@article {ISI:000345545100011,
	title = {{The Anatomy of a Buried Submarine Hydrothermal System, Clark Volcano, Kermadec Arc, New Zealand}},
	journal = {ECONOMIC GEOLOGY},
	volume = {109},
	number = {8},
	year = {2014},
	month = {dec},
	pages = {2261{\textendash}2292},
	type = {Article},
	abstract = {Clark volcano of the Kermadec arc, northeast of New Zealand, is a large stratovolcano comprised of two coalescing volcanic cones; an apparently younger, more coherent, twin-peaked edifice to the northwest and a relatively older, more degraded and tectonized cone to the southeast. High-resolution water column surveys show an active hydrothermal system at the summit of the NW cone largely along a ridge spur connecting the two peaks, with activity also noted at the head of scarps related to sector collapse. Clark is the only known cone volcano along the Kermadec arc to host sulfide mineralization. Volcano-scale gravity and magnetic surveys over Clark show that it is highly magnetized, and that a strong gravity gradient exists between the two edifices. Modeling suggests that a crustal-scale fault lies between these two edifices, with thinner crust beneath the NW cone. Locations of regional earthquake epicenters show a southwest-northeast trend bisecting the two Clark cones, striking northeastward into Tangaroa volcano. Detailed mapping of magnetics above the NW cone summit shows a highly magnetized ring structure 350 m below the summit that is not apparent in the bathymetry; we believe this structure represents the top of a caldera. Oblate zones of low (weak) magnetization caused by hydrothermal fluid upflow, here termed burn holes, form a pattern in the regional magnetization resembling Swiss cheese. Presumably older burn holes occupy the inner margin of the ring structure and show no signs of hydrothermal activity, while younger burn holes are coincident with active venting on the summit. A combination of mineralogy, geochemistry, and seafloor mapping of the NW cone shows that hydrothermal activity today is largely manifest by widespread diffuse venting, with temperatures ranging between 56 degrees and 106 degrees C. Numerous, small ({\textless}= 30 cm high) chimneys populate the summit area, with one site host to the similar to 7-m-tall {\textquoteleft}{\textquoteleft}Twin Towers{\{}{\textquoteright}{\textquoteright}{\}} chimneys with maximum vent fluid temperatures of 221 degrees C (pH 4.9), consistent with delta S-34(anhydrite-pyrite) values indicating formation temperatures of similar to 228 degrees to 249 degrees C. Mineralization is dominated by pyrite-marcasite-barite-anhydrite. Radiometric dating using the Ra-228/Ra-226 and Ra-226/Ba methods shows active chimneys to be {\textless}20 with most {\textless}2 years old. However, the chimneys at Clark show evidence for mixing with, and remobilizing of, barite as old as 19,000 years. This is consistent with Nd and Sr isotope compositions of Clark chimney and sulfate crust samples that indicate mixing of similar to 40{\%} seawater with a vent fluid derived from low K lavas. Similarly, REE data show the hydrothermal fluids have interacted with a plagioclase-rich source rock. A holistic approach to the study of the Clark hydrothermal system has revealed a two-stage process whereby a caldera-forming volcanic event preceded a later cone-building event. This ensured a protracted (at least 20 ka yrs) history of hydrothermal activity and associated mineral deposition. If we assume at least 200-m-high walls for the postulated (buried) caldera, then hydrothermal fluids would have exited the seafloor 20 ka years ago at least 550 m deeper than they do today, with fluid discharge temperatures potentially much hotter (similar to 350 degrees C). Subsequent to caldera infilling, relatively porous volcaniclastic and other units making up the cone acted as largescale filters, enabling ascending hydrothermal fluids to boil and mix with seawater subseafloor, effectively removing the metals (including remobilized Cu) in solution before they reached the seafloor. This has implications for estimates for the metal inventory of seafloor hydrothermal systems pertaining to arc hydrothermal systems.},
	keywords = {AUV ABE (Autonomous Benthic Explorer), AUV Sentry (Autonomous Underwater Vehicle)},
	issn = {0361-0128},
	author = {de Ronde, C E J and Walker, S L and Ditchburn, R G and Tontini, F Caratori and Hannington, M D and Merle, S G and Timm, C and Handler, M R and Wysoczanski, R J and Dekov, V M and Kamenov, G D and Baker, E T and Embley, R W and Lupton, J E and Stoffers, P}
}
@article {Deschamps2013,
	title = {{Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {14},
	number = {5},
	year = {2013},
	pages = {1609{\textendash}1625},
	abstract = {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{\textendash}14,000 years. The restored topography indicates that the axial morphology evolved from a smooth constructional dome {\textgreater}500 m in diameter, to a fault-bounded graben, {\~{}}500 m wide and 30{\textendash}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.},
	keywords = {AUV ABE (Autonomous Benthic Explorer)},
	issn = {1525-2027},
	doi = {10.1002/ggge.20110},
	url = {http://dx.doi.org/10.1002/ggge.20110},
	author = {Deschamps, A and Tivey, M A and Chadwick, W W and Embley, R W}
}
@article {Yoerger2007,
	title = {{Mid-ocean ridge exploration with an autonomous underwater vehicle}},
	journal = {Oceanography},
	volume = {20},
	number = {4},
	year = {2007},
	pages = {52{\textendash}61},
	keywords = {AUV ABE (Autonomous Benthic Explorer)},
	issn = {1042-8275},
	doi = {10.5670/oceanog.2007.05},
	author = {Yoerger, D R and Bradley, A M and Jakuba, M V and Tivey, M A and German, C R and Shank, T M and Embley, R W}
}
@article {Deschamps2007,
	title = {{Quantitative study of the deformation at Southern Explorer Ridge using high-resolution bathymetric data}},
	journal = {Earth and Planetary Science Letters},
	volume = {259},
	number = {1-2},
	year = {2007},
	pages = {1{\textendash}17},
	keywords = {AUV ABE (Autonomous Benthic Explorer)},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2007.04.007},
	url = {http://dx.doi.org/10.1016/j.epsl.2007.04.007},
	author = {Deschamps, A and Tivey, M A and Embley, R W and Chadwick, W W}
}
