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Exploring Deep-Sea Methane Seeps Along the Chile Margin

Past Expedition

Primary Goal

Search for, explore, and characterize methane seeps along the coast of Chile

Dates

October 11 - December 5, 2024

Location

Pacific Ocean

Vessel

Research Vessel Falkor (too)

Primary Technology

Sub-bottom profiler, remotely operated vehicle, methane sensor, sediment coring devices, multibeam sonar

Overview

From October 11 to December 5, 2024, an interdisciplinary and international team of researchers explored the unique geological and biological systems of the Chile margin during an ambitious expedition on Schmidt Ocean Institute’s Research Vessel Falkor (too) . With support from NOAA Ocean Exploration, one of the expedition projects focused on collecting data to unravel the complexities of methane seep systems — a type of cold seep and a significant contributor to oceanic carbon cycling — in this tectonically active region.

Project Details

This project focused on mapping and characterization of methane seep ecosystems and their interactions with tectonic, climatic, and oceanographic processes along four key sites: Limarí Seeps, El Quisco Seep Area, Concepción Methane Seep Area, and Mocha Island Seep Area. Using advanced tools and techniques, the researchers surveyed the seafloor and subsurface structures.

A high-resolution sub-bottom profiler was used to investigate the shallow subsurface structure of methane seepage. This state-of-the-art technology provided critical insights into the subsurface structure and geology while also informing the precise positioning of the sediment coring devices.
Remotely operated vehicle (ROV) SuBastian was used for precise sampling and high-definition imaging of seep habitats. The ROV enabled the researchers to observe active methane emissions and collect samples from microbial mats and methane-derived authigenic carbonates.
Geochemical sensors and samplers were used to collect data on methane fluxes, fluid migration pathways, and the geochemical characteristics of the seep environments. Among the sensors was an in situ methane sensor, now known as SAGE (Sensing Aqueous Gases in the Environment) used for precise and real-time measurements of methane concentrations in the water column developed with support from NOAA Ocean Exploration.
Sediment coring devices were used to collect sedimentary records to reconstruct methane seepage history. This was the first time a large-diameter gravity corer that can collect samples up to 6 meters (20 feet) in length was deployed off Falkor (too).
Shipboard and ROV-mounted multibeam sonar systems were used to map the seafloor and individual seeps.

The multicorer being lowered into the ocean from Research Vessel Falkor (too) to collect data for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. The device can retrieve multiple sediment and water samples from the seafloor during a single deployment. — The multicorer being lowered into the ocean from Research Vessel *Falkor (too)* to collect data for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. The device can retrieve multiple sediment and water samples from the seafloor during a single deployment. *Image courtesy of Mónika Naranjo-Shepherd/Schmidt Ocean Institute.*
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The gravity corer strapped down to the back deck of Research Vessel Falkor (too). This tool was used to collect sediment cores from the seafloor for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. — The gravity corer strapped down to the back deck of Research Vessel *Falkor (too)*. This tool was used to collect sediment cores from the seafloor for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. *Image courtesy of Adam Skarke.*
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Regional map of central Chile. Black dots indicate locations of methane seep exploration sites. Blue dots indicate ports. The expedition departed from Valparaiso, Chile, and returned to port at the end of the first leg in Puerto Montt, Chile.
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Accomplishments

While at sea, this project team:

Successfully and safely completed 22 total deployments of sediment coring devices (the gravity corer and a multicorer), providing valuable sedimentary records for methane seepage analysis.
Mapped over 10,000 square kilometers (3,861 square miles) of seafloor, yielding insights into the region’s underwater landscape.
Conducted 23 ROV dives at methane seep and submarine canyon sites, significantly expanding the dataset of these dynamic environments.
Mapped each of the four sites in high resolution (1×1 meter grid size) using the multibeam system on ROV SuBastian, providing precise visualization of seep features and habitats.

First look at a large-diameter sediment core taken at a methane seep site off the Chile margin. The surface of the core has the remains of tube worms, indicative of a seep community. The core provided insights to the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. *Image courtesy of Jeff Beeson.*
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Remotely operated vehicle (ROV) pilots aboard Research Vessel Falkor (too) use ROV SuBastian’s manipulator arm to take a core sample of bacteria and sediment near the El Quisco Seep Area. — Remotely operated vehicle (ROV) pilots aboard Research Vessel *Falkor (too)* use ROV *SuBastian*’s manipulator arm to take a core sample of bacteria and sediment near the El Quisco Seep Area. *Image courtesy of ROV SuBastian/Schmidt Ocean Institute.*
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Methane bubbles rising from the seafloor captured in a gas sampler. The research team used remotely operated vehicle SuBastian to collect samples while exploring the Concepción Methane Seep Area for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. — Methane bubbles rising from the seafloor captured in a gas sampler. The research team used remotely operated vehicle *SuBastian* to collect samples while exploring the Concepción Methane Seep Area for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. *Image courtesy of ROV SuBastian/Schmidt Ocean Institute.*
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3D perspective view of multibeam bathymetry collected at the Concepción Methane Seep Area for the Exploring Deep-Sea Methane Seeps Along the Chile Margin project. Methane seep plumes are shown in white and coring locations are shown as black bullseyes. *Image courtesy of Adam Skarke.*
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Next Steps

Back on land and in the lab, the researchers are analyzing collected data and samples in detail. They are integrating geophysical data with sediment and geochemical findings to model fluid migration pathways and reconstruct the history of methane seepage. They will share their results through peer-reviewed publications, conference presentations, and public data repositories.

Future work includes expanding methane seep investigations to other underexplored regions and developing predictive models for methane dynamics under changing conditions.