Moose Mountain Research Articles

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20th century

AbstractClimate‐induced variation in lake level can affect physicochemical properties of endorheic lakes, but its consequences for phototrophic production and regime shifts are not well understood. Here, we quantified changes in the abundance and community composition of phototrophs in Kenosee and White Bear lakes, two endorheic basins in the parkland Moose Mountain uplands of southeastern Saskatchewan, Canada, which have experienced > 8 m declines in water level since ~ 1900. We hypothesized that lower water levels and warmer temperatures should manifest as increased abundance of phytoplankton, particularly cyanobacteria, and possibly trigger a regime shift to turbid conditions due to evaporative concentration of nutrients and solutes. High‐resolution analysis of sedimentary pigments revealed an increase in total phototrophic abundance (as β‐carotene) concurrent with lake‐level decline beginning ~ 1930, but demonstrated little directional change in cyanobacteria. Instead, significant increases in obligately anaerobic purple sulfur bacteria (as okenone) occurred in both lakes during ~ 1930–1950, coeval with alterations to light environments and declines in lake level. The presence of okenone suggests that climate‐induced increases in solute concentrations may have favored the formation of novel bacterial habitats where photic and anoxic zones overlapped. Generalized additive models showed that establishment of this unique habitat was likely preceded by increased temporal variance of sulfur bacteria, but not phytoplankton or cyanobacteria, suggesting that this abrupt change to physical lake structure was unique to deep‐water environments. Such climate‐induced shifts may become more frequent in the region due to hydrological stress on lake levels due to warming temperatures across the Northern Great Plains.

Trochodendraceous Fruits and Foliage in the Miocene of Western North America

Two fossil fruit types and at least one fossil leaf type representing Trochodendraceae are recognized from the middle Miocene Cascadia flora of western Oregon, USA. Trochodendron rosayi sp. nov., known also from the middle Miocene of eastern Oregon and northern Idaho, is based on long-pedicelled, apically dehiscent capsular fruits with 7-9 persistent outcurved styles, very similar to the extant monotypic east Asian species T. aralioides. Concavistylon kvacekii gen. et sp. nov. is named for a racemose infructescence bearing shortly pedicellate, apically dehiscent capsules with 4 to 5 persistent incurved styles arising from the basal 1/3 of the fruit. Leaves associated at the Moose Mountain locality are recognized as Trochodendron postnastae sp. nov. They have basally acrodromous venation with a prominent midvein bracketed by a pair of strongly ascending basal secondaries and are thought to correspond to the T. rosayi fruits. These new occurrences demonstrate that greater diversity was present among fossil Trochodendraceae than previously recognized during the Miocene in western North America.

Imagery Integration Methods for Precise Geological Mapping of Rugged Terrain, Alberta, Canada

This paper reports on new geological mapping techniques using the rugged area of Moose Mountain, Alberta as a test site. First, we present a web-accessible photographic database that facilitates interactive visualization of multiple rock exposures for geology mapping, and second, the results of analysis of two readily available oblique photogrammetric methods, that have been previously applied to archeological and industrial surveys. These two techniques of high-resolution terrestrial oblique photogrammetry called block bundle and were tested using the web database, in order to evaluate their precision and accuracy as mapping techniques. The efficiency of the new techniques to support geological mapping is compared to other mapping techniques. The results show that in conditions where high-resolution digital elevation and imagery data are available, a web-based terrain rendering technique, combined with a web-accessible photographic database of rock exposures is advantageous to a wide range of geological analyses, including analog modeling of hydrocarbon reservoirs.

Regional Variation in <em>Amelanchier</em> in the Whitewood area of Southeastern Saskatchewan and the First Saskatchewan Records of <em>Amelanchier sanguinea</em>

Based on measurements and evaluation of 111 specimens from 51 localities in the Whitewood area of southeastern Saskatchewan, most Amelanchier alnifolia from the prairie parkland is represented by short, stoloniferous shrubs, less than 2 m tall with 5 – 100+ stems. In the Moose Mountain area, A. alnifolia is represented by shrubs that are taller, sometimes to 7 m, not stoloniferous and usually having fewer than five stems. Although many of these plants have the inflorescence characteristics of A. alnifolia, some are referable to the eastern A. sanguinea, not previously reported from southeastern Saskatchewan. Such plants appear to be confined to the wooded environment of Moose Mountain. Amelanchier alnifolia is not as clearly differentiated by habit or leaf tip characteristics as the literature suggests. Inflorescence characteristics, habit and actual genetic variation may be associated with biogeographic patterns, especially historically wooded islands within the prairie ecozone. These patterns are an important consideration in classification studies and in protecting and utilizing Amelanchier germplasm.

USING ISOTOPIC VARIANCE TO DETECT LONG-DISTANCE DISPERSAL AND PHILOPATRY IN BIRDS: AN EXAMPLE WITH OVENBIRDS AND AMERICAN REDSTARTS

Abstract Understanding movements of individual birds between breeding sites (breeding dispersal) or between natal sites and the site of first breeding (natal dispersal) is crucial to the modeling of population dynamics. Unfortunately, these aspects of demography are poorly understood for avian species in general, and for migratory songbirds in particular. This is because it is often impossible to sample broadly enough to relocate marked birds that have moved. We used stable-hydrogen (δD) and carbon (δ13C) isotope analyses of the feathers of 139 American Redstarts (Setophaga ruticilla) and 193 Ovenbirds (Seiurus aurocapillus) to evaluate evidence for individuals molting feathers at locations other than their breeding sites from the previous year. We sampled outer rectrices from breeding populations at three extensive boreal forest sites (Prince Albert National Park and Duck Mountain, Saskatchewan, and Lac La Biche, Alberta) and at three isolated forest tracts (Cypress Hills, and Moose Mountain, Saskatchewa...

Integration of photogrammetric data in the construction of a 3-D geological model in a thrust-fold belt, Moose Mountain, Alberta, Canada

Integration of photogrammetric data in the construction of a 3-D geological model in a thrust-fold belt, Moose Mountain, Alberta, Canada

Mesoproterozoic reactivation of a Paleoproterozoic transcurrent boundary in the northern Colorado Front Range: Implications for 1.7- and 1.4-Ga tectonism

Proterozoic metamorphic and igneous rocks in the northern Colorado Front Range display evidence for significant but localized 1.4-Ga deformation. Initial metamorphism and deformation occurred during crustal assembly ∼1.7 Ga, and the area was subsequently affected by widespread “anorogenic” granitic plutonism at ∼1.4 Ga. Although there is little evidence for penetrative 1.4-Ga deformation in northern Colorado, data from the northeast-striking Moose Mountain shear zone indicate localized 1.4-Ga contractional strain. The shear zone deforms both pre-1.70-Ga supracrustal rocks and the ∼1.4-Ga St. Vrain granite. Kinematic indicators within the deformed granite show south-side-up reverse motion. A continuum from magmatic to solid-state mylonitic fabrics indicates that deformation occurred during the emplacement and cooling of the granite at ∼1.4 Ga. Thrust-sense deformation, coupled with synchronous northeast-southwest extension recorded in dike swarms, is consistent with a model for regional northwest-directed contractional deformation during emplacement of the 1.4-Ga plutonic suite. Paleoproterozoic supracrustal rocks within the shear zone show evidence for the 1.4-Ga shearing as well as for an older phase of deformation apparently dominated by sinistral motion. Supracrustal rocks on opposite sides of the shear zone record different structural histories, and detrital zircon samples differ dramatically in age populations across the shear zone. These data lead us to suggest that the shear zone separates two unrelated packages of rocks that were juxtaposed against one another during ∼1.7-Ga assembly of the region. Thus, original assembly of this region around 1.7 Ga probably involved previously undocumented transcurrent movements that juxtaposed “terranes” with differing Paleoproterozoic histories and resulted in large-scale zones of crustal weakness that localized subsequent deformation.

Implications of meso-structures for deformational history of the Moose Mountain structure, Canadian Rocky Mountain foothills

We use small-scale structures (meso-structures) to investigate strain and to interpret the deformation history of the Moose Mountain structure in the southern Canadian Rocky Mountains. Small-scale structures measured at seven sites encompass 440 measurements of fault planes with striations, veins and fold axes. Kinematic analysis suggests that these meso-structures record three different shortening directions that changed during the evolution of the Moose Mountain structure from NE–SW–ENE–WSW, to E–W and subsequently to NNE–SSW. NE–SW–ENE–WSW shortening is compatible with the large-scale geometry of the Moose Mountain structure and with thrust-fault orientation in the study region, whereas the relationship with E–W and NNE–SSW shortening is less obvious. Small-scale reverse faults and part of the veins are interpreted as forming during early deformation in association with the development of the macro-scale thrust faults of the Rocky Mountains, whereas the mesoscopic strike-slip faults, veins and micro-folds developed later. A relatively large number of the strike-slip faults and veins are interpreted to have been generated by reactivation of pre-existing structures. This study demonstrates again that small-scale structures can discriminate modifications in regional strain directions and identify moderate episodes of deformation within deformed terrains such as the Foothills thrust-belt.

Reconstruction of glacial Lake Hind in southwestern Manitoba, Canada

Glacial Lake Hind was a 4000 km2 ice-marginal lake which formed in southwestern Manitoba during the last deglaciation. It received meltwater from western Manitoba, Saskatchewan, and North Dakota via at least 10 channels, and discharged into glacial Lake Agassiz through the Pembina Spillway. During the early stage of deglaciation in southwestern Manitoba, part of the glacial Lake Hind basin was occupied by glacial Lake Souris which extended into the area from North Dakota. Sediments in the Lake Hind basin consist of deltaic gravels, lacustrine sand, and clayey silt. Much of the uppermost lacustrine sand in the central part of the basin has been reworked into aeolian dunes. No beaches have been recognized in the basin. Around the margins, clayey silt occurs up to a modern elevation of 457 m, and fluvio-deltaic gravels occur at 434–462 m. There are a total of 12 deltas, which can be divided into 3 groups based on elevation of their surfaces: (1) above 450 m along the eastern edge of the basin and in the narrow southern end; (2) between 450 and 442 m at the western edge of the basin; and (3) below 442 m. The earliest stage of glacial Lake Hind began shortly after 12 ka, as a small lake formed between the Souris and Red River lobes in southwestern Manitoba. Two deltas at an elevation of 450 were formed in this lake. At the same time, the Souris Lobe retreated far enough to allow glacial Lake Souris to expand farther north along the western side of the basin from North Dakota into what was to become glacial Lake Hind. Three deltas were built at an elevation above 460 m in the Canadian part of this proglacial lake. Continued ice retreat allowed the merger of glacial Lake Souris with the interlobate glacial Lake Hind to the east. Subsequent erosion of the outlet to the Pembina Spillway allowed waters in the glacial Lake Hind basin to become isolated from glacial Lake Souris, and a new level of glacial Lake Hind was established at 442 m, with 5 deltas built at this level by meltwater runoff from the west. Next, a catastrophic flood from the Moose Mountain uplands in southeastern Saskatchewan flowed through the Souris River valley to glacial Lake Souris, spilling into Lake Hind and depositing another delta. This resulted in further incision of the outlet (Pembina Spillway). A second flood through the Souris Spillway from glacial Lake Regina further eroded the outlet; most of glacial Lake Hind was drained at this time except for the deeper northern part. Coarse gravel was deposited by this flood, which differs from previous flood gravel because it is massive and contains less shale.

Heard but Not Necessarily Seen: Surveys of Birds at Greenwater and Moose Mountain Provincial Parks

Heard but Not Necessarily Seen: Surveys of Birds at Greenwater and Moose Mountain Provincial Parks

Effects of beech bark disease on the growth of American beech (Fagusgrandifolia)

We studied radial growth reduction in American beech (Fagusgrandifolia Ehrh.) in relation to the level of defect induced by beech bark disease, in second-growth and old-growth northern hardwoods stands in New Hampshire. In the second-growth stand at Moose Mountain (n = 243 trees), 1989–1990 radial growth declined significantly with increasing severity of external symptoms. The severity of external symptoms increased significantly with DBH. To examine temporal trends, internal defect induced by the disease was quantified as the percentage of growth sheath cankered in each year, by cross-sectioning a subsample of 40 trees. Internal defect first appeared in 1950, increased through 1969, then declined until a major pulse of infection in the period 1983–1987. Sectioned trees were divided into infection classes based on a cumulative measure of internal defect. Growth of severely infected trees first fell below that of uninfected trees in 1965, and was consistently lower after 1972. The growth ratio of severely infected to uninfected trees generally declined from 1960 to 1990; by 1990, growth of severely infected trees was reduced by more than 40% relative to healthy trees. This decline in the growth ratio corresponded well to the increase in cumulative internal defect in the stand, suggesting that disease stress had cumulative effects on tree vigor. The relation between beech bark disease and growth was also examined on an individual-tree basis; recent growth decline was significantly greater for trees with higher levels of internal defect. Internal defect was a better predictor of growth trends than was external defect. External defect was only moderately correlated with internal defect (r2 = 0.503). In the old-growth stand at Bartlett, N.H. (n = 40 trees) infection was quantified from external symptoms only. As in the second-growth stand, the growth of severely infected trees in the old-growth stand fell significantly below that of uninfected trees. However, significant differences in growth between uninfected and severely infected trees occurred earlier in the old-growth stand, first appearing in 1949. Delayed growth reductions in the second-growth stand may be associated with changes in shade and moisture affecting the beech scale, changes in tree physiological stress after selective logging, or changes in the density of large trees. Beech may survive long periods of infection by beech bark disease. However, our results demonstrate clearly that beech bark disease has reduced the growth of American beech in both second-growth and old-growth northern hardwoods stands for several decades.

Sedimentology and paleohydrology of glacial-lake outburst deposits in southeastern Saskatchewan and northwestern North Dakota

Glacial-lake outbursts occurred in the northern Great Plains as ice-marginal lakes suddenly drained, forming an interconnected system of glacial-lake spillways. The outbursts were highly erosive, and consequently, deposits from such discharges are rare in the spillways. Glacial-lake–outburst deposits in the Souris, Des Lacs, and Moose Mountain spillways, Saskatchewan and North Dakota, have distinct bar shapes and, internally, are more massive and homogeneous than those of outwash systems. In this paper, the outburst deposits are described, and the sedimentologic and hydrodynamic characteristics of the outburst discharges are interpreted. Coarse-grained sediment eroded from till formed large-scale bars in the spillways, as much as 2 km long and 30 m thick, both as pendant bars and bars in alcoves next to contemporaneous landslides. Internally, the bars consist of homogeneous masses of massive, matrix-supported, very poorly sorted, pebbly cobble gravel, containing boulders as much as 3 m in diameter. The maximum particle sizes in individual bars decrease downstream and toward spillway sides. The lithology of the bars resembles the local glacial drift; material from the Tertiary bedrock, in which the spillways are partially incised, is not concentrated in the bars. Paleohydraulic calculations based on data of maximum particle size and on the Shields9 entrainment function yield unreasonably large values. Supplementary calculations based on depth limits established from field observations yield realistic values; this method indicates that velocities of 2.9 to 11.7 ms −1 and discharges of 5.8 × 10 4 to 8.2 × 10 5 m 3 s −1 were achieved by the outburst. Sediment-water concentrations during the outburst, estimated by dividing the volume of sediment eroded by the source-lake volume, averaged ∼20% by weight. Because of this estimate, the abundant amount of fine-grained material that was eroded, and structure of the outburst deposits, we infer that outburst flows were hyperconcentrated, with sediment-water concentrations being as much as ∼40% by weight in some areas. We further infer that sediment transport was extremely efficient and that most particles, including coarse gravel, were transported in suspension. This interpretation is consistent with the sedimentology of the deposits and other conjectural evidence. Expanding sections caused coarser sediment to be deposited, indiscriminate of clast size, as poorly sorted, massive gravel bars. Finer grained sediment, sand to clay size, was transported through the spillway system into downstream glacial lakes.

Structural Geology of Stewart Peak Culmination, Idaho-Wyoming Thrust Belt

A structural culmination is the highest point along a structural axis or fold system, away from which the folds plunge. Structural culminations are an important and predictable component of foreland fold-thrust belts, and are prime targets for oil and gas accumulations. The Stewart Peak culmination is a doubly plunging anticlinorium in the Absaroka thrust sheet of western Wyoming, located in the northern Salt River Range. Major thrust faults in the Stewart Peak culmination comprise a large-scale duplex zone. The roof fault of the duplex is the Absaroka thrust, the floor fault is the basal or regional decollement, and the intervening Murphy and Firetrail thrusts are trailing-edge imbricate faults in the Darby plate that have locally uplifted and deformed the Absaroka into an asymmetric, breached anticlinorium or culmination. In addition, these major thrust faults subdivide the culmination into fault-bound structural horses, each with a characteristic style of deformation as a function of its stratigraphic and structural level in the duplex. A recent exploratory test of the culmination provided data which suggest that the Absaroka thrust locally cuts downsection in the transport direction. This may be explained by initial folding and breaching of the Firetrail anticline, followed by main motion on the Absaroka thrust which overrode the fold. The available data suggest that the Stewart Peak culmination is the result of (1) polyphase uplift or arching of the Absaroka thrust sheet by the Murphy and Firetrail thrust sheets, (2) lateral imbrication and ramping, and (3) arching of the Precambrian basement complex beneath the northern Salt River Range. In addition, a basic kinematic model of deformation applicable to structural culminations includes emplacement of an allochthonous mass over a parautochthonous substratum, closely followed by, or contemporaneous with, deformation and translation of the footwall section to produce a duplex zone that folds the overlying allochthon. The Stewart Peak culmination bears many similarities in structural style and origin to polyphase folded-fault domes in the Canadian Rocky Mountains. Specifically, the Stewart Peak area is compared to the Savanna Creek and Moose Mountain culminations.

Mississippian Conodonts from Well Cores, Crossfield, Alberta: ABSTRACT

Cores from three wells drilled into the Elkton Member of the Turner Valley Formation at Crossfield, Alberta, yielded numerous conodonts. These conodonts permit interregional and intraregional correlation to other sections in western Canada, to strata in the upper Mississippian Valley region, and to sections in Europe. This material came from 300 to 500 g samples taken at 5 ft (1.52 m) intervals from 0.5 in (1.26 cm) slabs of well cores. Eotaphrus burlingtonensis and Polygnathus mehli are common and allow recognition of the Eotaphrus Subzone of the Eotaphrus-Bactrognathus Zone. This subzone can be recognized within the Turner Valley Formation at Cadomin and Moose Mountain and the lower Livingstone Formation in Bow Valley sections. This subzone also occurs in the upper part of the Burlington Formation within the type region of the Mississippian System and in the upper Tournaisian (Tn3c) of Belgium, Britain, and Germany. End_of_Article - Last_Page 546------------

Hydrocarbon Accumulations in Overthrust Belt of Alberta: ABSTRACT

Estimated proved and probable ultimate reserves of marketable natural gas in Alberta are 80.5 tcf, of which approximately 10.5 tcf are in Paleozoic carbonate reservoirs that have been involved in thrust faulting in the Foothills belt of Alberta. Interpretation of exploration data in this belt has contributed significantly to our understanding of the geology of the southern Canadian Rocky Mountains as a whole. The Precambrian basement is overlain by a westward-thickening prism of Paleozoic sedimentary deposits that contain important reservoirs in Upper Devonian and Mississippian carbonate rocks. Approximately 8% of the reserves are in the Upper Devonian and 87% in the Mississippian. There is close correlation between reserves found and facies trends within the Mississippian Rundle Group. A widespread organic-rich source rock, the Exshaw Formation, provided the major charge for both Mississippian and Devonian reservoirs. Jurassic marine shales overlie the Mississippian in the southern part of the belt and form an effective seal and possible source rock. In the northern part of the belt, the Mississippian is overlain by Triassic sedimentary rocks in which reservoirs are present. Cretaceous sa dstones generally lack reservoir qualities and less than 5% of the reserves found to date are in the Cretaceous. The Outer Foothills are characterized by closely spaced listric thrust faults that repeat the Mesozoic section. Some of the thrusts cut deep enough to carry a single or multiple thrust slices End_Page 573------------------------------ of Mississippian carbonate rocks. Trap capacity is governed by horizontal displacement, vertical uplift, convergences of allochthonous and autochthonous structural strike, and probable seal quality to the thrust planes. Approximately 18 significant gas-bearing structures containing 5 tcf marketable reserves have been discovered. The surface geology of the Inner Foothills is characterized by outcrops of Paleozoic carbonate rocks and relatively undeformed Mesozoic strata. Usually two or more thrust sheets are stacked in a general anticlinal form and provide multiple objectives. To date, 14 gas-bearing structures have been discovered in this zone containing approximately 5.5 tcf of gas. The gas-bearing structures in the Waterton-Carbondale and Moose Mountain Panther River areas are typical. The gas-bearing post-lower Paleocene structures probably are related to the time of maturation of the major source rock and the west-to-east deformation of the southern Canadian Rocky Mountains. Despite the large areas of the Alberta Foothills belt in which exploration is restricted, it is estimated that 6 to 14 tcf of gas ma still be found. End_of_Article - Last_Page 574------------

The Morrissey and Mist Mountain Formations -- Newly Defined Lithostratigraphic Units of the Jura-Cretaceous Kootenay Group, Alberta and British Columbia

ABSTRACT Recent work in the Rocky Mountain Foothills and Front Ranges of southwestern Alberta and southeastern British Columbia has demonstrated that the economically important coal-bearing strata between the Jurassic Fernie Formation and the Lower Cretaceous Blairmore Group can be subdivided into three formations, which in ascending order are Morrissey (new), Mist Mountain (new), and Elk. Accordingly, it is proposed to elevate the former Kootenay Formation to group status, and at the same time re-establish the original definition and recognition of the Kootenay by including some older sandstone strata which have been transferred by previous workers into the Fernie Formation. The type section of the Morrissey Formation is on Morrissey Ridge, Elk River valley, British Columbia. This formation comprises a coarsening-upward sequence of massive, cliff-forming sandstone ranging in measured thickness from 20 m near Moose Mountain to a maximum of 80 m near Mist Mountain and Highwood Pass, southwestern Alberta. The formation can be subdivided into two members, the Weary Ridge (new), and the overlying Moose Mountain. The Weary Ridge Member, with designated type section on Weary Ridge in the upper Elk River valley of southeastern British Columbia, comprises an orange-brown to brownish-grey weathering, very fine to coarse-grained sandstone up to 55 m thick. The Moose Mountain Member, with type locality at Moose Mountain, Alberta, in contrast comprises a medium-grey weathering, fine- to coarse-grained, better-indurated and more massive sandstone, up to 36 m thick. The Mist Mountain Formation, stratigraphically equivalent to either the combined Adanac, Hillcrest and Mutz Members, or the Coal-Bearing member of the former Kootenay Formation, is proposed for an interbedded sequence of sandstone, siltstone, mudstone, shale and thin to thick seams of bituminous to semianthracite coal, up to 665 m thick. Exposures on a western spur of Mist Mountain near Highwood Pass in southwestern Alberta have been selected as the type section. The long-recognized Elk Formation extends geographically beyond the Fernie area, to other areas of southeastern British Columbia and southwestern Alberta. It comprises an interbedded succession of sandstone, siltstone, mudstone, shale and, locally, thick beds of chert pebble conglomerate and thin seams of high-volatile bituminous coal. A supplemental reference section is suggested for the formation on Morrissey Ridge south of Fernie, British Columbia. The Kootenay Group conformably overlies Upper Jurassic strata of the Fernie Formation and in most areas is disconformably overlain by Lower Cretaceous strata of the Blairmore Group. Near Fernie, Highwood Pass and Canmore, the Elk is possibly conformably overlain by the Pocaterra Creek Member of the Cadomin Formation (Blairmore Group). The Kootenay Group grades laterally into strata of the Nikanassin Formation in the vicinity of the North Saskatchewan River.

Birds of Moose Mountain, Saskatchewan, by Robert W. Nero and M. Ross Lein [Review

Birds of Moose Mountain, Saskatchewan, by Robert W. Nero and M. Ross Lein [Review

Seasonal changes of slough and lake water chemistry in Southern Saskatchewan (Canada)

Detailed hydrochemical studies of lakes and sloughs in the Moose Mountain area of Southern Saskatchewan showed an increase of the water salinity and the enrichment of waters with easily soluble salts during the summer season. This increase was accompanied by precipitation of the poorly soluble salts. The salinity and chemistry of the large lakes varied less than that of the smaller sloughs. The highly mineralized, shallow sloughs, located in deep kettles showed increases of salinity during summer of 200 to 300 per cent and particularly a sharp rise of sulphate and magnesium ions.

Cause and Control of Dolomite Distribution by Rock Selectivity

Research Article| January 01, 1967 Cause and Control of Dolomite Distribution by Rock Selectivity R. C MURRAY; R. C MURRAY University of New Mexico, Albuquerque, New Mexico Search for other works by this author on: GSW Google Scholar F. J LUCIA F. J LUCIA Shell Development Company, Houston, Texas Search for other works by this author on: GSW Google Scholar Author and Article Information R. C MURRAY University of New Mexico, Albuquerque, New Mexico F. J LUCIA Shell Development Company, Houston, Texas Publisher: Geological Society of America Received: 31 Jan 1966 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1967, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1967) 78 (1): 21–36. https://doi.org/10.1130/0016-7606(1967)78[21:CACODD]2.0.CO;2 Article history Received: 31 Jan 1966 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. C MURRAY, F. J LUCIA; Cause and Control of Dolomite Distribution by Rock Selectivity. GSA Bulletin 1967;; 78 (1): 21–36. doi: https://doi.org/10.1130/0016-7606(1967)78[21:CACODD]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Many sections of carbonate rocks exhibit abrupt changes from limestone to dolomite both vertically and laterally. The distribution pattern may be controlled by either the availability of a dolomitizing water or the physical-chemical character of the rock. The Turner Valley Formation exposed at Moose Mountain, Alberta, Canada, has been dolomitized where the original sediment was deposited as a carbonate mud with varying amounts of floating sand-sized and larger particles. Partially dolomitized limestones and possibly some completely dolomitized rocks were deposited as carbonate sands with interparticle lime mud. Those limestones which received less than 15 per cent dolomite were deposited as mud-free carbonate sands. The selectivity is believed to be due to permeability differences after predolomitization diagenesis or the greater reactivity to dolomitizing water of fine-grained sediment.Dolomite distribution is controlled by the distribution of lime mud. To understand the sedimentologic factors relating to the distribution of the lime mud, we have divided the carbonate rocks into two general categories depending on whether or not the sand-sized and larger particles show evidence of current transport. The mud-free carbonate sands in this study are considered to have been deposited from tidal currents. The sand-sized and larger particles of the mud-bearing dolomitic limestones and dolomites are interpreted as having been deposited essentially at their place of origin—noncurrent deposited. The ratio of sand-sized and larger particles to lime mud within the noncurrent-deposited sediments was controlled by the competing roles of particle production and lime-mud deposition.The current-deposited crinoidal sands and the noncurrent-deposited muddy sediments are visualized as being deposited contemporaneously. The current-deposited sands were derived from the reworking of noncurrent-deposited sediments by northeast-southwest-trending tidal currents. The crinoids and blastoids grew in greatest abundance near the edge of the areas of current deposition. The reduction in their population and the reduction in current velocity away from the areas of current deposition resulted in the reduced number of sand-sized particles and the increased amount of mud deposition. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Swallow Mortality at Moose Mountain

Swallow Mortality at Moose Mountain