Minette bodies and cognate mica-clinopyroxenite xenoliths from the Milk River area, southern Alberta: records of a complex history of the northernmost part of the Archean Wyoming craton

2000 ◽  
Vol 37 (11) ◽  
pp. 1629-1650 ◽  
Author(s):  
Arndt L Buhlmann ◽  
Patricia Cavell ◽  
Ronald A Burwash ◽  
Robert A Creaser ◽  
Robert W Luth
Keyword(s):  
Igneous Rocks ◽  
Coarse Grained ◽  
Geochemical Data ◽  
Tectonic Zone ◽  
Igneous Complex ◽  
Wyoming Craton ◽  
Mantle Enrichment ◽  
Southern Alberta ◽  
Igneous Province ◽  
History Of

Minettes exposed in southern Alberta near the Milk River are the northern outliers of the Eocene Sweet Grass Hills igneous complex of the Montana alkalic igneous province. These minettes often contain coarse-grained xenoliths of phlogopite + clinopyroxene ± apatite. The parent magmas of the minettes were generated at pressures [Formula: see text]17 kbar in equilibrium with clinopyroxene + phlogopite ± olivine. Fractional crystallization and mixing provided a spectrum of evolved minettes and cumulates, the latter of which were sampled by subsequent minette magmas as xenoliths. Two xenoliths were dated at 49.0 ± 0.8 Ma and 52 ± 1.7 Ma. The host dyke of the latter xenolith gave an age of 50 ± 0.3 Ma. The minettes and their xenoliths have overlapping values of 87Sr/86Sri, εNdT, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, similar to those of alkaline igneous rocks from farther south in the Montana alkalic igneous province. The Sweet Grass Hills lie north of the Great Falls Tectonic Zone, previously interpreted as a Proterozoic suture zone separating the Archean Medicine Hat block from the Archean Wyoming craton to the south. Geochemical data for the Milk River minettes provide evidence for a history of the mantle underneath the Medicine Hat block, similar to that found previously for mantle-derived rocks of the Wyoming craton, including a significant Proterozoic mantle enrichment event. Given this similarity, we suggest that the Wyoming craton extends into southern Alberta, and that the Great Falls Tectonic Zone does not represent a Proterozoic suture of two Archean blocks.

scholarly journals The Medicine Hat Block and the Early Paleoproterozoic Assembly of Western Laurentia

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 271
Author(s):  
Jennifer N. Gifford ◽  
Shawn J. Malone ◽  
Paul A. Mueller
Keyword(s):  
Ocean Basin ◽  
Geochemical Data ◽  
Drill Core ◽  
Tectonic Zone ◽  
Aggregation Model ◽  
Wyoming Craton ◽  
Crystalline Crust ◽  
Wyoming Province ◽  
Crustal Xenoliths ◽  
Complex Block

The accretion of the Wyoming, Hearne, and Superior Provinces to form the Archean core of western Laurentia occurred rapidly in the Paleoproterozoic. Missing from Hoffman’s (1988) original rapid aggregation model was the Medicine Hat block (MHB). The MHB is a structurally distinct, complex block of Precambrian crystalline crust located between the Archean Wyoming Craton and the Archean Hearne Province and overlain by an extensive Phanerozoic cover. It is distinguished on the basis of geophysical evidence and limited geochemical data from crustal xenoliths and drill core. New U-Pb ages and Lu-Hf data from zircons reveal protolith crystallization ages from 2.50 to 3.28 Ga, magmatism/metamorphism at 1.76 to 1.81 Ga, and εHfT values from −23.3 to 8.5 in the Archean and Proterozoic rocks of the MHB. These data suggest that the MHB played a pivotal role in the complex assembly of western Laurentia in the Paleoproterozoic as a conjugate or extension to the Montana Metasedimentary Terrane (MMT) of the northwestern Wyoming Province. This MMT–MHB connection likely existed in the Mesoarchean, but it was broken sometime during the earliest Paleoproterozoic with the formation and closure of a small ocean basin. Closure of the ocean led to formation of the Little Belt arc along the southern margin of the MHB beginning at approximately 1.9 Ga. The MHB and MMT re-joined at this time as they amalgamated into the supercontinent Laurentia during the Great Falls orogeny (1.7–1.9 Ga), which formed the Great Falls tectonic zone (GFTZ). The GFTZ developed in the same timeframe as the better-known Trans-Hudson orogen to the east that marks the merger of the Wyoming, Hearne, and Superior Provinces, which along with the MHB, formed the Archean core of western Laurentia.

scholarly journals Mineralogical and Geochemical Constraints on Magma Evolution and Late-Stage Crystallization History of the Breivikbotn Silicocarbonatite, Seiland Igneous Province in Northern Norway: Prerequisites for Zeolite Deposits in Carbonatite Complexes

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 537 ◽  
Author(s):  
Dmitry Zozulya ◽  
Kåre Kullerud ◽  
Erling Ravna ◽  
Yevgeny Savchenko ◽  
Ekaterina Selivanova ◽  
...  
Keyword(s):  
Trace Element ◽  
Tectonic Setting ◽  
Spatial Proximity ◽  
Geochemical Data ◽  
Chemical Compositions ◽  
Igneous Province ◽  
Magmatic Stage ◽  
Stage Crystallization ◽  
History Of ◽  
Late Magmatic Stage

The present work reports on new mineralogical and whole-rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, magnetite and zircon as minor and accessory minerals, and it is classified as silicocarbonatite. Calcite, titanite and pyroxene (Di36–46 Acm22–37 Hd14–21) are primarily magmatic minerals. Amphibole of mainly hastingsitic composition has formed after pyroxene at a late-magmatic stage. Zeolite group minerals (natrolite, gonnardite, Sr-rich thomsonite-(Ca)) were formed during hydrothermal alteration of primary nepheline by fluids/solutions with high Si-Al-Ca activities. Poikilitic garnet (Ti-bearing andradite) has inclusions of all primary minerals, amphibole and zeolites, and presumably crystallized metasomatically during a late metamorphic event (Caledonian orogeny). Whole-rock chemical compositions of the silicocarbonatite differs from the global average of calciocarbonatites by elevated silica, aluminium, sodium and iron, but show comparable contents of trace elements (REE, Sr, Ba). Trace element distributions and abundances indicate within-plate tectonic setting of the carbonatite. The spatial proximity of carbonatite and alkaline ultramafic rock (melteigite), the presence of “primary nepheline” in carbonatite together with the trace element distributions indicate that the carbonatite was derived by crystal fractionation of a parental carbonated foidite magma. The main prerequisites for the extensive formation of zeolite group minerals in silicocarbonatite are revealed.

scholarly journals Mineralogical and Geochemical Constraints on the Origin and Late-Stage Crystallization History of the Breivikbotn Silicocarbonatite, Seiland Igneous Province in Northern Norway: Prerequisites for Zeolite Deposits in Carbonatite Complexes

2018 ◽  
Author(s):  
Dmitry Zozulya ◽  
Kåre Kullerud ◽  
Erling Ravna ◽  
Yevgeny Savchenko ◽  
Ekaterina Selivanova ◽  
...  
Keyword(s):  
Trace Element ◽  
Tectonic Setting ◽  
Spatial Proximity ◽  
Geochemical Data ◽  
Chemical Compositions ◽  
Igneous Province ◽  
Magmatic Stage ◽  
Stage Crystallization ◽  
History Of ◽  
Late Magmatic Stage

The present work reports new mineralogical and whole rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, magnetite and zircon as minor and accessory minerals, and it is classified as silicocarbonatite. Calcite, titanite and pyroxene (Di36-46 Acm22-37 Hd14-21) are primarily magmatic minerals. Amphibole of hastingsitic composition has formed after pyroxene at a late-magmatic stage. Zeolite group minerals (natrolite, gonnardite, Sr-rich thomsonite-(Ca)) were formed during hydrothermal alteration of primary nepheline by fluids/solutions with high Si-Al-Ca activities. Poikilitic garnet (Ti-bearing andradite) has inclusions of all primary minerals, amphibole and zeolites, and presumably crystallized metasomatically during a late metamorphic event (Caledonian orogeny). Whole rock chemical compositions of the silicocarbonatite differs from the global average of calciocarbonatites by elevated silica, aluminium, sodium and iron, but show comparable contents of trace elements (REE, Sr, Ba). Trace element distributions indicate within-plate tectonic setting of the carbonatite. The spatial proximity of carbonatite and alkaline ultramafic rock (melteigite), the presence of “primary nepheline” in carbonatite together with the trace element distributions indicate that the carbonatite was derived from crystal fractionation of a parental carbonated foidite magma. The main prerequisites for the extensive formation of zeolite group minerals in silicocarbonatite are revealed.

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

A history of Albertosaurus discoveries in Alberta, CanadaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus.

2010 ◽  
Vol 47 (9) ◽  
pp. 1197-1211 ◽  
Author(s):  
Darren H. Tanke ◽  
Philip J. Currie
Keyword(s):  
New Genus ◽  
Geographic Range ◽  
Special Issue ◽  
Southern Alberta ◽  
Considerable Confusion ◽  
Taxonomic Uncertainty ◽  
History Of ◽  
Information Politics ◽  
Horseshoe Canyon Formation

After many years of taxonomic uncertainty, Albertosaurus was established as a new genus in 1905, the year Alberta became a province of Canada. Gorgosaurus is a closely related tyrannosaurid from the Judithian beds of southern Alberta that was subsequently synonymized with Albertosaurus. Although most researchers consider the genera as distinct, there has been considerable confusion over the temporal and geographic range of Albertosaurus. Albertosaurus sarcophagus is only known from 13 skulls and (or) skeletons of varying completeness, and one (possibly two) bonebeds, all from the Horseshoe Canyon Formation (Campanian–Maastrichtian) of Alberta. Many of the major Albertosaurus specimens are scientifically compromised due to poor collection techniques, incomplete locality and stratigraphic information, politics, vandalism, accidents, gunplay, and landowner issues. The background of each specimen is discussed to eliminate some of the sources of confusion and to document how much of each specimen is preserved.

Stratigraphic and sedimentological characterisation of the Late Cretaceous post-rift intra Lange Sandstones of the Gimsan Basin and Grinda Graben (Halten Terrace, Norwegian Sea)

2021 ◽  
pp. SP495-2021-72
Author(s):  
Domenico Chiarella ◽  
Daniel Joel
Keyword(s):  
Late Cretaceous ◽  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Coarse Grained ◽  
Borehole Data ◽  
Norwegian Sea ◽  
Marine Gravity ◽  
History Of ◽  
Gravity Driven ◽  
Reservoir Potentiality

AbstractDeep-marine gravity-driven deposits represent one of the more investigated depositional systems due to their potential interest as target for exploration and carbon capture and storage activities, as well as an important record of the depositional history of a basin through time. Although the Halten Terrace (Norwegian Sea) is one of the main successful exploration areas, we still have poor understanding of the post-rift Cretaceous interval. Here, 3D seismic reflection and borehole data are integrated to investigate the stratigraphic distribution and sedimentological characteristics of the Cenomanian-Turonian intra Lange Sandstones in the Gimsan Basin and Grinda Graben. The Lange Formation records the deposition in a deep-marine environment of a thousand meter thick shale unit punctuated by tens of meters thick gravity-driven coarse-grained sandstone intervals sourced from the Norwegian mainland. The presence of gravity-driven deposits and the deep-marine setting is supported by seismic interpretation, architectural elements and the facies analysis of cored material acquired within the studied stratigraphic interval. Borehole data indicate the presence of both turbidites and hybrid-event beds rich in mud content. The results of this study have implications for the understanding of the distribution and reservoir potentiality of the Late Cretaceous Lange Formation in the Halten Terrace.

scholarly journals Lake-level variability in Salar de Coipasa, Bolivia during the past ∼40,000 yr

2018 ◽  
Vol 91 (2) ◽  
pp. 881-891 ◽  
Author(s):  
J. Andrew Nunnery ◽  
Sherilyn C. Fritz ◽  
Paul A. Baker ◽  
Wout Salenbien
Keyword(s):  
Lake Level ◽  
Sediment Accumulation ◽  
Geochemical Data ◽  
South American ◽  
Climate History ◽  
Oxygen Isotope Stage ◽  
The Past ◽  
History Of ◽  
Diatom Stratigraphy ◽  
The Last Glacial

AbstractVarious paleoclimatic records have been used to reconstruct the hydrologic history of the Altiplano, relating this history to past variability of the South American summer monsoon. Prior studies of the southern Altiplano, the location of the world’s largest salt flat, the Salar de Uyuni, and its neighbor, the Salar de Coipasa, generally agree in their reconstructions of the climate history of the past ∼24 ka. Some studies, however, have highly divergent climatic records and interpretations of earlier periods. In this study, lake-level variation was reconstructed from a ∼14-m-long sediment core from the Salar de Coipasa. These sediments span the last ∼40 ka. Lacustrine sediment accumulation was apparently continuous in the basin from ∼40 to 6 ka, with dry or very shallow conditions afterward. The fossil diatom stratigraphy and geochemical data (δ13C, δ15N, %Ca, C/N) indicate fluctuations in lake level from shallow to moderately deep, with the deepest conditions correlative with the Heinrich-1 and Younger Dryas events. The stratigraphy shows a continuous lake of variable depth and salinity during the last glacial maximum and latter stages of Marine Oxygen Isotope Stage 3 and is consistent with environmental inferences and the original chronology of a drill core from Salar de Uyuni.

Crystallisation of fine- and coarse-grained A-type granite sheets of the Southern Oklahoma Aulacogen, U.S.A.

2000 ◽  
Vol 91 (1-2) ◽  
pp. 139-150 ◽  
Author(s):  
John P. Hogan ◽  
M. Charles Gilbert ◽  
Jon D. Price
Keyword(s):  
Solidus Temperature ◽  
Direct Consequence ◽  
Progressive Increase ◽  
Coarse Grained ◽  
Fine Grained ◽  
Mafic Complex ◽  
Southern Oklahoma ◽  
History Of ◽  
Volcanic Pile ◽  
Crustal Magma

A-type felsic magmatism associated with the Cambrian Southern Oklahoma Aulacogen began with eruption of voluminous rhyolite to form a thick volcanic carapace on top of an eroded layered mafic complex. This angular unconformity became a crustal magma trap and was the locus for emplacement of later subvolcanic plutons. Rising felsic magma batches ponding along this crustal magma trap crystallised first as fine-grained granite sheets and then subsequently as coarser-grained granite sheets. Aplite dykes, pegmatite dykes and porphyries are common within the younger coarser-grained granite sheets but rare to absent within the older fine-grained granite sheets. The older fine-grained granite sheets typically contain abundant granophyre.The differences between fine-grained and coarse-grained granite sheets can largely be attributed to a progressive increase in the depth of the crustal magma trap as the aulacogen evolved. At low pressures (<200MPa) a small increase in the depth of emplacement results in a dramatic increase in the solubility of H2O in felsic magmas. This is a direct consequence of the shape of the H2O-saturated granite solidus. The effect of this slight increase in total pressure on the crystallisation of felsic magmas is to delay vapour saturation, increase the H2O content of the residual melt fractions and further depress the solidus temperature. Higher melt H2O contents, and an extended temperature range over which crystallisation can proceed, both favour crystallisation of coarser-grained granites. In addition, the potential for the development of late, H2O-rich, melt fractions is significantly enhanced. Upon reaching vapour saturation, these late melt fractions are likely to form porphyries, aplite dykes and pegmatite dykes.For the Southern Oklahoma Aulacogen, the progressive increase in the depth of the crustal magma trap at the base of the volcanic pile appears to reflect thickening of the volcanic pile during rifting, but may also reflect emplacement of earlier granite sheets. Thus, the change in textural characteristics of granite sheets of the Wichita Granite Group may hold considerable promise as an avenue for further investigation in interpreting the history of this rifting event.

Paleomagnetic history of the Mealy dykes of Labrador, Canada

1983 ◽  
Vol 20 (12) ◽  
pp. 1818-1833 ◽  
Author(s):  
J. K. Park ◽  
R. F. Emslie
Keyword(s):  
The Other ◽  
Magnetic Mineral ◽  
Magnetic Minerals ◽  
Linear Distribution ◽  
Tectonic Zone ◽  
Magnetic Components ◽  
History Of ◽  
Component C ◽  
A Site

Paleomagnetic analysis of the Mealy diabase dykes of Labrador reveals magnetizations that predate the Grenville event at about 1000 Ma. These dykes intrude the Mealy Mountains anorthositic complex in the Grenville Structural Province. They are well south of the Grenville Front Tectonic Zone, but were apparently never subjected to temperatures as high as 500 °C during their post-consolidation history.Four distinct magnetic components were uncovered by thermal and alternating field treatments and a fifth remained unresolved. The major magnetic mineral present, titanomagnetite, is thought to record two magnetic directions acquired during cooling from magmatic temperatures. These are B (D = 305°, I = −76°; N = 18 sites; κ = 12; α95 = 11°) and A (D = 095°, I = +52°; N = 20 sites; κ = 46; α95 = 5°). Component B has much within-site dispersion. The other two components, C (D = 274°, I = −47°; N = 10 sites; κ = 15; α95 = 13°) and D (D = 292°, I = −74°; κ = 5; α95 = 31°), probably reside in magnetite and pyrrhotite, respectively. Component C, antiparallel to A, was probably acquired at about the same time as A. We suggest that C and A represent the first stable magnetizations retained by the dykes following an extensive period of cooling and re-equilibration of the magnetic minerals. Components B and D, which agree in direction, represent a later stage of cooling.Component B has a pole at 148°E, 34°S (δp = 18°, δm = 19°) in agreement with regional metamorphic poles from the Grenville; A, however, has a pole at 173°W, 23°S (δp = 5°, δm = 7°), which apparently "sees through" the peak in Grenville activity. The A site poles have a linear distribution along the Keweenawan Track and probably relate to an age between 1000 and 1150 Ma.

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