Geology and Ages of Buried Precambrian Basement Rocks, Manitoulin Island, Ontario

Schmus, W. R. Van; Card, K. D.; Harrower, K. L.

doi:10.1139/e75-107

Cited by 35 publications

(3 citation statements)

References 15 publications

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“…Loon Lake biotite granite (Dostal, 1975); 3. Manitoulin Island prophyritic quartz monzonite (adamellite), Ontario (Van Schmus, et al, 1975a); 4. Crocker Island quartz monzonite (adamellite), Ontario (Van Schmus, et al, 1975a;Card, 1965); 5, 6, 7.…”

Section: Iron-enrichmentmentioning

confidence: 99%

“…Manitoulin Island prophyritic quartz monzonite (adamellite), Ontario (Van Schmus, et al, 1975a); 4. Crocker Island quartz monzonite (adamellite), Ontario (Van Schmus, et al, 1975a;Card, 1965); 5, 6, 7. Wolf River biotite-hornblende granite (low-silica phase), Wolf River biotite granite, and Belongia biotite granite, respectively, of the Wolf River batholith.…”

Section: Iron-enrichmentmentioning

confidence: 99%

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Proterozoic anorogenic granite plutonism of North America

Anderson

1983

Geological Society of America Memoirs

411

188

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Anorogenic magnatic activity characterizes much of the late to mid-Proterozoic, from 1030 to 1770 m.y. ago, in a broad belt trending from the southwestern United States, northeastward through Labrador, across southern Greenland, and into the Baltic shield. The association of gabbroic to anorthositic rocks, a separate mangeritic series of primarily intermediate composition, and granite of definite rapakivi affinity comprise an anorogenic "trinity" of world-wide occurrence. With the exception of the 1.76 b.y. Montello batholith (Wisconsin), this episode in North America is restricted to the interval 1.0 to 1.5 b.y. and occurs in three distinct events. Over 70 percent of Proterozoic anorogenic magmatism occurs in a 1.41 to 1.49 b.y. old 600-1000 km wide belt trending from southern California to Labrador that volumetrically and age-wise is totally a North American phenomenon. Renewed anorogenic granite magmatism occurred form 1.34 to 1.41 and from 1.03 to 1.08 b.y. ago in lesser proportions. Although anorthositic and mangeritic rocks are abundant in some provinces (e.g., Labrador), rapakivi granite (in the broad usage of the term) represents by far the most abundant magma-type generated during this nonorogenic period.The modal and mineral composition of these granitic rocks is distinctive and reflects the potassic and iron-enriched character of the magmas and the unique conditions under which crystallization occurred. Principal rock types include biotite ± hornblende granite to adamellite although numerous peraluminous, two-mica (biotite + celadonitic muscovite ± garnet) granites also occur. Crystallization of these epizonal granitic magmas occurred over the range of 640 to 790° C at low total pressures (most less than 2 kb) and at relatively dry conditions. A dramatic difference in crystallization conditions lies with the level of oxygen fugacity which ranges three orders of magnitude from low (ca. QFM) to high (above Ni-NiO), resulting in systematic differences in Fe-Ti oxide mineralogy and mafic silicate composition.Compositionally, the granite magmas are subalkalic and marginally peraluminous (peralkaline varieties are rare to nonexistent). Although some hastingsite or riebeckite-bearing granites may have been derived from fractional crystallization of the mangeritic series, most are primary melts derived from fusion of lower crust material. The high potassium, Fe/Mg, Ba, and rare earth element (REE) composition of the granites is consistent with small degrees of fusion (10-30 percent) of calcalkaline crust of quartz dioritic, tonalitic, and granodioritic material. Initial Sr isotopic ratios average 0.7051 ± .0025. The relatively low ratios are the result of short residence times (commonly 170 to 340 m.y.) with much of the crustal source being formed in a preceding orogenic event. An earlier melting episode need not have occurred for the source. The dry nature of the magmas is due to vapor under-133 134 J. L. Anderson saturated melting of a metaigneous source with a total water budget less than 1 percent and tied...

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Section: Iron-enrichmentmentioning

confidence: 99%

Section: Iron-enrichmentmentioning

confidence: 99%

Proterozoic anorogenic granite plutonism of North America

Anderson

1983

Geological Society of America Memoirs

411

188

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“…Outcrops of Precambrian rocks occur in the St. Francois Mountains of southeastern Missouri (Sides, 1980;Bickford et al, 1981;Cullers et al, 1981;Sides et al, 1981), the Wolf River batholith of central Wisconsin (Anderson and Cullers, 1978), and the fel sic plutons of southern Manitoulin Island (Van Schmus et al, 1975). Inliers of 1.76 Ga rhyolite and granite in south-central Wisconsin, previously included in the Penokean orogen (Smith, 1978), have mainly A-type chemical affinities and are now known to postdate the Penokean orogeny (Smith, 1983(Smith, , 1993.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of subsurface Proterozoic rocks in the eastern Midcontinent of the United States: Further evidence for a within-plate tectonic setting

Lidiak¹

1996

Basement and Basins of Eastern North America

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Upper crustal Proterozoic rocks in the eastern Midcontinent of the UnitedStates are part of the Transcontinental Proterozoic province, a 3,000-km-long belt of mainly felsic igneous rocks that extends from western Ohio to southern Cali fornia. In the eastern Midcontinent the province consists mainly of epizonal to mesozonal granite and related rhyolite that were deposited on and emplaced within older Proterozoic rocks. New major and trace element geochemical analyses of fel sic and mafic igneous rocks in the eastern Midcontinent are presented to character ize the geologic and tectonic environment in which they formed. Felsic igneous rocks have mainly A-type chemical affinities and accumulated in a within-plate tectonic environment. Similarly, eastern Midcontinent basalts are continental within-plate tholeiites that display limited enrichment in large ion lithophile elements and light rare earth elements.The granite-rhyolite igneous suite implies magmatism associated with extension in Middle Proterozoic time. Subsequently, basaltic volcanism accompanied further extension during rifting and sedimentation. Prominent rifts include the midMichigan rift (southeast extension of the well-known Middle Proterozoic Keweenawan Midcontinent rift system), the Ft. Wayne rift, and the New Madrid rift complex (a Cambrian to possible Late Proterozoic structure that extends into the craton beneath the Mississippi embayment). Some rifts are floored by flood basalt or gabbro and are overlain by clastic sedimentary rock; others are filled only with clastic sedimentary rock. The mid-Michigan and the Ft. Wayne rifts are characterized by elongate arrays of positive magnetic and gravity anomalies, attesting to thick accu mulations of mafic igneous rocks. In contrast, because prominent potential field anomalies occur only along the margins of the New Madrid rift complex, this fea ture may contain mainly sedimentary rock and only minor basalt. The Middle Run structure in southwestern Ohio and adjacent Indiana is not associated with regional gravity or magnetic anomalies and is apparently filled with Middle or Late Protero zoic or younger sedimentary rock. Other prominent anomalies occur within the granite-rhyolite terrane: these include widespread, large (10-20 km diameter), high-amplitude (600-700 gamma) circular to elliptical positive magnetic anomalies that are associated with magnetite-series granite. Detailed magnetic studies of the Spavinaw, Oklahoma, granite reveal that the enhanced magnetization is attribut able to two generations of magnetite.

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Geology of the Precambrian Basement Beneath the Paleozoic of Southwestern Ontario

Easton

Carter²

1995

Basement Tectonics 10

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Geology and Ages of Buried Precambrian Basement Rocks, Manitoulin Island, Ontario

Cited by 35 publications

References 15 publications

Proterozoic anorogenic granite plutonism of North America

Proterozoic anorogenic granite plutonism of North America

Geochemistry of subsurface Proterozoic rocks in the eastern Midcontinent of the United States: Further evidence for a within-plate tectonic setting

Geology of the Precambrian Basement Beneath the Paleozoic of Southwestern Ontario

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