Okeanos Explorer (EX1502L3): Oceano Profundo 2015: Exploring Puerto Rico's Seamounts, Trenches, and Troughs (ROV/Mapping)

Vessel: NOAA Ship Okeanos Explorer; Expedition Dates: April 9 - 30, 2015

Project Principals: Brian Kennedy, NOAA/OAR/OER (Expedition Coordinator); Derek Sowers, NOAA/OAR/OER (Mapping Lead)

From April 9-30, 2015, NOAA ship Okeanos Explorer, America's Ship for Ocean Exploration, surveyed unknown deep-sea ecosystems and potential geohazards off the coast of Puerto Rico and the US Virgin Islands. Over 37,500 km square of high-resolution multibeam sonar data was collected, revealing rugged canyons along shelf breaks, intricate incised channels, and large slumps and slope failures. Twelve remotely operated vehicle (ROV) dives, surveyed seamounts, escarpments, and submarine canyons at depths of 300-6,000 m. Additional ROV exploration of the water column occurred at depths of 800-1200 m. Dives included three of the deepest dives ever conducted in the Puerto Rico Trench and the first exploration of Exocet and Whiting seamounts. Discoveries included assemblages of deep-sea corals (>50 species), and observations of several rare and new species. For example, seastar Laetmaster spectabilis had not been documented since its original description in 1881 and a potential new species of benthopelagic ctenophore was observed at 3900 m in the Arecibo Amphitheater. Other expedition highlights included two rarely observed blind octopods (Cirrothauma murrayi); novel observation of a symbiotic association between predatory tunicates with polychaete associates; and approximately 75 species of demersal fishes, including a new species of wrasse and the first records of Shaefer's anglerfish and the ateleopodid jellynose in Puerto Rican waters. ROV dives traversed elements of the complete geological succession from ~1 km deep into the Cretaceous volcanic arc basement, across the carbonate platform sequence unconformity and into the uppermost Pliocene carbonates. Geological highlights included spectacular slope failure headwall scarps and sub-aerial karstic weathering of the youngest carbonates. In addition to the ROV dives, multibeam mapping operations were conducted at night. These efforts enabled mapping of new areas, filling in data holidays and re-mapping areas at higher resolution than what was previously available.

Arecibo Amphitheater (Guajataca Canyon)

Area

Arecibo Amphitheater (Guajataca Canyon); Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 10, 2015
Max Depth:	4062.8 Meters
Bottom Time:	6 Hours 50 Minutes 57 Seconds

Purpose

i) To investigate the lithology of the exposed rocks along the escarpment. ii) To identify features that could be related to failure of the escarpment/platform. And in particular to look for recent features that might be related to the January 2014 recent Magnitude 6 Earthquake. iii) To look for evidence of sediment flows emanating from the canyons. iv) To explore for fresh water seeps along the marginal escarpment. v) To document the biology living on and around the escarpment from 3000-4000m.

Septentrional Fault

Area

Septentrional Fault; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 11, 2015
Max Depth:	3675.8 Meters
Bottom Time:	4 Hours 3 Minutes 28 Seconds

Purpose

i) To investigate the lithology of the exposed rocks along the southern slope of the valley formed above the eastern termination of the Septentrional Fault. ii) To identify any deformation related to the Septentrional Fault, with a view to understanding why the fault apparently terminates at the eastern end of this valley. iii) To identify features that could be related to slope failure. iv) To look for evidence of sediment flows both within the valley and down the valley wall. v) To document the biology living on and around the slope from 2600-3650m.

Pichincho

Area

Pichincho; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 12, 2015
Max Depth:	n/a
Bottom Time:	n/a

Purpose

i) To explore possible habitats for deep water snappers and groupers. ii) To document the biology living on and around the un-named fault scarp from 600m to 300m depth. iii) To determine the lithology and stratigraphy of the rocks exposed by the fault. iv) To identify structural features that could be related to the fault.

Mona Canyon - West Wall

Area

Mona Canyon - West Wall; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 13, 2015
Max Depth:	3928.1 Meters
Bottom Time:	6 Hours 23 Minutes 18 Seconds

Purpose

i) To make geological and biological observations along a transect from 3900m to 3200m directly beneath the dive track of E/V Nautilus/Hercules dive H1300 which began at 2900m below sea level. ii) To look for and examine the late Cretaceous to Middle Eocene arc rocks which lie immediately below the Middle Oligocene to Late Miocene platform carbonate sequence. iii) To identify features that could be related to failure of the canyon wall. iv) To carry out five 10-minute horizontal mid water transects every 100m from 800-1200m to observe mid water biology. v) To document benthic communities along the canyon wall.

Mona Canyon - East Wall

Area

Mona Canyon - East Wall; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 14, 2015
Max Depth:	4025.7 Meters
Bottom Time:	3 Hours 16 Minutes 20 Seconds

Purpose

i) To carry out five 10 minute horizontal traverse mid water transects every 100m from 800-1200m to observe mid-water biology. ii) To document hard substrate megabenthos and other benthic communities along the canyon wall and to compare the communities to those found at similar depths on the west wall of Mona Canyon. iii) To observe lithology and structure along a transect from 4000m to 3300m to compare with observations of the west wall of Mona Canyon, including looking for evidence of faults on the east wall of the canyon. iv) To look for, and examine, the late Cretaceous to Middle Eocene arc rocks which lie immediately below the Middle Oligocene to Pliocene platform carbonate sequence. v) To identify features that could be related to failure of the canyon wall.

Platform

Area

Platform; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 15, 2015
Max Depth:	606.2 Meters
Bottom Time:	8 Hours 46 Minutes 48 Seconds

Purpose

i) To explore benthic habitats for deep water snappers and groupers. ii) To document the biology living on and around the un-named fault scarp from 600m to 300m depth. iii) To determine the lithology and stratigraphy of the rocks exposed by and in front of the fault. iv) To identify structural features that could be related to the fault.

Guayanilla Canyon

Area

Guayanilla Canyon; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 16, 2015
Max Depth:	2139.9 Meters
Bottom Time:	9 Hours 35 Minutes 44 Seconds

Purpose

i) To determine the lithology and stratigraphy of the rocks exposed in the east wall of the Guayanilla Canyon. ii) To traverse across the trace of the Investigator Fault in the canyon wall and to look for deformation related to the movement of that fault. iii) To document benthic communities living on and around the east wall of the canyon from 2150m to 1690m depth.

Engineering Dive

Area

Engineering Dive; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 25, 2015
Max Depth:	1678.1 Meters
Bottom Time:	3 Hours 40 Minutes 49 Seconds

Purpose

The purpose of the dive was to explore the biology and geomorphology of the wholly unexplored Gosnold Seamount.

Puerto Rico Trench - South Wall

Area

Puerto Rico Trench - South Wall; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 26, 2015
Max Depth:	5999.7 Meters
Bottom Time:	n/a

Purpose

i) Pressure test ROVs to 6,000 m. ii) Investigate the lithology and stratigraphy of the rocks exposed in the south wall of the Puerto Rico Trench. iii) To document benthic communities living on and around the southern wall of the trench at a depth of 6,000 m.

Pinnacles

Area

Pinnacles; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 27, 2015
Max Depth:	933.7 Meters
Bottom Time:	6 Hours 39 Minutes 23 Seconds

Purpose

i) To determine the lithology, structure and origin of two recently discovered ~100-200m diameter mounds/pinnacles sitting on the top of the gently sloping carbonate platform to the SE of St. Croix. ii) To document benthic communities living on and around these two mounds/pinnacles from 870m to 818m depth for the first mound/pinnacle and from 933m to 920m for the second smaller mound/pinnacle.

Exocet Seamount

Area

Exocet Seamount; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 28, 2015
Max Depth:	2900.7 Meters
Bottom Time:	5 Hours 35 Minutes 43 Seconds

Purpose

i) To carry out five 10 minute horizontal traverse mid water transects every 100m from 800-1200m to observe mid-water biology. ii) To document benthic communities living on and around the eastern margin of Exocet Seamount. iii) To determine the lithology and geological structure of the eastern margin of Exocet Seamount. iv) To compare the fauna found on Exocet with that found on seamounts to the north-east (Dog, Conrad & Noroit) and west (Grappler and Whiting).

Whiting Seamount

Area

Whiting Seamount; Northwest Atlantic Ocean; Caribbean Sea; Puerto Rico and U.S. Virgin Islands

Overview

Date:	April 29, 2015
Max Depth:	1303.3 Meters
Bottom Time:	8 Hours 40 Minutes 43 Seconds

Purpose

i) To document benthic communities living on and around the north-western margin of Whiting Seamount/Bank. ii) To determine the lithology and geological structure of the north-western margin of Whiting Seamount/Bank. iii) To compare the fauna found on Whiting Seamount with that found on seamounts to the north-east (Dog, Conrad, Noroit & Exocet).