Frontenac Terrane Research Articles

The Grenville Orogenic Cycle (ca. 1350-1000 Ma): an Adirondack perspective

The Adirondack Mountains are characterized by three major events that took place during the interval ca. 1350-1000 Ma. The earliest of these is the arc-related Elzevirian Orogeny (ca. 1350-1185 Ma) during which substantial volumes of juvenile calc-alkaline crust were added to the Adirondacks as well as to the northwest segment of the Central Metasedimentary Belt. Data from the southwestern United States as well as from Ireland and Baltica indicate that Elzevirian magmatism and orogeny were of global dimensions. Within the southwestern sector of the Grenville Province, the Elzevirian Orogeny culminated at ca. 1185 Ma when accretion of all outboard terranes was completed. Compressional orogeny related to this convergence resulted in overthickened crust and lithosphere which subsequently delaminated giving rise to orogen collapse and AMCG magmatism that swept southeastward from the Frontenac Terrane into the Adirondack Highlands during the interval ca. 1180-1130 Ma. Localized compressional events within neighboring parts of the Grenville Province emphasize the continued existence of contraction during this interval, although crustal extension caused local in sedimentary basins in which were deposited the Flinton and the St. Boniface Groups. The Adirondacks have not yet provided any record of events within the interval ca. 1125-1100 Ma, although there is evidence of contraction elsewhere in the southwestern Grenville Province at that time. At 1100-1090 Ma the northern Adirondack Highlands were invaded by mildly A-type hornblende granites (Hawkeye suite) that are interpreted to be the result of local crustal thinning contemporaneous with rifting and mafic magmatism taking place in the Midcontinent rift. Immediately following, at ca. 1090 Ma, the global-scale continental collision of the Ottawan Orogeny was initiated. Strong convergence, deformation, and metamorphism continued to at least ca. 1070 Ma, and rocks older than this are profoundly affected by this event. During the waning stages of the Ottawan Orogeny, overthickened crust and lithosphere delaminated and the orogen underwent collapse. Large extensional faults such as the Carthage-Colton-Labelle shear zone developed and rapidly exhumed granulite facies rocks in the mobile core of the orogen which centers on the Adirondack-Morin terranes and extends southeastward into the New York-New Jersey Highlands. Extensional faulting along the Carthage-Colton mylonite zone dropped the amphibolite facies Lowlands down to the west and into juxtaposition with granulite facies rocks of the Highlands. UPb cooling ages from garnet, monazite, and titanite exhibit a sufficiently broad spectrum to accommodate an initial rapid rate of rebound-related cooling followed by a slower, erosion-controlled cooling history. During delamination, late- to post-tectonic granites of the Lyon Mt. Gneiss (ca. 1070-1045 Ma) were emplaced. The youngest member of this suite is an undeformed fayalite granite dated at ca. 1045 Ma which crosscuts all older rocks and fabric. High-potassium, post-tectonic granites of similar age are common in other parts of the southwestern Grenville Province. Renewed contraction and metamorphism at ca. 1030 Ma demonstrate that the Ottawan Orogen was still experiencing convergence well after the peak of orogeny. However, most of the manifestations involve reactivation of older thrust faults, including the Grenville Front Tectonic Zone. The intrusion of small bodies of anorthosite at ca. 1015 Ma (i.e., Labrieville) provide further evidence for the emplacement of these rocks within collisional orogens, albeit in their collapsing phase.

The Parry Sound domain: a far-travelled allochthon? New evidence from U–Pb zicon geochronology

We report U–Pb zircon ages for metaplutonic and metasedimentary rocks from three lithotectonic assemblages within the Parry Sound allochthon of the Central Gneiss Belt, southwestern Grenville Orogen: the basal Parry Sound, interior Parry Sound, and Twelve Mile Bay assemblages. Magmatic crystallization ages for granitic to tonalitic gneisses from the basal Parry Sound assemblage fall in the range 1400–1330 Ma. Younger intrusions include the Parry Island anorthosite dated at 1163 ± 3 Ma and a crosscutting mafic dyke bracketed between 1151 and 1163 Ma. Dated at [Formula: see text] a tonalitic gneiss from the overlying interior Parry Sound assemblage is slightly younger than the older group of rocks from the basal Parry Sound assemblage. 207Pb/206Pb ages for zircons from a quartzite of the basal Parry Sound assemblage range from 1385 Ma to the Neoarchaean. An absolute maximum age for this quartzite is 1436 ± 17 Ma. In contrast, detrital zircons from a quartzite of the Twelve Mile Bay assemblage constrain the age of deposition at post-ca. 1140–1120 Ma. We speculate that Grenvillian-age zircons within this quartzite were derived from rocks in the Adirondack Highlands and Frontenac terrane, implying that part of the Parry Sound domain and these terranes were contiguous during deposition of the quartzite. Our data support previous interpretations that the Parry Sound domain is allochthonous with respect to its surroundings, and suggest that the most likely source region of the basal Parry Sound domain lies southeast of the Central Gneiss Belt, within the Central Metasedimentary Belt boundary thrust zone or the Adirondack Highlands. This implies the possibility of 100–300 km of displacement of the domain. Emplacement of the Parry Sound domain into its present position must have occurred relatively late in the orogen's history, by about 1080 Ma.

Seismic structure of the Central Metasedimentary Belt, southern Grenville Province

Crust and upper-mantle structure interpreted from wide-angle seismic data along a 260 km profile across the Central Metasedimentary Belt of the southern Grenville Province in Ontario and New York State shows (i) relatively high average crustal and uppermost mantle velocities of 6.8 and 8.3 km/s, respectively; (ii) east-dipping reflectors extending to 24 km depth in the Central Metasedimentary Belt; (iii) weak lateral velocity variations beneath 5 km; (iv) a mid-crustal boundary at 27 km depth; and (v) a depth to Moho of 43–46 km. The wide-angle model is generally consistent with the vertical-incidence reflectivity of an intersecting Lithoprobe reflection line. The mid-crustal boundary correlates with a crustal detachment zone in the Lithoprobe data and the depth extent of east-dipping wide-angle reflectors. Regional structure and aeromagnetic anomaly trends support the southwest continuity of Grenville terranes and their boundaries from the wide-angle profile to two reflection lines in Lake Ontario. A zone of wide-angle reflectors with an average apparent eastward dip of 13° has a surface projection that correlates spatially with the boundary between the Elzevir and Frontenac terranes of the Central Metasedimentary Belt and resembles reflection images of a crustal-scale shear zone beneath Lake Ontario. A high-velocity upper-crustal anomaly beneath the Elzevir–Frontenac boundary zone is positioned in the hanging wall associated with the concentrated zone of wide-angle reflectors. The high-velocity anomaly is coincident with a gravity high and increased metamorphic grade, suggesting northwest transport of mid-crustal rocks by thrust faulting consistent with the mapped geology. The seismic data suggest (i) a reflective, crustal-scale structure has accommodated northwest-directed tectonic transport within the Central Metasedimentary Belt; (ii) this structure continues southwest from the exposed Central Metasedimentary Belt to at least southern Lake Ontario; and (iii) crustal reflectivity and complexity within the eastern Central Metasedimentary Belt is similar to that observed at the Grenville Front and the western Central Metasedimentary Belt boundary.

Deep structure beneath Lake Ontario: crustal-scale Grenville subdivisions

Lake Ontario marine seismic data reveal major Grenville crustal subdivisions beneath central and southern Lake Ontario separated by interpreted shear zones that extend to the lower crust. A shear zone bounded transition between the Elzevir and Frontenac terranes exposed north of Lake Ontario is linked to a seismically defined shear zone beneath central Lake Ontario by prominent aeromagnetic and gravity anomalies, easterly dipping wide-angle reflections, and fractures in Paleozoic strata. We suggest the central Lake Ontario zone represents crustal-scale deformation along an Elzevir–Frontenac boundary zone that extends from outcrop to the south shore of Lake Ontario.Seismic images from Lake Ontario and the exposed western Central Metasedimentary Belt are dominated by crustal-scale shear zones and reflection geometries featuring arcuate reflections truncated at their bases by apparent east-dipping linear reflections. The images show that zones analogous to the interpreted Grenville Front Tectonic Zone are also present within the Central Metasedimentary Belt and support models of northwest-directed crustal shortening for Grenvillian deep crustal deformation beneath most of southeastern Ontario.A Precambrian basement high, the Iroquoian high, is defined by a thinning of generally horizontal Paleozoic strata over a crestal area above the basement shear zone beneath central Lake Ontario. The Iroquoian high helps explain the peninsular extension into Lake Ontario forming Prince Edward County, the occurrence of Precambrian inlier outcrops in Prince Edward County, and Paleozoic fractures forming the Clarendon–Linden structure in New York.

Geochronology of detrital zircons from the Elzevir and Frontenac terranes, Central Metasedimentary Belt, Grenville Province, Ontario: Discussion

The paper by E.A. Sager-Kinsman and R.R. Parrish represents a valuable contribution to the ongoing effort to unravel the tectonic magmatic history of the Central Metasedimentary Belt in the Grenville Province. However, we feel that some of the implications of this study have been understated by the authors, particularly with respect to the understanding of the evolution of the margin of the North American craton during the Middle Proterozoic. Our discussion focuses on three specific areas of the authors' study, namely, (1) implications of their study to the published tectono-stratigraphy of the Frontenac Terrane; (2) implications with respect to the age of the Frontenac Terrane relative to the remainder of the Central Metasedimentary Belt in Ontario; and (3) implications with respect to the distribution of 1.8 Ga orogenic belts in North America and reconstruction of Laurentia during the Middle Proterozoic.

Geochronology of detrital zircons from the Elzevir and Frontenac terranes, Central Metasedimentary Belt, Grenville Province, Ontario: Reply

The Central Metasedimentary Belt (CMB) of the Grenville Province contains metasedimentary sequences belonging to a number of distinct tectono-stratigraphic terranes whose depositional ages are poor...

Geochronology of detrital zircons from the Elzevir and Frontenac terranes, Central Metasedimentary Belt, Grenville Province, Ontario

The Central Metasedimentary Belt (CMB) of the Grenville Province contains metasedimentary sequences belonging to a number of distinct tectono-stratigraphic terranes whose depositional ages are poorly known. This study provides information on not only the provenance, but also the maximum age of clastic rocks in two of these terranes, the Elzevir Terrane on the northwest and the Frontenac Terrane to its southeast, adjacent to the Adirondack Mountains of New York.The Flinton Group, a component of the Elzevir Terrane, is a distinctive, mostly clastic, sedimentary sequence that unconformably overlies igneous and metavolcanic rocks of the main part of Elzevir Terrane of the CMB. Analyzed zircons from quartzose metasediments of the Flinton Group are 0–2% discordant and range in age from 1150 to 1335 Ma, with older rounded grains at 1461 ± 5 and 1877 ± 3 Ma. The quartzite was therefore deposited after ca. 1150 Ma, indicating that the Flinton Group is more than 100 Ma younger than the intrusion of the underlying Elzevir batholith. We speculate that 1150–1180 Ma zircons within the Flinton Group were derived from plutons in the Frontenac Terrane to the southeast, implying that the Elzevir and Frontenac terranes were contiguous during Flinton Group deposition. Subsequent metamorphism of the Flinton Group occured between 1150 and 1080 Ma.The high-grade Frontenac Terrane of the CMB lies southeast of Elzevir Terrane, and contains marble associated with pelitic gneiss and quartzite, as well as granitic intrusive rocks; it resembles a metamorphosed continental margin sedimentary sequence. U–Pb analyses of zircons from quartzites from two different localities are generally less than 5% discordant, but show stronger evidence for Grenvillian Pb loss than zircons from the Flinton Group. 207Pb/206Pb ages range from 1493 to 2580 Ma, with one analysis (2% discordant) at 1306 ± 16 Ma, another at 3185 ± 3 Ma, and a cluster of ages between 1745 and 1892 Ma. Detrital zircon ages are, for the most part, distinctly older than in the Flinton Group. The age of this quartzite sequence is tentatively regarded as less than ca. 1300 Ma (based on one grain), but is certainly less than 1500 Ma. It could therefore have been deposited during the same time interval as the 1.2–1.3 Ga metasedimentary and metavolcanic rocks of the Elzevir Terrane. Although Frontenac Terrane experienced metamorphism along with Elzevir Terrane around 1.1 Ga, the principle metamorphic culmination in the Frontenac occurred prior to 1170 Ma.

Sm-Nd and U-Pb Isotopic Evidence of Juvenile Crust in the Adirondack Lowlands and Implications for the Evolution of the Adirondack Mts.

Sm-Nd investigations of Hyde School Gneiss yield $T_{DM}$ ages only slightly older than U-Pb zircon emplacement ages thus indicating substantial addition of juvenile, calcalkaline crust to the Adirondack lowlands at ca. 1300 Ma. Juvenile crust of similar age has been recognized within the Adirondack highlands, the Elzevir terrane further to the northwest in Canada, and in the Green Mts. of Vermont suggesting the presence of an extensive magmatic arc at that time. While the precise nature of the arc remains uncertain, an Indonesian analogue is favored. U-Pb zircon ages of ca. 1150-1160 Ma are reported for lowlands samples of syenitic and granitic rocks belonging to the anorthosite-mangerite-charnockite-granite (AMCG) suite that also occurs in the highlands, as well as in the Canadian sector of the Frontenac terrane. The regional occurrence of these anorogenic intrusions indicates that the Adirondack highlands and Frontenac terrane, including the Adirondack lowlands, constituted a single, contiguous entity by ca. 1160 Ma. Monazite ages from AMCG rocks and metamorphic zircons from Hyde School Gneiss indicate that the last high grade metamorphism (i.e., upper amphibolite facies) in the Adirondack lowlands occurred at ca. 1150 Ma. The presence of 1050 Ma granulite facies assemblages east of the Carthage-Colton mylonite zone (CCMZ) in the highlands indicates the presence of a discontinuity across the CCMZ, which may manifest ca. 1050 Ma downfaulting of the lowlands block along the northwest dipping CCMZ in response to verthickened crust during the Ottawan orogeny.

Metallogeny of structural zones, Grenville Province, northeastern North America

Recent subdivision of the Grenville Province into Northwestern, Central and Southeastern tectonic zones provides a convenient basis for describing the tectonic affiliation of the contained mineral deposits. The Northwestern zone consists of reworked foreland lithologies southeast of the Grenville Front. Major deposits of metamorphosed Superior-type iron formations are present in metamorphosed Kaniapiscau Supergroup equivalents, exposed at lower metamorphic grades in the Labrador trough. Occurrences of volcanogenic massive sulphides (Abitibi Group equivalents), NiCu, quartzite-hosted UAu, and alkaline intrusion-hosted REE's are of only mineralogical importance. The Central zone contains polydeformed gneisses that have been intruded by three ages of anorogenic anorthosite massifs (circa 1.64, 1.36, and 1.14 Ga) and associated charnockite/magnerite complexes. Major magmatic Ti-Fe (Lac Allard) and large, low-grade NiCu (McNickel) deposits are associated with the younger anorthosite suite. Magmatic NiCu also occurs in differentiated metapyroxenite/metaperidotite of uncertain age. Pegmatites are widespread but not commercially important. The Southeastern zone consists of the rocks of the Central Metasedimentary Belt (CMB) and Central Granulite Terrane (CGT) as well as rocks of the relatively unmetamorphosed Wakeham Supergroup. Initial deposition of volcanic and carbonate rocks occurred in the CMB between 1.28 and 1.24 Ga and was followed by deposition of the Flinton Group ∼1.15 Ga. The rocks are overprinted by the Elzeviran and Ottawan orogenies ∼1.25 and 1.08 Ga respectively. Volcanogenic ZnPbAgAu deposits and SEDEX marble-hosted Zn deposits occur widely in the layered rocks of the Central Metasedimentary Belt (deposition ∼1.28 Ga). Small massive sulphide and shale hosted base metal occurrences and both oxide and sulphide iron formations are widespread near volcanic lithologies but are generally small or very low-grade. Syngenetic-magmatic deposits include subeconomic FeTi and NiCu deposits that are syntectonic with respect to the Ottawan orogeny but others may be as old as Elzeviran. Small magnetite-rich skarn deposits are widespread, with 2 major past-producing deposits, and are related to magmatic events accompanying the Elzeviran orogeny. Gold and gold sulphosalt occurrences in Grenville volcanic and carbonate lithologies and Flinton Group rocks of various types are not well constrained in age. Some are spatially associated with older Elzeviran intrusions and have been genetically related to them, others exhibit metamorphic textures but cut younger Flinton group rocks while others appear to be completely post-metamorphic. Extensive pegmatitic and related skarn and carbonate vein U ± Mo ± REE occurrences may relate either to metamorphic or intrusive processes related to the Ottawan orogeny. In the CGT, FeTi and NiCu occurrences associated with the younger anorogenic anorthosite massifs are similar to occurrences in the Central zone. Large fluorite-bearing magnetite iron deposits associated with alaskitic gneisses are interpreted as similar to the Swedish Kiruna-type deposits. Following stabilization of the Grenville craton, rifting associated with the opening of Iapetus in the latest Proterozoic-Cambrian and again in the Cretaceous resulted in the regional intrusion of alkaline complexes which included large Nb-and REE-rich carbonatite intrusions. In the Cretaceous, rift-related faults became the sites of small fluorite-barite-galenastrontianite deposits over a wide area in the Elzevir and Frontenac terranes and in the Charlevoix-Saguenay area of the Central Zone.

Differential unroofing within the central metasedimentary Belt of the Grenville Orogen: constraints from 40Ar/39Ar thermochronology

An 40Ar/39Ar thermochronological investigation of upper greenschist to granulite facies gneiss, amphibolite and marble was conducted in the Central Metasedimentary Belt (CMB), Ontario, to constrain its cooling history. Incremental 40Ar/39Ar release spectra indicate that substantial differential unroofing occurred in the CMB between ∼ 1000 and ∼ 600 Ma. A consistent pattern of significantly older hornblende and phlogopite 40Ar/3Ar cooling ages on the southeast sides of major northeast striking shear zones is interpreted to reflect late displacement due to extensional deformation. Variations in hornblende 40Ar/39Ar age plateaus exceeding 200 Ma occur over distances less than 50 km with major age discontinuities occurring across the Robertson Lake shear zone and the Sharbot Lake mylonite zone which separate the Sharbot Lake terrane from the Elzevir and Frontenac terranes. Extensional displacements of up to 14 km are inferred between the Frontenac and Elzevir terranes of the CMB. No evidence for significant post argon-closure vertical displacement is indicated in the vicinity of the Perth Road mylonite within the Frontenac terrane. Variations of nearly 100 Ma in phlogopite 40Ar/39Ar plateau ages occur in undeformed marble on either side of the Bancroft Shear Zone. Phlogopites from sheared and mylonitized marble within the shear zone yield 40Ar/39Ar diffusional loss profiles, but have older geologically meaningless ages thought to reflect incorporation of excess argon. By ∼ 900 Ma, southeast directed extension was occurring throughout the CMB, possibly initiated along previous zones of compressional shearing. An easterly migration of active zones of extension is inferred, possibly related to an earlier, overall easterly migration of active zones of regional thrusting and easterly migration of an ancient subduction zone. The duration of extensional shearing is not well constrained, but must have ceased before ∼ 600 Ma as required by the deposition of overlying undeformed Cambrian and/or Ordovician sedimentary rocks.

Cooling and inferred uplift/erosion history of the Grenville Orogen, Ontario: Constraints from 40Ar/39Ar thermochronology

Stepwise 40Ar/39Ar degassing experiments of 57 mineral separates of hornblende, muscovite, biotite, and perthitic microcline have been used in conjunction with petrologic observations to place regional constraints on the postmetamorphic cooling and the inferred uplift and erosion history of the Grenville Orogen in Ontario. The 40Ar/39Ar data support an interpretation of slow, nearly uniform cooling (1°–4°C/m.y.) from temperatures of ˜500°C to below ˜150°C. In the Central Gneiss Belt (CGB) hornblendes cooled through Ar closure between 930 and 1025 Ma, whereas in the Central Metasedimentary Belt (CMB) hornblendes record the following range in 40Ar/39Ar cooling ages: 1104 Ma in the Frontenac terrane, 1007–1067 Ma in the Sharbot Lake terrane, 919–1026 Ma in the Elzevir terrane, and 972 Ma in the Central Metasedimentary Belt Boundary Zone. Regional uplift/erosion rates of 0.03–0.14 km/m.y. have been estimated for the Grenville Orogen in Ontario based on the 40Ar/39Ar data, a model retrograde P‐T path for rocks of the CGB, and an upper time constraint provided by flat, overlying Cambrian and Ordovician sediments. These erosion rates are consistent with rates estimated for other Proterozoic or Archean granulite terranes but are an order of magnitude slower than active orogens such as the Alps and Himalayas. A regular variation in hornblende 40Ar/39Ar cooling ages is observed in rocks that traverse highly strained often mylonitic shear zones that separate the four major terranes of the CMB. The pattern of 40Ar/39Ar ages is interpreted to reflect late‐tectonic extension, consistent with field observations in the Central Metasedimentary Belt Boundary Zone and elsewhere in the CMB. Up to 13 km of vertical displacement is inferred for some rocks in the CMB between the time they cooled below closure to argon diffusion in hornblende (˜500°C) and their exposure at the surface (˜25°C).

1.1 Ga K-rich alkaline plutonism in the SW Grenville Province

U−Pb zircon and baddeleyite dating of six syenitic stocks establishes that the ultrapotassic, potassic alkaline and shoshonitic magmatism with island-arc affinities in the Central Metasedimentary Belt (CMB) of the southwestern Grenville Province, Canada took place between 1089 and 1076 Ma, along a 400-km-long, northeast-trending plutonic belt. These ages indicate that ultrapotassic rocks with arc affinities are not unique to the Phanerozoic. West to east emplacement ages along a northern and southern cross-section of this belt range from 1083±2 Ma (Kensington), through 1081±2 Ma (Lac Rouge) to 1076 −1 +3 Ma (Loranger) in the north, and from 1089 −3 +4 Ma (loon Lake) and 1088±2 Ma (Calabogie), to 1076±2 Ma (Westport) in the south. Although closely spaced in time, in detail these ages suggest a slight younging of this magmatic activity to the southeast. Integration of the geochronological data with the spatial extent and potassic character of the plutons shows that the K-rich alkaline suite is distinct from the nepheline-syenite belt of the Bancroft terrane and from the syenite-monzonite suite of the Frontenac terrane of the CMB, and it is considered to be a magmatic episode unique to the Elzevir terrane and its Gatineau segment. The timing and the postmetamorphic emplacement of these plutons indicate that the regional greenschist to granulite-facies metamorphism of the country rock (precise age unknown) is older than 1089 Ma throughout the entire Elzevir terrane. The potassic magmatism is interpreted as the initiation of the 1090–1050 Ma Ottawan Orogeny in the Elzevir terrane; thus, the regional metamorphism in this terrane, previously assigned to the Ottawan Orogeny, is an earlier event. The contemporaneous emplacement of this postmetamorphic plutonic belt with Keweenawan volcanism is at variance with current tectonic models which consider the Keweenawan rift to be formed at the same time as regional metamorphism in the CMB.

A Model for the Formation and Crystallization of Corundum-Normative Calc-Alkaline Magmas through Amphibole Fractionation: Reply

Previous articleNext article No AccessDiscussion and ReplyA Model for the Formation and Crystallization of Corundum-Normative Calc-Alkaline Magmas through Amphibole Fractionation: ReplyR. Grant Cawthorn, and P. A. BrownR. Grant Cawthorn Search for more articles by this author , and P. A. Brown Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 86, Number 2Mar., 1978 Article DOIhttps://doi.org/10.1086/649680 Citations: 5Citations are reported from Crossref Copyright 1978 University of ChicagoPDF download Crossref reports the following articles citing this article:T A Grammatikopoulos, A H Clark, D A Archibald Petrogenesis of the Leo Lake and Lyndhurst plutons, Frontenac terrane, Central Metasedimentary Belt, southeastern Ontario, Canada, Canadian Journal of Earth Sciences 44, no.11 (Jan 2007): 107–126.https://doi.org/10.1139/e06-072 Calvin F. Miller , and Edward F. Stoddard The Role of Manganese in the Paragenesis of Magmatic Garnet: A Reply, The Journal of Geology 90, no.33 (Sep 2015): 341–343.https://doi.org/10.1086/628686 Calvin F. Miller , and Edward F. Stoddard The Role of Manganese in the Paragenesis of Magmatic Garnet: An Example from the Old Woman-Piute Range, California, The Journal of Geology 89, no.22 (Sep 2015): 233–246.https://doi.org/10.1086/628582Hugh R. Rollinson, Brian F. Windley An archaean granulite-grade tonalite-trondhjemite-granite suite from scourie, NW Scotland: Geochemistry and origin, Contributions to Mineralogy and Petrology 72, no.33 (May 1980): 265–281.https://doi.org/10.1007/BF00376145David H. Eggler Experimental igneous petrology, Reviews of Geophysics 17, no.44 (Jan 1979): 744.https://doi.org/10.1029/RG017i004p00744