Juan de Fuca Ridge atlas, SeaMARC II acoustic imagery

Davis, Earl E.; Currie, RG; Sawyer, B; Hussong, D. M.

doi:10.4095/293603

Cited by 11 publications

(4 citation statements)

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“…Extensive hydrothermal deposits and extinct sulfide chimneys along the rift valley were discovered on previous SER mapping expeditions [ Davis et al ., ; Scott et al ., ]. Hydrothermal activity in the rift valley appears to have been locally extensive in the past.…”

Section: Geological and Petrological Settingmentioning

confidence: 99%

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Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography

Deschamps

Tivey

Chadwick

et al. 2013

Geochem Geophys Geosyst

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[1] We combine high-resolution bathymetry acquired using the Autonomous Underwater Vehicle ABE with digital seafloor imagery collected using the remotely operated vehicle ROPOS across the axial valley of the Southern Explorer Ridge (SER) to infer the recent volcanic and tectonic processes. The SER is an intermediate spreading ridge located in the northeast Pacific. It hosts the Magic Mountain hydrothermal vent. We reconstruct the unfaulted seafloor terrain at SER based on calculations of the vertical displacement field and fault parameters. The vertical changes between the initial and the restored topographies reflect the integrated effects of volcanism and tectonism on relief-forming processes over the last 11,000-14,000 years. The restored topography indicates that the axial morphology evolved from a smooth constructional dome >500 m in diameter, to a fault-bounded graben,~500 m wide and 30-70 m deep. This evolution has been accompanied by changes in eruptive rate, with deposition of voluminous lobate and sheet flows when the SER had a domed morphology, and limited-extent low-effusion rate pillow eruptions during graben development. Most of the faults shaping the present axial valley postdate the construction of the dome. Our study supports a model of cyclic volcanism at the SER with periods of effusive eruptions flooding the axial rift, centered on the broad plateau at the summit of the ridge, followed by a decrease in eruptive activity and a subsequent dominance of tectonic processes, with minor low-effusion rate eruptions confined to the axial graben. The asymmetric shape of the axial graben supports an increasing role of extensional processes, with a component of simple shear in the spreading processes.Components: 9,800 words, 8 figures.

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Section: Geological and Petrological Settingmentioning

confidence: 99%

“…Bathymetry of the SER summit with the distribution of the lava morphologies from SeaMARC I side‐scan sonar imagery [ Davis et al ., ; Scott et al . ] and visual observations during ROPOS dive R665 (track indicated in black, see Figure ).…”

Section: Lava Morphology and Relation With Tectonic Structuresmentioning

confidence: 99%

Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography

Deschamps

Tivey

Chadwick

et al. 2013

Geochem Geophys Geosyst

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“…The valley floor slopes gently down toward the base of an up to 250-m-high normal-fault scarp that forms the eastern boundary of the valley. This fault cuts an extensive volcanic surface that appears to be of relatively uniform age in both 12-and 30-kHz acoustic imagery (Davis et al, 1984;Fig. 2C).…”

Section: Endeavour Valleymentioning

confidence: 99%

“…In this paper we present compilations of SeaBeam bathymetry, SeaMARC II and I acoustic imagery, seismic reflection profiles, and detailed heat flow measurements collected during a series of cruises to the southern part of Middle Valley from 1983 to 1989, and discuss the implications of these data regarding the nature of hydrothermal circulation and discharge in this sedimented rift. Some of the regional data have been published previously (e.g., Karsten et al, 1986;Davis et al, 1984Davis et al, , 1986Davis, Goodfellow, et al, 1987), and the details of the data acquisition can be found in those references. New data include multichannel seismic reflection profiles and heat flow determinations; the details of acquisition and processing of these data are described in Rohr et al (1992) and in this paper.…”

Section: Introductionmentioning

confidence: 99%

Tectonic and Thermal Structure of the Middle Valley Sedimented Rift, Northern Juan de Fuca Ridge

Davis¹,

Villinger²

1992

Proceedings of the Ocean Drilling Program

162

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Recently acquired single-and multichannel seismic reflection profiles and over 500 heat flow measurements augment SeaBeam bathymetric and SeaMARC II and I side-scan acoustic data to provide new constraints on the tectonic setting and thermal structure of the sediment-filled rift, Middle Valley, of the northern Juan de Fuca Ridge. Over most of the length of the Juan de Fuca Ridge, spreading takes place along high-standing volcanic ridges, which are broken only by relatively small axial rift grabens. Near the northern end of the ridge south of the Sovanco fracture zone intersection, the volcanic supply is diminished, probably because of the lateral heat loss at the end of the ridge and the northern migration of the ridge in the wake of the lithospheric Explorer plate. This has resulted in the formation of deep rift valleys at the spreading axis. The deepest of these, Middle Valley, has been buried syntectonically by Pleistocene turbidite sediment. Heat flow in this valley varies inversely with sediment thickness, suggesting that the sediment forms a hydrologic seal over permeable igneous crust, where efficient hydrothermal circulation maintains relatively uniform temperatures. This simple model is investigated by comparing directly the thermal regime at depth and the seismic structure of the valley. Temperatures at depth are estimated from seafloor heat flow measurements using sediment physical properties derived from multichannel seismic (MCS) velocities. Although it is transitional and poorly defined in places, the acoustically defined sediment-basement contact is estimated to be typically about 300° C. Numerous local heat flow anomalies are observed in the valley. Two are associated with known hydrothermal vents also of roughly 300° C. Another lies near the normal-fault scarp that forms the eastern boundary of the valley, where basement is exposed at the seafloor, although in general, heat flow in the vicinity of the fault is relatively low, as are estimated basement temperatures. This suggests that the fault and the exposure of basement may serve primarily as a conduit for diffuse recharge of crustal fluids. Other heat flow anomalies and associated vents or vent fields overlie buried basement edifices where the sediment cover is locally attenuated. There is no significant heat flow anomaly and apparently no hydrothermal discharge associated with the most recent (Holocene) intrusive activity in the valley. The location of hydrothermal upflow zones appears to be influenced more by permeability structure, which is inferred to be controlled primarily by basement topography and variations in sediment thickness, rather than by the location of heat sources. The generally continuous, low-permeability sediment cover allows local vents to tap large areas of high-temperature permeable crust. The 300° C hydrothermal fluid temperatures currently present in Middle Valley are low compared to those required to produce solutions of high metal concentration. The presence of base-metal sulfide deposits in the valley suggests eith...

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Mixing of magmas from enriched and depleted mantle sources in the northeast Pacific: West Valley segment, Juan de Fuca Ridge

Cousens

Allan²,

Leybourne

et al. 1995

Contr. Mineral. and Petrol.

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Juan de Fuca Ridge atlas, SeaMARC II acoustic imagery

Cited by 11 publications

References 0 publications

Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography

Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography

Tectonic and Thermal Structure of the Middle Valley Sedimented Rift, Northern Juan de Fuca Ridge

Mixing of magmas from enriched and depleted mantle sources in the northeast Pacific: West Valley segment, Juan de Fuca Ridge

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