The fine gold intrusive suite: The roles of basement terranes and magma source development in the early Cretaceous Sierra Nevada batholith

Jade Star Lackey, M. Robinson Cecil, Cameron J. Windham, Ryan E. Frazer, Ilya N. Bindeman, George E Gehrels

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The Fine Gold Intrusive Suite is one of the largest (>2000 km2) and oldest intrusive complexes in the Sierra Nevada batholith (California, USA), and therefore contains a wealth of information about nascent magmatic processes in a convergent margin arc. Because the suite intrudes both accreted oceanic and/or island-arc terranes and continental crust, it provides perspective on how convergent margin magmatism recycles existing crust versus reworking of fringing island arcs into continental crust. Such insight informs our understanding of how continental crust formation may have operated in the Phanerozoic as compared to earlier in Earth history. New zircon U-Pb geochronology shows that the largely tonalitic suite was emplaced over ~19 m.y. (124-105 Ma), in three pulses that young from west to east. The most recent domain is nested within the previous ones, such that lobes of magma protruding from the main bodies of the Bass Lake Tonalite (the primary member of the Fine Gold Intrusive Suite) are older than interior areas. Zircon δ18O (6.1‰-8.0‰) and εHf (-4.7 + 6.4) show temporal trends indicating that early magmas were source mixtures of mantle with as much as 45% Paleozoic to Mesozoic oceanic and/or arc rocks, whereas later magmas contain greater inputs (to 50%) of Proterozoic North American crust. Older domains in the suite were likely generated from isolated sources, including initial high Sr/Y (to ~90), high Na2O magmas consistent with garnetbearing sources inferred to be relatively deep. Higher 87Sr/86Sr, lower εHf, and higher Rb/Sr values in younger plutons show a source that tapped greater proportions of North American crust and was presumably more organized and larger, given its more homogeneous isotopic and trace element traits. Our findings also show that expression of the 87Sr/86Sr = 0.706 isopleth in arc magmas may be delayed until magma sources are sufficiently vigorous to melt and incorporate aged continental crust. Therefore, Sri values of older stitching plutons may better record the position of discrete terrane boundaries, whereas younger plutons will record the magmatically average position of terrane boundaries. Although the Fine Gold Intrusive Suite is comparable to the Late Cretaceous voluminous intrusive suite of eastern Sierran suites in terms of duration and age zoning of magmatism, the influence of preexisting basement compositions and differing degrees of organization of the magma sources with age is more pronounced. In addition, the findings show that recycling of fringing arc terranes into continental crust is relatively rapid and that estimates of the growth of Phanerozoic continental crust from such reprocessing should be revised upward.

Original languageEnglish (US)
Pages (from-to)292-313
Number of pages22
JournalGeosphere
Volume8
Issue number2
DOIs
StatePublished - 2012

Fingerprint

batholith
continental crust
terrane
gold
magma
Cretaceous
pluton
convergent margin
crust
Phanerozoic
island arc
magmatism
zircon
tonalite
reworking
geochronology
zoning
Proterozoic
recycling
Paleozoic

ASJC Scopus subject areas

  • Geology
  • Stratigraphy

Cite this

The fine gold intrusive suite : The roles of basement terranes and magma source development in the early Cretaceous Sierra Nevada batholith. / Lackey, Jade Star; Robinson Cecil, M.; Windham, Cameron J.; Frazer, Ryan E.; Bindeman, Ilya N.; Gehrels, George E.

In: Geosphere, Vol. 8, No. 2, 2012, p. 292-313.

Research output: Contribution to journalArticle

Lackey, Jade Star ; Robinson Cecil, M. ; Windham, Cameron J. ; Frazer, Ryan E. ; Bindeman, Ilya N. ; Gehrels, George E. / The fine gold intrusive suite : The roles of basement terranes and magma source development in the early Cretaceous Sierra Nevada batholith. In: Geosphere. 2012 ; Vol. 8, No. 2. pp. 292-313.
@article{dab4c507c7764ee0aea587f36bd916da,
title = "The fine gold intrusive suite: The roles of basement terranes and magma source development in the early Cretaceous Sierra Nevada batholith",
abstract = "The Fine Gold Intrusive Suite is one of the largest (>2000 km2) and oldest intrusive complexes in the Sierra Nevada batholith (California, USA), and therefore contains a wealth of information about nascent magmatic processes in a convergent margin arc. Because the suite intrudes both accreted oceanic and/or island-arc terranes and continental crust, it provides perspective on how convergent margin magmatism recycles existing crust versus reworking of fringing island arcs into continental crust. Such insight informs our understanding of how continental crust formation may have operated in the Phanerozoic as compared to earlier in Earth history. New zircon U-Pb geochronology shows that the largely tonalitic suite was emplaced over ~19 m.y. (124-105 Ma), in three pulses that young from west to east. The most recent domain is nested within the previous ones, such that lobes of magma protruding from the main bodies of the Bass Lake Tonalite (the primary member of the Fine Gold Intrusive Suite) are older than interior areas. Zircon δ18O (6.1‰-8.0‰) and εHf (-4.7 + 6.4) show temporal trends indicating that early magmas were source mixtures of mantle with as much as 45{\%} Paleozoic to Mesozoic oceanic and/or arc rocks, whereas later magmas contain greater inputs (to 50{\%}) of Proterozoic North American crust. Older domains in the suite were likely generated from isolated sources, including initial high Sr/Y (to ~90), high Na2O magmas consistent with garnetbearing sources inferred to be relatively deep. Higher 87Sr/86Sr, lower εHf, and higher Rb/Sr values in younger plutons show a source that tapped greater proportions of North American crust and was presumably more organized and larger, given its more homogeneous isotopic and trace element traits. Our findings also show that expression of the 87Sr/86Sr = 0.706 isopleth in arc magmas may be delayed until magma sources are sufficiently vigorous to melt and incorporate aged continental crust. Therefore, Sri values of older stitching plutons may better record the position of discrete terrane boundaries, whereas younger plutons will record the magmatically average position of terrane boundaries. Although the Fine Gold Intrusive Suite is comparable to the Late Cretaceous voluminous intrusive suite of eastern Sierran suites in terms of duration and age zoning of magmatism, the influence of preexisting basement compositions and differing degrees of organization of the magma sources with age is more pronounced. In addition, the findings show that recycling of fringing arc terranes into continental crust is relatively rapid and that estimates of the growth of Phanerozoic continental crust from such reprocessing should be revised upward.",
author = "Lackey, {Jade Star} and {Robinson Cecil}, M. and Windham, {Cameron J.} and Frazer, {Ryan E.} and Bindeman, {Ilya N.} and Gehrels, {George E}",
year = "2012",
doi = "10.1130/GES00745.1",
language = "English (US)",
volume = "8",
pages = "292--313",
journal = "Geosphere",
issn = "1553-040X",
publisher = "Geological Society of America",
number = "2",

}

TY - JOUR

T1 - The fine gold intrusive suite

T2 - The roles of basement terranes and magma source development in the early Cretaceous Sierra Nevada batholith

AU - Lackey, Jade Star

AU - Robinson Cecil, M.

AU - Windham, Cameron J.

AU - Frazer, Ryan E.

AU - Bindeman, Ilya N.

AU - Gehrels, George E

PY - 2012

Y1 - 2012

N2 - The Fine Gold Intrusive Suite is one of the largest (>2000 km2) and oldest intrusive complexes in the Sierra Nevada batholith (California, USA), and therefore contains a wealth of information about nascent magmatic processes in a convergent margin arc. Because the suite intrudes both accreted oceanic and/or island-arc terranes and continental crust, it provides perspective on how convergent margin magmatism recycles existing crust versus reworking of fringing island arcs into continental crust. Such insight informs our understanding of how continental crust formation may have operated in the Phanerozoic as compared to earlier in Earth history. New zircon U-Pb geochronology shows that the largely tonalitic suite was emplaced over ~19 m.y. (124-105 Ma), in three pulses that young from west to east. The most recent domain is nested within the previous ones, such that lobes of magma protruding from the main bodies of the Bass Lake Tonalite (the primary member of the Fine Gold Intrusive Suite) are older than interior areas. Zircon δ18O (6.1‰-8.0‰) and εHf (-4.7 + 6.4) show temporal trends indicating that early magmas were source mixtures of mantle with as much as 45% Paleozoic to Mesozoic oceanic and/or arc rocks, whereas later magmas contain greater inputs (to 50%) of Proterozoic North American crust. Older domains in the suite were likely generated from isolated sources, including initial high Sr/Y (to ~90), high Na2O magmas consistent with garnetbearing sources inferred to be relatively deep. Higher 87Sr/86Sr, lower εHf, and higher Rb/Sr values in younger plutons show a source that tapped greater proportions of North American crust and was presumably more organized and larger, given its more homogeneous isotopic and trace element traits. Our findings also show that expression of the 87Sr/86Sr = 0.706 isopleth in arc magmas may be delayed until magma sources are sufficiently vigorous to melt and incorporate aged continental crust. Therefore, Sri values of older stitching plutons may better record the position of discrete terrane boundaries, whereas younger plutons will record the magmatically average position of terrane boundaries. Although the Fine Gold Intrusive Suite is comparable to the Late Cretaceous voluminous intrusive suite of eastern Sierran suites in terms of duration and age zoning of magmatism, the influence of preexisting basement compositions and differing degrees of organization of the magma sources with age is more pronounced. In addition, the findings show that recycling of fringing arc terranes into continental crust is relatively rapid and that estimates of the growth of Phanerozoic continental crust from such reprocessing should be revised upward.

AB - The Fine Gold Intrusive Suite is one of the largest (>2000 km2) and oldest intrusive complexes in the Sierra Nevada batholith (California, USA), and therefore contains a wealth of information about nascent magmatic processes in a convergent margin arc. Because the suite intrudes both accreted oceanic and/or island-arc terranes and continental crust, it provides perspective on how convergent margin magmatism recycles existing crust versus reworking of fringing island arcs into continental crust. Such insight informs our understanding of how continental crust formation may have operated in the Phanerozoic as compared to earlier in Earth history. New zircon U-Pb geochronology shows that the largely tonalitic suite was emplaced over ~19 m.y. (124-105 Ma), in three pulses that young from west to east. The most recent domain is nested within the previous ones, such that lobes of magma protruding from the main bodies of the Bass Lake Tonalite (the primary member of the Fine Gold Intrusive Suite) are older than interior areas. Zircon δ18O (6.1‰-8.0‰) and εHf (-4.7 + 6.4) show temporal trends indicating that early magmas were source mixtures of mantle with as much as 45% Paleozoic to Mesozoic oceanic and/or arc rocks, whereas later magmas contain greater inputs (to 50%) of Proterozoic North American crust. Older domains in the suite were likely generated from isolated sources, including initial high Sr/Y (to ~90), high Na2O magmas consistent with garnetbearing sources inferred to be relatively deep. Higher 87Sr/86Sr, lower εHf, and higher Rb/Sr values in younger plutons show a source that tapped greater proportions of North American crust and was presumably more organized and larger, given its more homogeneous isotopic and trace element traits. Our findings also show that expression of the 87Sr/86Sr = 0.706 isopleth in arc magmas may be delayed until magma sources are sufficiently vigorous to melt and incorporate aged continental crust. Therefore, Sri values of older stitching plutons may better record the position of discrete terrane boundaries, whereas younger plutons will record the magmatically average position of terrane boundaries. Although the Fine Gold Intrusive Suite is comparable to the Late Cretaceous voluminous intrusive suite of eastern Sierran suites in terms of duration and age zoning of magmatism, the influence of preexisting basement compositions and differing degrees of organization of the magma sources with age is more pronounced. In addition, the findings show that recycling of fringing arc terranes into continental crust is relatively rapid and that estimates of the growth of Phanerozoic continental crust from such reprocessing should be revised upward.

UR - http://www.scopus.com/inward/record.url?scp=84862596664&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84862596664&partnerID=8YFLogxK

U2 - 10.1130/GES00745.1

DO - 10.1130/GES00745.1

M3 - Article

AN - SCOPUS:84862596664

VL - 8

SP - 292

EP - 313

JO - Geosphere

JF - Geosphere

SN - 1553-040X

IS - 2

ER -