Spatial and Temporal Scale of Mantle Enrichment at the Endeavour Segment, Juan de Fuca Ridge

Gill, James B.; Michael, Peter J.; Woodcock, J.; Dreyer, B. M.; Ramos, Frank C.; Clague, David A.; Kela, J.; Scott, Steve; Konrad, Kevin; Stakes, Debra S.

doi:10.1093/petrology/egw024

Cited by 25 publications

(42 citation statements)

References 115 publications

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“…The decrease in ε Nd with increase in [La/Gd](n) suggests incorporation of isotopically enriched source mantle with increasing LREE (i.e., an E‐MORB component). This relation is widespread in MORs world‐side and reflects incorporation of recycled material in the source in many cases [ Douglass et al ., ; Fontignie and Schilling , ; Gill et al ., ; Ingle et al ., ; Regelous et al ., ; Schilling , ]. Such correlations disappear at [La/Gd](n) < 0.59 (Figure a, inset), which is the value we used as our cutoff to isolate isotopically and elementally depleted DMM and D‐DMM source mantles.…”

Section: Isotopic Evolution Of the Depleted Mantle (Dmm And D‐dmm)mentioning

confidence: 97%

“…In these calculations, parameters governing melting ( T p , P mt , F , and the fraction of PM and DMM in the source mantle f PM and f DMM ) are calculated as the fitting parameters in an inversion model using Monte Carlo calculations (Appendix and Kimura and Kawabata []). No pyroxenite fraction ( f PY ) is needed in the mantle source of N‐ to D‐MORB‐like compositions, unlike fits to OIB or LREE‐enriched E‐MORB [ Gill et al ., ; Kimura and Kawabata , ; Sobolev et al ., ].…”

Section: Mantle Potential Temperature and Compositionmentioning

confidence: 99%

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Origin of geochemical mantle components: Role of spreading ridges and thermal evolution of mantle

Kimura

Gill

Keken

et al. 2017

Geochem Geophys Geosyst

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We explore the element redistribution at mid-ocean ridges (MOR) using a numerical model to evaluate the role of decompression melting of the mantle in Earth's geochemical cycle, with focus on the formation of the depleted mantle component. Our model uses a trace element mass balance based on an internally consistent thermodynamic-petrologic computation to explain the composition of MOR basalt (MORB) and residual peridotite. Model results for MORB-like basalts from 3.5 to 0 Ga indicate a high mantle potential temperature (T p ) of 1650-15008C during 3.5-1.5 Ga before decreasing gradually to 13008C today. The source mantle composition changed from primitive (PM) to depleted as T p decreased, but this source mantle is variable with an early depleted reservoir (EDR) mantle periodically present. We examine a twostage Sr-Nd-Hf-Pb isotopic evolution of mantle residues from melting of PM or EDR at MORs. At high-T p (3.5-1.5 Ga), the MOR process formed extremely depleted DMM. This coincided with formation of the majority of the continental crust, the subcontinental lithospheric mantle, and the enriched mantle components formed at subduction zones and now found in OIB. During cooler mantle conditions (1.5-0 Ga), the MOR process formed most of the modern ocean basin DMM. Changes in the mode of mantle convection from vigorous deep mantle recharge before 1.5 Ga to less vigorous afterward is suggested to explain the thermochemical mantle evolution.

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Section: Isotopic Evolution Of the Depleted Mantle (Dmm And D‐dmm)mentioning

confidence: 97%

Section: Mantle Potential Temperature and Compositionmentioning

confidence: 99%

Origin of geochemical mantle components: Role of spreading ridges and thermal evolution of mantle

Kimura

Gill

Keken

et al. 2017

Geochem Geophys Geosyst

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“…MORB recovered from the neovolcanic zone are variable compared to other NE Pacific ridge segments ranging from near-primary melts with Mg# (100Mg/(0.85Fe + Mg) of 68 (8.8% MgO) to melts that have Mg# as low as 57 (MgO as low as 6.9%). Endeavor Segment lavas are even more variable in degree of fractionation and enrichment (Gill et al, 2016), The North Gorda magmas underwent between ∼4% and ∼40-45% crystal fractionation, based on simple enrichment factors of incompatible elements. Likewise, the lavas range in K 2 O/TiO 2 from 0.06 to 0.15 and so from N-MORB to T-MORB.…”

Section: Variations Along Axis In the Axial Grabenmentioning

confidence: 99%

“…The limited sampling of off-axis, older, lavas at North Gorda have a much narrower compositional range. Endeavor segment also has a wide range of lava compositions (Gill et al, 2016) and few channelized flows within the axial graben, erupted while the magma supply was low. Flank lavas, erupted when the segment was in a high-volume magmatic phase, are more compositionally homogeneous (Clague et al, 2014).…”

Section: The North Gorda Segment Compared With Other Pacific Intermedmentioning

confidence: 99%

Lava Flows Erupted in 1996 on North Gorda Ridge Segment and the Geology of the Nearby Sea Cliff Hydrothermal Vent Field From 1-M Resolution AUV Mapping

et al. 2020

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The northernmost segment of the Gorda mid-ocean ridge is the site of a smallvolume eruption in 1996 and the persistent off-axis Sea Cliff hydrothermal vent field. To better understand the geologic setting and formation of these features, 1-m resolution bathymetric mapping using autonomous underwater vehicles was completed in 2016. The mapped region covers 35 km 2 and 15.6 km of the volcanic axis from south of the 1996 lava flows, and a cross section for ∼4.5 km perpendicular to the axis, that extends beyond the Sea Cliff hydrothermal vent field. A proposed 1996 flow ∼7 km south of previously mapped flows is an artifact from a poor pre-eruption survey. The 1996 flows consist of three discrete steep hummocky mounds of pillows and syneruptive talus. The Sea Cliff hydrothermal field is located a few km north of the narrowest, shallowest section of the ridge segment, 2.6 km east of the center of the neovolcanic zone, and ∼370 m above the average depth of the axial graben on the largest offset ridge-parallel fault. No evidence supports the prior hypothesis that the site is located where two fault systems intersect. The axial graben is asymmetrical with larger fault offsets on the east side. The ridge axis below the hydrothermal field and to the south toward the 1996 flows is constructed dominantly of hummocky flows of pillow basalt, many unusually steep-sided, with syneruptive talus at the base of their steep slopes. Three channelized flows ponded between steep hummocky flows, and then partially drained. Some loweruption-rate hummocky flows and high-eruption-rate channelized flows have nearly identical compositions, supporting the idea that eruption rates on mid-ocean ridges vary because of different dike widths. Four volcanic structures with volumes between 0.18 and 0.25 km 3 occur in the axial graben south of the 1996 flows. Two are flat-topped cones, another is a 1.5-km diameter inflated hummocky flow with 7 pit craters that demonstrate that the flow had a molten interior during growth. The fourth voluminous structure is a steep ridge with abundant syneruptive talus on its lower slopes. The North Gorda segment is an end-member, structurally and volcanically, compared with other Pacific intermediate-rate spreading ridges.

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“…The Gorda plate, which is subducted beneath the California portion of the arc, has a more depleted MORB composition than that of the Juan de Fuca plate (Davis et al, 2008;Gill et al, 2016). The Gorda plate and the northernmost portion of the Juan de Fuca plate are more intensely fractured, which may introduce more subduction fluid to the mantle wedge beneath the northern and southern portions of the arc than the central arc (Schmidt et al, 2008).…”

Section: Subducted Slab Compositionmentioning

confidence: 99%

Statistics and segmentation: Using Big Data to assess Cascades arc compositional variability

Pitcher

Kent

2019

Geochimica et Cosmochimica Acta

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Spatial and Temporal Scale of Mantle Enrichment at the Endeavour Segment, Juan de Fuca Ridge

Cited by 25 publications

References 115 publications

Origin of geochemical mantle components: Role of spreading ridges and thermal evolution of mantle

Origin of geochemical mantle components: Role of spreading ridges and thermal evolution of mantle

Lava Flows Erupted in 1996 on North Gorda Ridge Segment and the Geology of the Nearby Sea Cliff Hydrothermal Vent Field From 1-M Resolution AUV Mapping

Statistics and segmentation: Using Big Data to assess Cascades arc compositional variability

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