Details:

Journal Title:
Journal of Volcanology and Geothermal Research
Personal Author:
Clague, David A. ; Zierenberg, Robert A. ; Paduan, Jennifer B. ; Caress, David W. ; Cousens, Brian L. ; ... More +
Clague, David A. ; Zierenberg, Robert A. ; Paduan, Jennifer B. ; Caress, David W. ; Cousens, Brian L. ; Dreyer, Brian M. ; Davis, Alice S. ; McClain, James ; Ross, Stephanie L. Less -
NOAA Program & Office:
NOAA General Documents
Description:
The Escanaba Segment, the southernmost of the Gorda mid-ocean ridge segments, contains thick sandy to silty turbidite deposits that are Pleistocene to Recent in age. Dozens of deep laccoliths and shallower sills intrude into these sediments. The intrusions uplifted hills of the unconsolidated turbidites and some fed surface lava flows supplied along steeply dipping reverse faults that surround some of the tallest uplifted hills. Multibeam bathymetric mapping at 1-m resolution and chirp subbottom profile (SBP) lines at ~150 m spacing show that the uplifted sediment hills have complex patterns of surface deformation and experienced debris avalanche landslides on over-steepened slopes formed by uplift along reverse faults. The uplifted hills are spatially associated with 262 hydrothermal chimneys that are several-m-tall and abundant at two main areas named NESCA and SESCA (for northern and southern Escanaba). Chimneys are more abundant and widespread than previously mapped. The uplifted hills are also spatially associated with over 600 previously unrecognized pockmarks that range from a few to over 100 m in diameter and are up to 24 m deep. The hydrothermal deposits and pockmarks are associated with oily sediment, oily sulfide deposits, and tar mounds on the seafloor. The intrusions provide the heat to mature hydrocarbons from organic carbon in the sediment and to drive hydrothermal circulation that deposits sulfides and sulfates on the seafloor, mostly surrounding the tallest hills overlying thick laccoliths. The frequency sweep (chirp) subbottom profiles show that most sills and all the laccoliths are deeper than the ~60 m penetration of the system. However, the thicknesses and depths of numerous shallow sills are mapped from the bathymetry and SBP data. The deepest intrusions are all domed or punched laccoliths, those of intermediate depth are thick inflated sills, and the shallowest are the thinnest sills, as determined from the height of the uplifted hills. For most intrusions, depth to the top of the intrusion is roughly 3 times the thickness of the intrusion. The dome laccolith under Central Hill, in the NESCA vent field, is the only laccolith with well-constrained thickness (from the height of the uplifted Central Hill) and depth (from ODP drill 1038H through the hill that bottomed in the upper part of the laccolith. Sediment thicknesses on top of lava flows that pre- and postdate emplacement of the laccolith that uplifted Central Hill, coupled with an average sediment accumulation rate of 17.8 cm/kyr over the past almost 8800 years indicated that active hydrothermal venting on Central Hill began before ~225 years ago (the inferred age of the NESCA Young lava flow) but after ~1685 years ago (the average inferred age of NESCA #1 lava flow).
Keywords:
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Geochemistry And Petrology Geophysics
Source:
Journal of Volcanology and Geothermal Research, 432, 107701
DOI:
https://doi.org/10.1016/j.jvolgeores.2022.107701
ISSN:
0377-0273
Format:
PDF
Publisher:
Elsevier BV
Document Type:
Journal Article
License:
https://creativecommons.org/licenses/by-nc-nd/4.0/
Rights Information:
CC BY-NC-ND
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:99c9682423d4838094cd889fbc1a9df2a2d42db3702738715f33f8c8adeb367d
Download URL:
https://repository.library.noaa.gov/view/noaa/59539/noaa_59539_DS1.pdf
File Type:

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