Alkaline intrusions in a near-trench setting, Franciscan Complex, California: Constraints from geochemistry, petrology, and 40Ar/39Ar chronology

Mertz, D. P.; Weinrich, Andreas J.; Sharp, Warren D.; Renne, Paul R.

doi:10.2475/ajs.301.10.877

Cited by 24 publications

(15 citation statements)

References 80 publications

(87 reference statements)

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“…This low partial melt degree is consistent with the relatively high LILE contents and similar to values obtained by other authors for alkaline gabbros (e.g. Dostal and Owen, 1998;Mertz et al, 2001).…”

Section: Petrogenesissupporting

confidence: 91%

“…A simple modal batch melting model was used with the gabbro REE concentrations to constrain the degree of melting. Mineral-melt distribution coefficients and the composition of the primitive mantle source were taken from Mertz et al (2001). We plot the results in Fig.…”

Section: Petrogenesismentioning

confidence: 99%

“…Batch melting model used to approach the Bandurrias gabbro REE pattern. Primitive mantle composition, mineralogy (66% olivine, 14% orthopyroxene, 15% clinopyroxene, 5% garnet), and mineral/liquid partition coefficients are taken from Mertz et al (2001). Normalizing values are from Nakamura (1974).…”

Section: Tectonic Settingmentioning

confidence: 99%

See 2 more Smart Citations

The Bandurrias gabbro: Late Oligocene alkaline magmatism in the Patagonian Cordillera

Morata

Oliva

Cruz³

et al. 2005

Journal of South American Earth Sciences

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Section: Petrogenesissupporting

confidence: 91%

Section: Petrogenesismentioning

confidence: 99%

See 1 more Smart Citation

The Bandurrias gabbro: Late Oligocene alkaline magmatism in the Patagonian Cordillera

Morata

Oliva

Cruz³

et al. 2005

Journal of South American Earth Sciences

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“…However, several incompatible elements ratios, e.g., Sm/Zr, Ba/Nb, Nb/ U, Ba/Th, appear to vary widely for a single magma source which allows the possibility of magma mixing processes during Olmoti volcanism. Apart from magma fractionation, higher concentrations of LILE in lavas can also be achieved by a smaller degree of partial melt (Mertz et al, 2001;Johnson et al, 2005). This would seem to suggest that the trachytes were derived by small degree partial melting of underplated basalt, however this mechanism alone cannot explain the fractionation of Zr/Nb which is already accounted for through fractionation of Ti-bearing minerals, especially amphibole.…”

Section: Zr and Nb Fractionationmentioning

confidence: 90%

Petrogenesis of basalt–trachyte lavas from Olmoti Crater, Tanzania

Mollel

Swisher

McHenry

et al. 2009

Journal of African Earth Sciences

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“…The oceanic basalts in the Franciscan cannot be dated using current isotopic methods. Intrusive rocks are very rare within the Franciscan and only four small intrusions have been dated (Meyer and Naeser 1970;Mattinson and Echeverria 1980;Mertz et al 2001).…”

Section: Franciscan Geology Of Northwestern Californiamentioning

confidence: 98%

Detrital zircon U–Pb reconnaissance of the Franciscan subduction complex in northwestern California

Dumitru

Ernst

Hourigan

et al. 2015

International Geology Review

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In northwestern California, the Franciscan subduction complex has been subdivided into seven major tectonostratigraphic units. We report U-Pb ages of ≈2400 detrital zircon grains from 26 sandstone samples from 5 of these units. Here, we tabulate each unit's interpreted predominant sediment source areas and depositional age range, ordered from the oldest to the youngest unit. (1) Yolla Bolly terrane: nearby Sierra Nevada batholith (SNB); ca. 118 to 98 Ma. Rare fossils had indicated that this unit was mostly 151-137 Ma, but it is mostly much younger. (2) Central Belt: SNB; ca. 103 to 53 Ma (but poorly constrained), again mostly younger than previously thought. (3) Yager terrane: distant Idaho batholith (IB); ca. 52 to 50 Ma. Much of the Yager's detritus was shed during major core complex extension and erosion in Idaho that started 53 Ma. An Eocene Princeton River-Princeton submarine canyon system transported this detritus to the Great Valley forearc basin and thence to the Franciscan trench. (4) Coastal terrane: mostly IB, ±SNB, ±nearby Cascade arc, ±Nevada Cenozoic ignimbrite belt; 52 to <32 Ma. (5) King Range terrane: dominated by IB and SNB zircons; parts 16-14 Ma based on microfossils. Overall, some Franciscan units are younger than previously thought, making them more compatible with models for the growth of subduction complexes by progressive accretion. From ca. 118 to 70 Ma, Franciscan sediments were sourced mainly from the nearby Sierra Nevada region and were isolated from southwestern US and Mexican sources. From 53 to 49 Ma, the Franciscan was sourced from both Idaho and the Sierra Nevada. By 37-32 Ma, input from Idaho had ceased. The influx from Idaho probably reflects major tectonism in Idaho, Oregon, and Washington, plus development of a through-going Princeton River to California, rather than radical changes in the subduction system at the Franciscan trench itself.

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Alkaline intrusions in a near-trench setting, Franciscan Complex, California: Constraints from geochemistry, petrology, and 40Ar/39Ar chronology

Cited by 24 publications

References 80 publications

The Bandurrias gabbro: Late Oligocene alkaline magmatism in the Patagonian Cordillera

The Bandurrias gabbro: Late Oligocene alkaline magmatism in the Patagonian Cordillera

Petrogenesis of basalt–trachyte lavas from Olmoti Crater, Tanzania

Detrital zircon U–Pb reconnaissance of the Franciscan subduction complex in northwestern California

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