (1977) in the Cornhill ber exhibits considerable vertical and area, where a single drillhole intersected lateral facies variation even within a salt-bearing strata at a depth of c. 670m short geographic distance (Greiner 1962, within the Albert Formation, viz.: at an Howie 1968). approximately equivalent depth to that The Frederick Brook Member (equiva- of the Weldon-Gautreau deposit. Unfor- lent to driller sand V) consists of thinly tunately, the lateral extent of the Corn- laminated to papery, flexible, grey bitu- hill deposit is unknown. Nevertheless, it minous shale with minor interbeds of silt- may well represent another of several stone and thin argillaceous limestone. small restricted 'salt basins' which pass Upper and lower contacts are gradational laterally into coeval evaporitic and non- and are arbitrarily positioned where sand- evaporitic strata. stone/siltstone beds predominate or, 3. Worth (1977), informally proposed a alternatively, where the first shales low modification of the driller sand termino- in bitumen or lacking palaeoniscid fish logy for his report on the geology of the remains become prominent. Total thick- oil shales and lithofacies of the Albert ness is difficult to estimate but is usually Formation in the Hillsborough "Subbasin", quoted in the order of c. 180m (Greiner that is, that portion of the area of the 1962). A more detailed description of the Moncton Subbasin to the south of the types and relationships of lithologies may Westmorland Uplift. Essentially Worth's be obtained from King (1963) and classification applied only to this "sub- Pickerill and Carter (1980). basin" and was erected for working pur- The Dawson Settlement Member con- poses alone. For reasons outlined below, sists of an heterogeneous assemblage of the reader is referred to the report by sandstones, siltstones and shales with Worth (1977), the review by Carter and minor limestone interbeds near its top, Shaw (1979) and Table 1 for a more de- as exhibited in the stratotype (Greiner tailed consideration of this nomencla- 1962). Vertical and lateral facies vari- tural scheme. Further comment is deemed ations are quite complex and variably unnecessary because: developed. In driller sand terminology, the (i) The scheme was not designed to be 20 Carter and Pickerill applied outside the Stoney Creek and describe the development, both spatially Dover fields of the Hillsborough "Sub- and temporally, of grey-green fanglo- basin". merates that clearly interdigitate with (ii) Although the scheme was supposed- the three main members of the Albert ly a modification of driller sand termino- Formation (see for example Macauley logy, it is extremely difficult to relate et al. 1984, fig. 8). Herein we therefore the two. relegate the Round Hill to member status (iii) The scheme was based on the oc- within the Albert Formation, though do currence, according to Worth (1977), of accept that possibly in the future a new several diastems occurring within the stratotype will have to be defined. Albert Formation. Evidence for such dia- The primary focus of Macauley and co- stems was not presented and, further- workers was on the Frederick Brook more, in the absence of chronostrati- Member, which they informally subdivided graphic indicators or unconformities, can- into four lithologic units. In ascending or- not be realistically demonstrated. der they recognized a dolomite marl- 4. The most recent publications on the stone, a clay marlstone, an Albert Mines stratigraphic nomenclature of the Albert zone, and an upper unnamed unit (Table Formation were by Macauley and Ball 1). Recognition of this subdivision is dif- (1982) and Macauley et al. (1984), who: ficult and not applicable to field studies (i) accepted and based their scheme on since it is based primarily upon the dis- Greiner's (1962) threefold subdivision; tinction of the high grade oil shales of (ii) incorporated some of the more re- the Albert Mines zone or recognition of cent work, i.e. the complex temporal and the clay marlstone with its increased spatial facies relationships described by clay content and associated relatively Pickerill and Carter (1980) for the Albert high water content as indicated by Formation itself and the mapping and Fischer assay results. In fact Macauley stratigraphic relationships suggested by and Ball (1982, p. 75) state ... "In areas McLeod (1980) in the Hillsborough area, such as Albert Mines, recognition of the and Albert Mines zone is assured by the high (iii) reappraised previously unavailable kerogen content; however, such recogni- drill core which intersected the oil tion is not nearly so positive in areas shales. where environmental conditions were not Essentially, Macauley and Ball (1982) and favourable to the concentrated accumu- Macauley et al. (1984) incorporated the lation of algal material" (e.g. Boudreau, Round Hill "Formation" described by Dover, Rosevale and Urney). In the McLeod (1980) as a member of the Albert absence of the Albert Mines zone (e.g. Formation laterally equivalent to the due to nondeposition, poor exposure, etc.) three main members, viz: - the Hiram the zonation therefore hinges on the Brook, Frederick Brook and Dawson recognition of the clay marlstone by its Settlement members. As noted by Carter increased clay content and increased and Pickerill (1985) in their discussion of water yield determined by Fischer assay the results presented by Macauley et al. results. In short, this is not a particularly (1984), the Round Hill "Formation" of extremely useful zonation system for the McLeod (1980) should in fact be more field or well-site geologist. realistically recognized as a member of LITHOSTRATIGRAPHIC RELATIONSHIPS the Albert Formation. Recent mapping WITHIN THE HORTON GROUP in the type area by C. St. Peter (pers. comm. 1984) suggests that the originally Interpretation of stratigraphic relation- defined Round Hill Formation of McLeod ships within the Horton Group has been (1980) should, in fact, be more appropri- complicated by: aately referred to the Weldon Member (i)* Original complex depositional facies of the Moncton Formation. Nevertheless, variations, both in a temporal and spatial the descriptor Round Hill Member is still sense. regarded as useful and appropriate to (ii)* Post-depositional folding and fault- MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 21 ing, and, at least in some cases, syn- Equally as enigmatic are the strati- depositional, pre-Hillsborough Member graphic relationships within the Albert erosion. Formation itself. As previously noted by (iii) The paucity of continuously ex- Pickerill and Carter (1980), not only are posed sections. the Dawson Settlement and Hiram Brook (iv) The disregard of previous workers members in part temporally equivalent to the palaeoenvironmental framework in to, respectively, the Memramcook and which formational diachronism is the Moncton formations, but also member re- 'norm' rather than the 'noise' in the lationships within the Albert Formation system. itself are equally as complex (see Table (v) The absence of chronostratigraphic 1 and Fig. 4). The Round Hill Member, indicators. as previously noted, clearly interdigitates Table 1 is a schematic representation with the Hiram Brook, Frederick Brook of several of the previously outlined and Dawson Settlement members (see stratigraphic relationships. There is little Macauley et al. 1984, fig. 8) and is over- doubt that, apart from the Rosevale lain by the Weldon Member of the Monc- area, the Memramcook Formation is pres- ton Formation. Whereas Macauley and ent throughout the entire Moncton Sub- Ball (1982) and Macauley et al. (1984) basin and lies with marked unconformity included, in part, the Round Hill Member on pre-Carboniferous basement. Although as the (?) "sub-aqueous facies equivalent the Albert Formation is clearly underlain of the red conglomerates of the Mem- by the Memramcook Formation and over- ramcook and Moncton formations", we lain by the Weldon Member of the Monc- regard this as totally inappropriate. ton Formation, particularly in the central Firstly, this inclusion was not substanti- portions of the Moncton Subbasin, it is ated by these authors from either their also in part a lateral facies equivalent surface map interpretation or their drill to both (see McLeod and Ruitenberg 1978, data and secondly, and more importantly, Pickerill and Carter 1980). We suspect extending a member of the Albert For- that this situation is also complicated by mation across additional formational a possible structurally and sedimentologi- boundaries not only contravenes codes of cally conformable contact between dolo- stratigraphic nomenclature but also serves mitic shales (?Hiram Brook Member) of to compound an already complicated the Albert Formation and limestones and stratigraphic package (see Carter and evaporites of the Windsor Group, as Pickerill 1985). We therefore suggest that revealed by our recent examination of the Round Hill Member be strictly re- cores from the Upper Dorchester area garded as a member of the Albert For- (together with C. St. Peter and S.R. mation which, in the Hillsborough area McCutcheon). Thus it would appear that of the Moncton Subbasin, exhibits complex the Albert Formation and Windsor Group spatial and temporal development. To are in direct contact and the Moncton date, the relationship between the Round Formation did not develop in this parti- Hill and Gautreau members of the Albert cular area. As similar relationships have Formation are unknown. not been observed in surface outcrop, this Considering these relationships, it is occurrence requires further and more likely that in different portions of the detailed examination. Neverthelss, it does Moncton Subbasin, formation and mem- reflect the complex group and forma- ber contacts within the Horton Group, tional relationships developed within the and with the Windsor Group, can be Moncton Subbasin. gradational or one can be a lateral facies equivalent to the other. It is suggested *NOTE: Both (i) and (ii) above are that these lateral facies relationships are further complicated by the nature of the most common adjacent to the Caledonia poorly understood pre-depositional strike- Uplift, whereas in the more central por- slip and/or block faulting leading to basin tions of the Moncton Subbasin, the for- development and molding. mation contacts can be expected to be 22 Carter and Pickerill

more transitional, with one formation Brook and Gautreau members of the Al- clearly overlying the other (see Pickerill bert Formation are, in part, temporal and Carter 1980). This is not unusual in equivalents of, respectively, the Memram- the interpretation of strike-slip or pull- cook and Moncton formations. apart related basin structures or fluvial- The subdivision of the Frederick Brook lacustrine deposits described in other Member into four units by Macauley and areas (see for example Hardie et al. Ball (1982) and Macauley et al. (1984) is 1978, Eugster 1980, Bradley 1982, Farqu- regarded as useful but only in a limited harson 1982, Nickel 1982, Collinson 1983, context that certainly cannot be applied Eugster and Kelts 1983, Mann et al. 1983, to the subbasin as a whole. Hardie 1984, and others). As indicated in Table 1, the Albert Also, the concept of diachronism ap- Formation on the northern margin of the plied to comparable Carboniferous forma- Moncton Subbasin, from Millstream in tions in eastern Canada is by no means the southwest to Indian Mountain in the a new one. Hacquebard (1972, and refer- northeast, consists of the Hiram Brook ences therein), for example, demonstrated and Gautreau members (cf. Greiner 1962). formational diachronism between all In this area the medial Frederick Brook Visean-Westphalian strata in eastern Can- Member is not present to define the ada based on extensive collections of threefold subdivision of the Albert For- spore data. mation; nevertheless, the occurrence there of the Gautreau Member defines CONCLUSIONS the strata as 'upper' Albert Formation. It is also notable that Pickerill (1981) has The threefold subdivision of the Horton recorded in detail an extensive "algal a Group in the Moncton Subbasin into swamp" unit in the Millstream area pro- basal Memramcook Formation, a medial per which occupies a similar stratigraphic Albert Formation and an upper Moncton position to the Gautreau Member. This Formation conforms to the original des- unit consists of bituminous shales with cription and definition of the group by associated and extensive developments of Bell (1929) as well as to more recent diagenetic nodular carbonates and algal work in the Maritimes Basin (for review and oncolitic carbonates (see Pickerill see Knight 1983). In particular the Monc- 1981). The algal unit has not been exten- ton "Group" should be relegated to for- sively delineated because of its original mational status with previously established recognition in three closely spaced drill Weldon and Hillsborough "formations" as- holes (Gulf Minerals Canada Limited, suming member status (cf. Kelley 1967, LM8, 9 and 10 - see Pickerill 1981) and 1970; van de Poll 1972). The Moncton is merely regarded at this time as a Formation, although more properly facies variant within the Hiram Brook included within the Horton Group, is in Member. part laterally equivalent to the Windsor Group. ACKNOWLEDGEMENTS The threefold subdivision of the Albert Formation proposed by Greiner (1962) and Support for this work was provided based on the original work of Wright partially by the New Brunswick Depart- (1922) is regarded as the most applicable ment of Natural Resources and more fully to the subbasin as a whole, with the by the Natural Sciences and Engineering addition of the Round Hill member as a Research Council of Canada Grant A3857 spatial and temporal equivalent of all to R.K. Pickerill, both of which are three members in the Hillsborough to gratefully acknowledged. For their com- Sussex area, and the Gautreau Member prehensive reviews of the initial version (although to date not fully delineated of the manuscript we are grateful to Dr. spatially) being a temporal equivalent of A.G. Plint and Dr. M. Gibling. We also the Hiram Brook Member. The basal thank L. Fyffe, C. St. Peter, W. van de Dawson Settlement and the upper Hiram Poll, J.P. Anderle and S. McCutcheon for MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 23

active discussion particularly on the GUSSOW, W.C. 1953. Carboniferous Stratigraphy Albert Formation. Thanks are also ex- and Structural Geology of New Brunswick, tended to J.P. Anderle for permission to Canada. Bulletin of American Association of Petroleum Geologists 37, pp. 1713-1816. publish the geophysical data which was HACQUEBARD, P.A. 1972. The Carboniferous of compiled as a consulting report whilst Eastern Canada. In 7th Congress International the senior author was employed by J.P. de Stratigaphie et de Geologie du Carbonifere, Anderle Limited. The manuscript was Krefeld Comptes Rendus, Bd. 1, pp. 69-90. prepared by J. Ley and technical assis- HAMILTON, J.B. 1961. Salt in New Brunswick. Mineral Resources Report 1. Department of tance provided by S. Aitken and R. Mc Natural Resources, Mineral Resources Branch, Culloch in the preparation of line dia- Fredericton, New Brunswick, 73p. grams. HARDIE, L.A. 1984. Evaporites: Marine or Non- marine. American Journal of Science 284, pp. 193-240. ANDERLE, J.P., CROSBY, K.S. and WAUGH, HARDIE, L.A., SMOOT, J.P. and EUGSTER, H.P. D.C.E. 1979. Potash at Salt Springs, New Bruns- 1978. Saline lakes and their deposits: a sedimen- wick. Economic Geology 74, pp. 389-396. tological approach. In Modern and Ancient Lake BARSS, M.S., BUJAK, J.P. and WILLIAMS, G.L. Sediments. Edited by A. Matter and M.E. 1979. Palynological zonation and correlation of Tucker, Special Publication, International Associ- sixty-seven wells, eastern Canada. Geological ation of Sedimentologists 2, pp. 7-41. Survey of Canada, Paper 78-24, 103p. BELL, W.A. 1927. Outline of Carboniferous Strati- HENDERSON, J.A.L. 1940. The development of oil graphy and Geologic History of the Maritime and gas in New Brunswick. Canadian Institute Provinces of Canada. Royal Society of Canada, of Mining and Metallurgy Transactions 43, pp. Transaction Series 3, v. 21, pp. 75-108. 159-178. BELL, W.A. 1929. Outline of Carboniferous Strati- HOWIE, R.D. 1968. Stony Creek gas and oil field, graphy and Geologic History of the Maritime New Brunswick. American Association of Petro- Provinces of Canada. Royal Society of Canada, leum Geologists Memoir 9, v. 2, pp. 1819-1832. Transaction Series 3, v. 21, pp. 75-108. HOWIE, R.D. 1979. Carboniferous evaporites in BRADLEY, D.C. 1982. Subsidence in Late Paleozoic Atlantic Canada. Abstract, 9th International basins in the Northern Appalachians. Tectonics Congress on Carboniferous Stratigraphy and 1, pp. 107-123. Geology, University of Illinois, Urbana, Illinois, CARTER, D.C. and PICKERILL, R.K. 1985. A pp. 93-94. review of the Carboniferous Albert Formation KELLEY, D.G. 1967. Some aspects of Carboniferous Oil Shales, New Brunswick: Discussion. Bulletin stratigraphy and depositional history in the Canadian Petroleum Geology 33, (in press). Atlantic Provinces. Geological Association of CARTER, D.C. and SHAW, R. 1979. Albert Forma- Canada, Special Paper 4, pp. 213-228. tion Compilation. Department of Natural Re- KELLEY, D.G. 1970. Geology of Southeastern Can- sources, Mineral Resources Branch, Fredericton, ada: In Geology and Economic Minerals of Open File Report 79-33, 140p. Canada, Edited by R.J.W. Douglas. Economic COLLINSON, J.D. 1983. Sedimentology of uncon- Geology Report 1, pp. 229-366. formities within a fluvio-lacustrine sequence; KING, L.H. 1963. Origin of the Albert Mines Oil Middle Proterozoic of Eastern North Greenland. Shale (New Brunswick) and its Associated Alber- Sedimentary Geology 34, pp. 145-166. tite. Mines Branch Resource Report R115, De- EUGSTER, H.P. 1980. Geochemistry of evaporitic partment of Mines and Technical Surveys, lacustrine deposits. Annual Review Earth and Ottawa, 24p. Planetary Science 8, pp. 35-63. KNIGHT, I. 1983. Geology of the Carboniferous EUGSTER, H.P. and KELTS, K. 1983. Lacustrine Bay St. George Sub-basin, Western Newfound- chemical sediments. In Chemical Sediments and land. Newfoundland Department of Mines and Geomorphology. Edited by A.S. Goudie and K. Energy, Memoir 1, 358p. Pye. Academic Press, pp. 321-368. MACAULEY, G. and BALL, F.D. 1982. Oil Shales FARQUHARSON, G.W. 1982. Lacustrine deltas in of the Albert Formation, New Brunswick. New a Mesozoic alluvial sequence from Camp Hill, Brunswick Department of Natural Resources, Antarctica. Sedimentology 29, pp. 717-725. Mineral Development Branch, Open File 82-12, GREINER, H.R. 1962. Facies and sedimentary en- 173p. vironments of Albert shale, New Brunswick. MACAULEY, G., BALL, F.D. and POWELL, T.G. Bulletin of American Association of Petroleum 1984. A review of the Carboniferous Albert For- Geologists 46, pp. 219-234. mation Oil Shales, New Brunswick. Bulletin GREINER, H.R. 1974. The Albert Formation of New Canadian Petroleum Geology 32, pp. 27-37. Brunswick: a Paleozoic lacustrine model. Geo- MANN, P., HEMPTON, M.R., BRADLEY, D.C. and logische Rundschau 63, pp. 1102-1113. BURKE, K. 1983. Development of Pull-Apart GREINER, H.R. 1977. Crossopterygian fauna from Basins. Journal of Geology 91, pp. 529-554. the Albert Formation, New Brunswick, Canada, McCUTCHEON, S.R. 1978. Geology of the Apoha- and its stratigraphic-paleoecologic significance. qui-Markhamville Area. Map Area R-25 (21 H/ Journal of Paleontology 51, pp. 44-56. 11W, 21H/12E). Department of Natural Resources, 24 Carter and Pickerill

Mineral Resources Branch, Sussex, New Bruns- POPPER, G.H.P. 1965. Stratigraphic and tectonic wick, Map Report 78-5, 41p. history of the Memramcook terrestrial redbeds McCUTCHEON, S.R. 1981. Stratigraphy and paleo- of New Brunswick, Canada. Unpublished M.Sc. geography of the Windsor Group in Southern thesis, University of Massachusetts, Amherst, New Brunswick. New Brunswick Department of Massachusetts. Natural Resources, Mineral Resources Division SCHRODER, J.F. Jr. 1963. Stratigraphic and tec- open file 81-31. 210p. tonic history of the Moncton Group of non- McLEOD, M.J. 1980. Geology and mineral deposits marine redbeds of New Brunswick, Canada. Un- of the Hillsborough area, map area V-22, V-23. published M.Sc. thesis, University of Massachu- New Brunswick Department of Natural Resour- setts, Amherst, Massachusetts. ces, Mineral Development Branch, Sussex, N.B., ST. PETER, C. 1982. Geology of the Albert Forma- Map Report 79-6, 35p. tion, New Brunswick, Canada. 1982 Eastern Oil McLEOD, M.J. and RUITENBERG, A.A. 1978. Geo- Shale Symposium; Kentucky Department of logy and mineral deposits of the Dorchester Energy and University of Kentucky, Lexington, area, Map Area W-22, W-23 (21H/15E, 21H/16W). Kentucky, p. 39-47. New Brunswick Department of Natural Resour- van de POLL, H.W. 1972. Stratigraphy and economic ces, Mineral Development Branch, Sussex, New geology of Carboniferous basins in the Maritime Brunswick, Map Report 78-4, 27p. Provinces. 24th International Geological Con- NICKEL, E. 1982. Alluvial fan carbonate facies gress, Montreal 1972, Guidebook A60, 96p. with evaporites, Eocene Guarga Formation, WEBB, T.C. 1977. Geology of New Brunswick Glau- South Pyrenees, Spain. Sedimentology 29, pp. berite Deposits. New Brunswick Department of 761-796. Natural Resources, Mineral Resources Branch, NORMAN, G.W.H. 1932. Stratigraphy of the Stony Fredericton, Open File Report 77-15, 29p. Creek oil and gas field, New Brunswick. Geo- WILLIAMS, E.P. 1974. Geology and petroleum pos- logical Survey of Canada, Economic Geology sibilities in and around the Gulf of St. Lawrence Series 9, pp. 167-173. American Association of Petroleum Geologists NORMAN, G.W.H. 1941a. Moncton, Westmorland and Bulletin 58, pp. 1137-1155. Albert Counties, New Brunswick. Geological WORTH, J. 1975. Final report, Albert Formation, Survey of Canada, Map 646A with descriptive Oil Shale Mapping, Kings, Albert and Westmor- notes. land Counties, New Brunswick. Fundy Geoser- NORMAN, G.W.H. 1941b. Hillsborough, Albert and vices Limited, Reported for Canadian Occiden- Westmorland Counties, New Brunswick. Geo- tal Petroleum Limited. logical Suvey of Canada, Map 647A with des- WORTH, J. 1977. Oil shale and lithofacies, Albert criptive notes. Formation Hillsborough subbasin, New Bruns- PICKERILL, R.K. 1981. Paleoenvironmental inter- wick. Fundy Geoservices Limited. Report for pretation of Gulf Minerals Canada Limited Canadian Occidental Petroleum Limited. diamond drill holes, Millstream LM 8, 9 and WRIGHT, W.J. 1922. Geology of the Moncton Map 10; unpublished report for Gulf Minerals Canada Area. Canada Department of Mines, Memoir Limited, 33p. 129. PICKERILL, R.K. and CARTER, D.C. 1980. Sedi- mentary facies and depositional history of the Albert Formation. New Brunswick Department REVIEWERS: M. Gibling of Natural Resources, Open File Report 80-3, A.G. Plint 132p. PICKERILL, R.K., CARTER, D.C. and ST. PETER, C. 1985. Albert Formation - Oil Shales, Lakes, Fans and Deltas. Geological Association of Canada and Mineralogical Association of Can- ada, Fieldtrip Guidebook 6, Fredericton 1985, 77p.