Extension of lithofacies and conodont biofacies models of Late Devonian to Early Carboniferous carbonate ramp and black shale systems, southern Canadian Rocky Mountains

1999 ◽  
Vol 36 (8) ◽  
pp. 1281-1298 ◽  
Author(s):  
Lauret E Savoy ◽  
Anita G Harris ◽  
Eric W Mountjoy
Keyword(s):  
Rocky Mountains ◽  
Early Carboniferous ◽  
Carbonate Ramp ◽  
Canadian Rocky Mountains ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
Conodont Biofacies ◽  
Northwestern Montana ◽  
International Border

Uppermost Devonian and Lower Mississippian strata in the Rocky Mountains of southwestern Canada and northwestern Montana record widespread oceanographic changes during middle to late Paleozoic time associated with the termination of a carbonate ramp system, the onset of a deep-water, low-oxygen event and possible marginal tectonism, and the later reestablishment of a carbonate ramp. Integrated lithofacies and conodont biofacies developed previously for these strata between the Bow Valley and the international border have been extended northward to the Athabasca region of the Alberta Rocky Mountains. During early-middle Famennian time, the southern Canadian Rocky Mountains region was the site of a westward-deepening and westward-thickening carbonate ramp system (Palliser Formation). By late Famennian time carbonate ramp deposition ended and was followed by widespread deposition of organic-rich, low-oxygen facies in shelf to basinal environments (Exshaw Formation and correlative units). The overlying Banff Formation consists of anaerobic to marginally aerobic, starved-basin to deep-ramp lithofacies succeeded by shallower water carbonates; this sequence records basinward (westward) progradation of the Banff ramp in middle to late Tournaisian time. Distinct conodont biofacies representative of shallow-ramp to deep-basin settings that were previously recognized in the southernmost Canadian Rocky Mountains and Montana have also been identified to the north between the North Saskatchewan and Athabasca valleys. Upper Palliser carbonates contain low-diversity conodont faunas of indigenous to transported palmatolepid-, polygnathid-, and apatognathid-dominated assemblages. Exshaw deposits contain indigenous and reworked palmatolepid- and bispathodid-dominated assemblages and reworked or transported polygnathids. Lower Banff biofacies include transported and indigenous assemblages of siphonodellids, polygnathids, and pseudopolygnathids representative of the deep-middle Banff ramp. Polygnathid-hindeodid biofacies of shallower middle-ramp environments occur higher in the Banff Formation in the North Saskatchewan and Athabasca valleys.

Conodont biofacies and taphonomy along a carbonate ramp to black shale basin (latest Devonian and earliest Carboniferous), southernmost Canadian Cordillera and adjacent Montana

1993 ◽  
Vol 30 (12) ◽  
pp. 2404-2422 ◽  
Author(s):  
Lauret E. Savoy ◽  
Anita G. Harris
Keyword(s):  
Spatial Relations ◽  
Carbonate Ramp ◽  
Canadian Cordillera ◽  
Low Oxygen ◽  
Deep Basin ◽  
The West ◽  
Conodont Biofacies ◽  
Low Diversity ◽  
Shelf Seas ◽  
Oxygen Conditions

Uppermost Devonian – lowermost Carboniferous strata in the southernmost Canadian Cordillera and adjacent Montana record the onset and termination of low-oxygen conditions in carbonate-dominated epicontinental and shelf seas. Several distinct conodont biofacies representative of shallow-ramp to deep-basin settings are recognized on the basis of conodont distribution and preservation patterns.During early and middle Famennian time, the region was the site of a westward-deepening carbonate ramp (Palliser Formation) that was bordered to the west by a deep, shale basin (Lussier syncline strata). Palliser carbonates contain low-diversity conodont faunas of indigenous to transported Palmatolepis-, Polygnathus-, and Apatognathus-dominated assemblages. Basinal deposits yield a pelagic palmatolepid biofacies. Middle to late Famennian time was marked by termination of carbonateramp sedimentation and flooding of the margin with oxygen-depleted water. Deposition of organic-rich facies began in the expansa Zone in shelf to basin environments (Exshaw Formation and correlative units). These deposits contain indigenous pelagic Palmatolepis- and (or) Bispathodus-dominated assemblages; reworked or transported fragments are primarily polygnathids and icriodontids.Sedimentation of anaerobic to aerobic, deep-water, lower Banff facies occurred intermittently until middle Tournaisian and, locally, late Tournaisian time prior to westward progradation of younger carbonate deposits. Middle Tournaisian biofacies include transported and indigenous assemblages of siphonodellids (deep–middle ramp). Late Tournaisian biofacies parallel lithofacies changes associated with shallowing of the Banff sequence and are characterized by scaliognathid–doliognathid (basin to deep ramp), polygnathid and polygnathid–bactrognathid (deep to middle ramp), and bactrognathid–hindeodid (middle to shallow ramp) indigenous and displaced biofacies. The spatial relations of these Famennian and Tournaisian biofacies are generally consistent with models developed for correlative strata elsewhere.

scholarly journals Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input

2014 ◽  
Vol 11 (4) ◽  
pp. 977-993 ◽  
Author(s):  
I. Ruvalcaba Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

The taxonomic status of Timmia sibirica

1981 ◽  
Vol 59 (5) ◽  
pp. 563-571 ◽  
Author(s):  
Diana G. Horton
Keyword(s):  
North American ◽  
Rocky Mountains ◽  
Taxonomic Status ◽  
Distinct Species ◽  
Critical Study ◽  
Canadian Rocky Mountains ◽  
The North ◽  
Mixed Populations ◽  
Important Character

A critical study of the differentiating features of the North American populations of Timmia sibirica Lindb. et Arnell and T. norvegica Zett. reveals that populations with structure intermediate between these two taxa occur. Although from widespread localities, the intermediate specimens seem limited in number and T. sibirica and T. norvegica quite commnonly occur in mixed populations with no evidence of any intergradation. Therefore, it is concluded that the two taxa ought to be regarded as distinct species. The taxonomically important character-states of upper leaf cells and costa of T. sibirica. T. norvegica, and of the intermediate populations are illustrated with scanning elecron micrographs. The habitat of T. sibirica, like that of T. norvegica, is invariably on strongly calcareous substrates adjacent to waterfalls, along streams, or in low-lying tundra. The North American distribution of T. sibirica is mapped, including previously unreported localities as far south as 51° N in the Canadian Rocky Mountains.

scholarly journals Was the North Atlantic Ocean well-ventilated during Oceanic Anoxic Event 2 in the mid-Cretaceous?

2013 ◽  
Vol 10 (8) ◽  
pp. 13231-13276
Author(s):  
I. Ruvalcaba-Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
North Atlantic Ocean ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

II.—The Canadian Rockies. Part II: On some Rock-specimens collected by E. Whymper, Esq., F.R.S.E., in the Canadian Rocky Mountains

1902 ◽  
Vol 9 (12) ◽  
pp. 544-550
Author(s):  
T. G. Bonney
Keyword(s):  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Canadian Rockies ◽  
Eastern Side ◽  
North East ◽  
The North ◽  
Southern Side ◽  
Rock Specimens

The Canada Pacific Railway crosses the watershed of the Rocky Mountains at Hector or, as it is sometimes called, Kicking Horse Pass, and the specimens brought back by Mr. Whymper represent a district extending for some twenty miles on each side of the track, either on or west of the divide. The first group was obtained from summits lying near the railway on its southern side. Of these Mount Whyte is about three miles from it on the divide, which is crossed by Pope's Col just to the north of that summit, and about a mile to the north-east of the latter rises Mount St. Piran. About 3½ miles south of Mount Whyte, Mitre Col leads from the Lefroy to the Horseshoe glacier, between Mount Lefroy, which is on the divide, and Mitre Peak on the eastern side of it.

Holocene climate recorded by magnetic properties of lake sediments in the Northern Rocky Mountains, USA

The Holocene ◽  
2019 ◽  
Vol 30 (3) ◽  
pp. 479-484
Author(s):  
Daniel P Maxbauer ◽  
Mark D Shapley ◽  
Christoph E Geiss ◽  
Emi Ito
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rocky Mountains ◽  
Future Research ◽  
Magnetic Minerals ◽  
Holocene Climate ◽  
Northern Rocky Mountains ◽  
The North ◽  
Lake Bottom ◽  
Northern Rockies

We present two hypotheses regarding the evolution of Holocene climate in the Northern Rocky Mountains that stem from a previously unpublished environmental magnetic record from Jones Lake, Montana. First, we link two distinct intervals of fining magnetic grain size (documented by an increasing ratio of anhysteretic to isothermal remanent magnetization) to the authigenic production of magnetic minerals in Jones Lake bottom waters. We propose that authigenesis in Jones Lake is limited by rates of groundwater recharge and ultimately regional hydroclimate. Second, at ~8.3 ka, magnetic grain size increases sharply, accompanied by a drop in concentration of magnetic minerals, suggesting a rapid termination of magnetic mineral authigenesis that is coeval with widespread effects of the 8.2 ka event in the North Atlantic. This association suggests a hydroclimatic response to the 8.2 ka event in the Northern Rockies that to our knowledge is not well documented. These preliminary hypotheses present compelling new ideas that we hope will both highlight the sensitivity of magnetic properties to record climate variability and attract more work by future research into aridity, hydrochemical response, and climate dynamics in the Northern Rockies.

Wildfires in the southern Canadian Rocky Mountains and their relationship to mid-tropospheric anomalies

1993 ◽  
Vol 23 (6) ◽  
pp. 1213-1222 ◽  
Author(s):  
E.A. Johnson ◽  
D.R. Wowchuk
Keyword(s):  
North America ◽  
Rocky Mountains ◽  
Large Scale ◽  
Fire Frequency ◽  
Fuel Moisture ◽  
Large Fire ◽  
Canadian Rocky Mountains ◽  
Area Burned ◽  
Upper Level ◽  
Moisture Conditions

In this paper we present evidence for a large-scale (synoptic-scale) meteorological mechanism controlling the fire frequency in the southern Canadian Rocky Mountains. This large-scale control may explain the similarity in average fire frequencies and timing of change in average fire frequencies for the southern Canadian Rocky Mountains. Over the last 86 years the size distribution of fires (annual area burned) in the southern Canadian Rockies was distinctly bimodal, with a separation between small- and large-fire years at approximately 10–25 ha annual area burned. During the last 35 years, large-fire years had significantly lower fuel moisture conditions and many mid-tropospheric surface-blocking events (high-pressure upper level ridges) during July and August (the period of greatest fire activity). Small-fire years in this period exhibited significantly higher fuel moisture conditions and fewer persistent mid-tropospheric surface-blocking events during July and August. Mid-tropospheric surface-blocking events during large-fire years were teleconnected (spatially and temporally correlated in 50 kPa heights) to upper level troughs in the North Pacific and eastern North America. This relationship takes the form of the positive mode of the Pacific North America pattern.

Canadian Rocky Mountains

1903 ◽  
Vol 21 (6) ◽  
pp. 685
Author(s):  
J. Norman Collie
Keyword(s):  
Rocky Mountains ◽  
Canadian Rocky Mountains
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