Trondhjemite Batholith Near Bidwell Bar, California

Compton, Robert R.

doi:10.1130/0016-7606(1955)66[9:tbnbbc]2.0.co;2

Cited by 57 publications

(31 citation statements)

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“…Paterson & Fowler (1993) considered stoping to be an important material transfer process, in agreement with other researchers who considered it a valid emplacement mechanism (e.g. Compton 1955;Snowden & Snowden 1981;Marsh 1982;Galadí-Enríquez et al 2003;Burchardt et al 2009Burchardt et al , 2012. Recently, Leake (2011) also cited stoping as a major process during the emplacement of the Roundstone Pluton.…”

Section: An Emplacement Model For the Roundstone Plutonsupporting

confidence: 67%

Distinguishing diapirs from inflated plutons: an integrated rock magnetic fabric and structural study on the Roundstone Pluton, western Ireland

McCarthy

Petronis

Reavy

et al. 2015

JGS

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Granitoid plutons account for much of the continental crust and are critical in the generation of several economic resources. Despite over a century of research, the fundamental process by which large felsic bodies intrude remains controversial. Two contrasting models persist: (1) mass ascent and subsequent cooling of magma (diapirism); (2) sheet ascent and subsequent emplacement (laccoliths). The latter hypothesis is different from the former as distinct ascent and emplacement processes must occur and be identifiable; traditional field methods rarely allow this important distinction to be made. We present field, petrographic and anisotropy of magnetic susceptibility data from the Roundstone Pluton, Connemara, western Ireland, which was previously considered a diapiric intrusion. The new data reveal anomalous subvertical magmatic lineations in the core of this circular intrusion as well as a suite of magmatic and submagmatic fabrics that parallel NNW-SSE country rock faults and coeval G2 sheets within the pluton. We deduce that these structures reflect a distinct centralized ascent process along a NNW-SSE conduit. Lateral emplacement and pluton inflation followed, ultimately forming a punched laccolith. We conclude that the combined application of the above techniques provides a unique insight into pluton architecture that removes ambiguity between contrasting diapiric and inflated pluton models.Supplementary material: Complete rock magnetic data tables and sample site coordinates (Irish Grid) are available at

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Section: An Emplacement Model For the Roundstone Plutonsupporting

confidence: 67%

Distinguishing diapirs from inflated plutons: an integrated rock magnetic fabric and structural study on the Roundstone Pluton, western Ireland

McCarthy

Petronis

Reavy

et al. 2015

JGS

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“…Most of the data are for the Merrimac (Hietanen, 1951) and Bald Rock (Compton, 1955;Larsen and Poldervaart, 1961) plutons at the north end of the western Sierra belt. Data for the small Rocky Hill stock in the southern part of the western Sierra belt are also available from a study by Putnam and Alfors (1965).…”

Section: Comparison With Plutons Of the Western Sierra Nevadamentioning

confidence: 99%

“…The data fall predominantly in the quartz diorite and granodiorite fields. The trondhjemitic character of plutons in the northwestern Sierra Nevada was observed (Hietanen, 1951;Compton, 1955;Larsen and Poldervaart, 1961) before trondhjemites were recognized in the Klamath Mountains.…”

Section: Comparison With Plutons Of the Western Sierra Nevadamentioning

confidence: 99%

Plutonic rocks of the Klamath Mountains, California and Oregon

Hotz¹

1971

Professional Paper

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“…Compton 1955;Bykerk-Kauffman 1990;Stein 1994), but commonly remain hard to document because of the difficulty in clearly tying brittle structures in the outer parts of aureoles to emplacement. Our work in progress also suggests that it may be common to have both brittle (e.g.…”

Section: Shallow To Mid-crustal Systemsmentioning

confidence: 99%

Pluton emplacement in arcs: a crustal-scale exchange process

Paterson

Fowler

Miller

1996

The Third Hutton Symposium on the Origin of Granites and Related Rocks

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Buddington (1959) pointed out that the construction of large crustal magma chambers involves complex internal processes as well as multiple country rock material transfer processes (MTPs), which reflect large horizontal, vertical and temporal gradients in physical conditions. Thus, we have attempted to determine the relative importance of different magmatic and country rock MTPs at various crustal depths, and whether country rock MTPs largely transport material vertically or horizontally, rather than seeking a single model of magma ascent and emplacement.Partially preserved roofs of nine plutons and in some cases roof-wall transitions with roof emplacement depths of 1-5-11 km were mapped. During emplacement, these roofs were not deformed in a ductile manner, detached or extended by faults, or significantly uplifted. Instead, sharp, irregular, discordant contacts are the rule with sloped blocks often preserved immediately below the roof, even at depths of 10 km. The upper portions of these magma chambers are varied, sometimes preserving the crests of more evolved magmas or local zones of volatile-rich phases and complex zones of dyking and magma mingling. Magmatic structures near roofs display a wide variety of patterns and generally formed after emplacement. Transitions from gently dipping roofs to steep walls are abrupt. At shallow crustal levels, steep wall contacts have sharp, discordant, stepped patterns with locally preserved sloped blocks indicating that the chamber grew sideways in part by sloping. Around deeper plulons, an abrupl transition (sometimes within hundreds of metres) occurs in the counlry rock from discordanl, brittle roofs to moderately concordanl, walls deformed in a ductile manner defining narrow structural aureoles. Brittle or ductile faults are not present at roof-wall joins.Near steep wall contacts at shallow to mid-crustal deplhs (5-15 km), vertical and horizonlal deflections of pre-emplacement markers (e.g. bedding, faults, dykes), and ductile slrains in narrow aureoles (0-1-0-3 body radii) give a complele range of bulk strain values lhal account for 0-100% of the needed space, but average around 30%, or less, particularly for larger balholilhs. A lack of far-field deflection of these same markers rules out significant horizontal displacement outside Ihe aureoles and requires lhat any near-field lateral shorlening is accommodaled by vertical flow. Lateral variations from ductile (inner aureole) to brittle (outer aureole) MTPs are lypically observed. Compositional zoning is widespread wilhin Ihese magma bodies and is Ihoughl lo represent separately evolved pulses lhal Iravelled up the same magma plumbing system. Magmatic foliations and linealions commonly cross-cut conlacts belween pulses and reflecl the slrain caused eilher by Ihe late flow of melt or regional deformation.Country rocks near the few examined mid-to deep crustal walls (10-30 km) are extensively deformed, with both discordant and concordant contacts present; however, the distinction between regional and emplacement-relate...

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Trondhjemite Batholith Near Bidwell Bar, California

Cited by 57 publications

References 0 publications

Distinguishing diapirs from inflated plutons: an integrated rock magnetic fabric and structural study on the Roundstone Pluton, western Ireland

Distinguishing diapirs from inflated plutons: an integrated rock magnetic fabric and structural study on the Roundstone Pluton, western Ireland

Plutonic rocks of the Klamath Mountains, California and Oregon

Pluton emplacement in arcs: a crustal-scale exchange process

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