Bullentin of Canadian Petroleum Geology最新文献

{"title":"Basin evolution in the Davis Strait area (west Greenland and conjugate east Baffin/Labrador passive margins) from thermostratigraphic and subsidence modelling of well data: implications for tectonic evolution and petroleum systems","authors":"E. McGregor, S. Nielsen, R. Stephenson","doi":"10.2113/GSCPGBULL.62.4.311","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.4.311","url":null,"abstract":"Abstract The sedimentary basins of the Davis Strait area developed mainly as a result of late Mesozoic and Cenozoic rifting processes that led to the formation of the West Greenland, southeast Baffin, and east Labrador continental margins. Recently acquired regional geophysical data in the area provide considerable new constraints on sedimentary basin and crustal thicknesses as well as plate kinematic reconstructions. Further, the chrono-stratigraphy and vitrinite reflectance data for several of the northern Labrador margin wells have been re-correlated and corrected. Given this, new 1-D models for the subsidence and thermal evolution of a number of the exploration wells located on the conjugate West Greenland and east Baffin/Labrador margins have been computed. Model predictions based on lithospheric extension agree well with observed stratigraphic and thermal data from West Greenland, southeast Baffin, and east Labrador wells. Calculated stretching factors for the wells are remarkably similar, except for those off southeast Baffin Island, which are higher. This implies that this area was subject to more intense rifting prior to the onset of magmatism in the early Paleocene. In turn, this may suggest that the magmatism was related to rifting and not, as commonly believed, linked to the arrival of a mantle plume at the beginning of the Paleocene. The modelled thermal histories indicate that maximum subsurface temperatures occurred at different times throughout the Cenozoic, depending mainly on the sedimentation (burial) histories, surface temperatures, and heat flow. Prediction of hydrocarbon generation in the area must therefore include these parameters.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.4.311","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New contributions in Baffin Bay/Labrador Sea petroleum exploration and development geoscience","authors":"J. Haggart","doi":"10.2113/GSCPGBULL.62.4.213","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.4.213","url":null,"abstract":"Baffin Bay and Labrador Sea encompass a vast marine region straddling the international jurisdictions of Canada and Greenland (Fig. 1). Together, these marine bodies encompass more than 1 500 000 km2 and they are bounded by a vast and geographically-complicated shoreline characterized by long fiords and deep channels. Sea-ice forms in much of Baffin Bay in winter, while icebergs originating from glaciers descending from the Greenland icecap create a constant hazard across the marine region during summer. Although much of the surrounding coastline is precipitous, a significant extent of continental shelf is present in these marine basins, characterized by accumulations of clastic strata, principally of late Mesozoic to Cenozoic age. Recent assessments of petroleum potential of the region have suggested that Baffin Bay may hold 1555 MMbbl of oil and 9.3 TCF of gas (Gautier et al., 2011), while shelf areas of the Labrador Sea may contain recoverable resources of 4.2 TCF of natural gas and 123 MMbbl of oil (Government of Newfoundland and Labrador, 2000).\u0000\u0000\u0000\u0000Figure 1 \u0000Map of Baffin Bay/Labrador Sea region showing principal geographic features and areas of focus of the contributions in the Special Issue. BI = Bylot Island; DI = Disko Island.\u0000\u0000\u0000\u0000While onshore exposures of Mesozoic-Cenozoic strata are extremely rare along the Labrador coast, significant onshore successions are found in the Baffin Bay region on Nuussuaq Peninsula and Disko Island and adjacent areas of West Greenland, and on Bylot Island and adjacent areas of northeast Nunavut. These successions provide accessible outcrops that serve as analogues for stratigraphic sequences preserved in the offshore. While extensive study of the Greenland succession has been undertaken recently, and a comprehensive litho- and biostratigraphic framework for these rocks established (Dam et al., 2009), similar studies of the Canadian side of the Baffin Bay are vintage 1970s. As well, some …","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.4.213","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The shallow stratigraphy and geohazards of the Northeast Baffin Shelf and Lancaster Sound","authors":"R. Bennett, D. C. Campbell, M. Furze","doi":"10.2113/GSCPGBULL.62.4.217","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.4.217","url":null,"abstract":"Abstract Hydrocarbon resource potential and a growing population have increased the need for new marine infrastructure in the Baffin Bay region. Before determining the viability of any seabed development, scientific understanding of geological hazards is essential. For this study, high resolution geophysical data and sediment samples on the Northeast Baffin Shelf and Lancaster Sound were analyzed to develop a shallow geological framework for the area and determine the distribution and severity of seabed hazards. The modern seafloor morphology and shallow stratigraphy are strongly influenced by past glacial processes. The Northeast Baffin Shelf consists of glacially eroded transverse troughs separated by flat-topped banks where glacial ice-contact and ice-proximal sediments rest on bedrock and are overlain discontinuously by postglacial sand or mud of various thickness. Lancaster Sound, which was occupied by glacial ice during the last glaciation, shares a similar shallow stratigraphy. Geohazards in the Baffin region differ from elsewhere on Canada's eastern continental margin. It is a seismically-active passive margin and its Arctic location means the area is more prone to the effects of iceberg scour and sea ice. Geohazards on the Baffin Shelf include hydrocarbon venting features, uneven seabed caused by glacial seabed features, seabed instability and sediment transport at trough margins, ice scour, and a high level of seismic activity.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.4.217","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary successions and palynoevent stratigraphy from the non-marine Lower Cretaceous to the marine Upper Cretaceous of the Nuussuaq Basin, West Greenland","authors":"G. Pedersen, H. Nøhr-Hansen","doi":"10.2113/GSCPGBULL.62.4.261","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.4.261","url":null,"abstract":"Abstract The Nuussuaq Basin, West Greenland, comprises the only exposures of Mesozoic sedimentary strata on the west coast of Greenland. The Nuussuaq Basin exposes Cretaceous and Paleocene siliciclastic strata, referred to as the Nuussuaq Group, overlain by volcanic rocks, mainly of Paleocene age, referred to as the West Greenland Basalt Group. Regional seismic studies indicate that the Cretaceous strata of the Nuussuaq Basin may be correlated to the Appat and Kangeq seismic sequences in the offshore basins. The present paper re-investigates five profiles, trending roughly east-west, from northern Disko to southern Svartenhuk Halvo, which exemplify the litho- and biostratigraphy, with a focus on the pre-Campanian deposits. The oldest exposed strata belong to the non-marine Kome Formation of possible Albian age. Dinoflagellate cysts that indicate brackish water conditions characterize the Albian and early Cenomanian, whereas marine dinoflagellate cysts occur in the latest Cenomanian, and in younger deposits. The dating of the Nuussuaq Group is based mostly on palynology, supported by scarce ammonites. A new, refined palynoevent stratigraphy is established, based on the study of many new and older sections. The new palynoevent stratigraphy allows a better correlation between widely spaced onshore sections and offshore successions, and provides an improved basis for paleogeographical interpretations.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.4.261","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance study of Paleocene and Cretaceous clastic sedimentary rocks from the Davis Strait and the Labrador Sea, based on U-Pb dating of detrital zircons","authors":"K. Thrane","doi":"10.2113/GSCPGBULL.62.4.330","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.4.330","url":null,"abstract":"Abstract Cretaceous–Paleocene strata of the Labrador Shelf and the Davis Strait are composed of clastic sedimentary and volcanic rocks, and some of these strata are considered possible petroleum reservoirs. The U-Pb provenance distributions of detrital zircons from nine different wells located in Davis Strait and on the Labrador Shelf, and which penetrate these rocks, were studied by LA-ICP-MS in order to assess sediment dispersal patterns and distribution of potential reservoirs. Samples from the mid-Cretaceous Bjarni Formation, the Upper Cretaceous Markland Formation, and the Paleocene Cartwright Formation were analysed. Based on U-Pb provenance data, the Bjarni Formation can be divided into northern and southern depositional areas. The northern area is dominated by 3000 Ma and 3200 Ma zircons, interpreted as derived primarily from the Hopedale block; in contrast, the southern area is dominated by 1800-1700 Ma ages, interpreted to be derived from the Makkovik Province and the Grenville Province. Markland Formation strata also show a variation in ages from north to south. Strata in the northern area are dominated by Archean zircons, with the main population at 3600–3500 Ma and significant numbers of 3800-3700 Ma and 2800-2700 Ma ages; in the southern area, no Eoarchean zircons were noted and strata are instead dominated by 3200-3100 Ma, 2900-2800 Ma, and 1800 Ma zircon populations. The Saglek block is interpreted as the dominant source for the northern area, mixed with sediment from the Hopedale block; the source for the southern area is inferred to be a combination of the Hopedale block and the Makkovik Province. Finally, the Cartwright Formation also shows distinct variations in source depending on the area. The northernmost samples yield a range of ages, and hence represent a large source area, with dominant zircon ages of 2800-2700 Ma. The middle area is dominated by a broad peak in ages from 3200-2550 Ma, whereas the southern area is dominated by Paleoproterozoic ages, with a large population at 1800 Ma. The general pattern for the Cartwright Formation is similar to that of the Bjarni and Markland formations in that the sediment transport direction was northerly and the main sources are interpreted to have been the Saglek block, Hopedale block, and the Makkovik Province. In addition, signatures from the Grenville Province, the Nain Plutonic Suite, and the Appalachian Orogen are also present. The detrital zircon patterns of the wells are consistent with Labrador as the main source region and the overall pattern indicates that the main sediment transport direction was generally northerly from Early Cretaceous until Paleocene time.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.4.330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Process ichnological analysis of the Lower Cretaceous Bluesky Formation, Alberta","authors":"Scott E. Botterill, S. G. Campbell, S. Pemberton, M. Gingras, Steve Hubbard","doi":"10.2113/GSCPGBULL.63.2.123","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.63.2.123","url":null,"abstract":"Abstract The process ichnological methodology was applied to a core dataset from the late Aptian to early Albian Bluesky Formation to identify the ichnological characteristics of ancient, marginal marine environments. This methodology has proven effective in recognizing the response of trace making organisms to various physico-chemical stresses in modern environments, but its application to ancient deposits is less established. Several previous studies of the Bluesky Formation have identified a wide range of depositional affinities; however few of these have focused on the detailed combination of ichnologic criteria outlined within the process ichnological framework. In order to assess the effectiveness of the process ichnological framework to the rock record, high resolution, systematic ichnological characteristics were recorded and combined with sedimentologic data from nine wells containing core from within the Bluesky Formation. These characteristics led to the identification of several inferred physico-chemical stresses within the dataset showing an overall evolution from high energy brackish water deposition to a low energy, marine setting. This study contributes to the well-established brackish-water ichnological model and, in addition, helps establish the utility of the process ichnological methodology in the recognition of physico-chemical stresses in ancient environments.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.63.2.123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68207668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discovery of organic-rich black shale xenolith from kimberlite on the Hall Peninsula, Nunavut and its implication for petroleum potential in Cumberland Sound","authors":"Shunxin Zhang, R. Creaser, J. Pell","doi":"10.2113/GSCPGBULL.62.3.125","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.3.125","url":null,"abstract":"The Chidliak kimberlite province covers an area of 40 × 70 km on the eastern Hall Peninsula, southeastern Baffin Island, Nunavut, between Frobisher Bay and the Cumberland Sound (Fig. 1). The eastern Hall Peninsula is an Archean gneissic terrain, into which all the Late Jurassic–Early Cretaceous aged kimberlites (156.7–139.1 Ma; Heaman et al., 2012) intruded. At present, there is no consolidated Phanerozoic sedimentary cover on the Hall Peninsula; however, a great number of sedimentary rock xenoliths yielding conodont microfossils were entrained by the kimberlites. These xenoliths suggest that Upper Ordovician and Lower Silurian strata with a total thickness about 270–305 m were present on the Hall Peninsula at least until Early Cretaceous time (Zhang and Pell, 2013; 2014).\u0000\u0000\u0000\u0000Figure 1 \u0000A). Simplified geologic map of the Foxe Basin and vicinity (modified from Wheeler et al., 1997), showing the location of the Chidliak project area (red polygon), the drill hole CHI-482-10-DD01 with the black shale xenolith (red star), suspect natural hydrocarbon seep (yellow dots; location data from Budkewitsch et al., 2013) and Paleozoic (black cross) and Mesozoic (red cross) cores collected by shallow drillings during 1970s and 1980s (location data from Zhang, 2013a). B). Enlargement of the area enclosed by black rectangle in (A).\u0000\u0000\u0000\u0000Cumberland Sound, to the northeast, is partially underlain by Cretaceous clastic and Paleozoic carbonate sedimentary rocks (Fig. 1; MacLean et al., 1986). On the sea surface of Cumberland Sound, 28 suspect natural hydrocarbon seep occurrences were identified (Fig. 1; Budkewitsch et al., 2013), indicating an active petroleum system may occur in the sound; however, the source rocks remain uncertain.\u0000\u0000A rare black shale xenolith (Fig. 2A) was discovered from a kimberlite on the Hall Peninsula. Given the geologic and geographic position of the peninsula, it provides valuable evidence about the possible existence of an active …","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.3.125","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An exceptional record of the sedimentology and biostratigraphy of the Montney and Doig formations in British Columbia","authors":"M. Golding, M. Orchard, J. Zonneveld, C. Henderson, L. Dunn","doi":"10.2113/GSCPGBULL.62.3.157","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.3.157","url":null,"abstract":"Abstract The Talisman Altares 16-17-083-25W6M well in British Columbia penetrates the entirety of the Triassic Montney Formation and possesses core coverage of most of it, including the basal contact with the underlying Permian Belloy Formation and its upper contact with the base of the Triassic Doig Formation. The Montney Formation in British Columbia is punctuated by several flooding surfaces and is bound top and bottom by two sequence boundaries: one at the Belloy-Montney formation boundary and one at the Montney-Doig boundary. These two surfaces can be correlated throughout wells in British Columbia and into Alberta. Conodont data from British Columbia shows that the lower-middle Montney boundary is Smithian in age, and the middle-upper Montney boundary approximates the Smithian-Spathian boundary. These age determinations are significantly younger than previous estimates for the equivalent boundaries in Alberta, underscoring the inherent diachroneity of lower Mesozoic lithostratigraphic subdivisions in Western Canada. The Montney-Doig boundary occurs within the Spathian in this well, and is therefore older here than in other wells in northeastern British Columbia. It is also older than previous estimates for the age of the boundary that have ranged from the Anisian to the Ladinian.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.3.157","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of differential chemical compaction in the formation of the Gold Creek Collapse Structure, West Central Alberta","authors":"K. Barrett","doi":"10.2113/GSCPGBULL.62.3.132","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.3.132","url":null,"abstract":"Abstract The Gold Creek Gas Field has produced in excess of 2.5 billion cubic meters (>90 Bcf) of gas plus natural gas liquids from the Upper Devonian Wabamun Formation. The Wabamun is a 220 m thick limestone that is only porous and productive where fault-controlled dolomite is present. These faults are associated with a significant episode of structural collapse that has resulted in up to 160 m of negative relief on the Wabamun structure. Compensatory thickening of the overlying Mississippian Formations accompanied subsidence. The mechanism of collapse is interpreted to be differential compaction within the underlying Devonian Leduc reef. In response to overburden pressure, the muddy lagoonal sediments of the Leduc reef interior are interpreted to have undergone a higher degree of stylolitization than the coarser grained reef margin. Differential compaction commenced at the onset of Mississippian deposition and reached its zenith during Debolt Formation deposition. During the early stages of this process, the Leduc reef had been a closed diagenetic system that limited the magnitude of differential compaction. Debolt age rapid subsidence induced faulting that extended upwards from the Leduc through to the Debolt Formation. It is interpreted that CaCO3 saturated fluids were expelled from the Leduc reef and flowed upwards along the faults through the overlying Mississippian sediments and presumably to the surface. This permitted chemical compaction to proceed within the reef at a greatly accelerated rate leading to reef collapse. A second, more modest period of collapse occurred slightly later during Stoddart Group deposition. Seismic data along with isopach and structural mapping were used to quantify the amount of compensatory thickening that occurred and to establish the chronology of associated faulting. The Gold Creek Collapse Structure formed in three stages during the Mississippian Period. The first stage occurred during deposition of the Exshaw to Shunda Formation interval. The second stage occurred during Debolt Formation deposition and the remaining subsidence occurred during Stoddart Group deposition. Depth of burial of the Gold Creek Leduc Reef increased from 335 m to 743 m during stage one. During stages two and three the depth of burial increased to 992 m and 1035 m, respectively.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.3.132","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Allostratigraphy and paleogeography of the Harmon and Cadotte members of the Peace River Formation (Middle Albian), west-central Alberta and adjacent British Columbia","authors":"Olivia A. Henderson, K. Vannelli, A. Plint","doi":"10.2113/GSCPGBULL.62.3.177","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.62.3.177","url":null,"abstract":"Abstract The mudstone-dominated Harmon and sandstone-dominated Cadotte members of the Peace River Formation were deposited during the middle Albian in the southern end of a Boreal marine embayment that occupied the foredeep of the Western Canada Foreland Basin. Sandstone of the Cadotte Member represents a shoreface environment and has traditionally been interpreted as the updip equivalent of offshore Harmon mudstone. Allostratigraphic correlation, based on marine flooding surfaces and unconformities shows that the Harmon alloformation can be divided into five regionally-mappable allomembers. Similar erosion surfaces allow the Cadotte alloformation to be divided into three allomembers. The new allostratigraphy shows that the informal Harmon and Cadotte alloformations do not have an interfingering relationship and hence are not genetically related. Harmon and Cadotte allomembers have been mapped over about 100 000 km2, but show no evidence of stratal lap-out or depositional topography; it is concluded that deposition took place on a shallow marine ramp of very low relief. The vertical stacking of Harmon and Cadotte allomembers across the foredeep indicates that rates of accommodation and sediment supply remained in approximate equilibrium throughout deposition of these units. In the far southern and eastern parts of the study area, changing gamma ray log response suggests that marine deposits of both the Harmon and Cadotte alloformations grade laterally into coeval coastal plain deposits that are mapped in outcrop as Gates Formation whereas in subsurface wireline log picks, these rocks are usually included in the Upper Mannville Group. The lateral boundary between offshore mudstone and coeval nearshore muddy sandstone can be mapped within individual Harmon allomembers; the mudstone to sandstone boundary has a lobate to cuspate pattern in plan view, suggesting that, at the southern extremity of the ‘Harmon Sea’ rivers built elongate deltas in a very shallow-water, low wave-energy setting. Lenticular, sharp-based sandstone bodies 17–42 m thick hang from allomember bounding surfaces in both the Harmon and Cadotte alloformations; these sandbodies probably represent paleovalley fills. Valley incision may have been linked to relative sea-level changes that also gave rise to the marine transgressive surfaces that are traceable over the entire study area. In the east, both the Cadotte and Harmon alloformations are completely truncated by a bevelling unconformity at the base of the Paddy and the laterally-contiguous Joli Fou alloformation.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.62.3.177","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68206657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}