Current Conference:
Eclogites in Space and Time – Bridging the Micro to Planetary Scales

Rohnert Park, California, USA | 19–23 June 2025

Know Before
You Go Program and
Abstract Volume Field Guide
(Non-Peer Reviewed)

Welcome

Welcome to Rohnert Park, California, for the 2025 GSA Penrose Conference, which will also represent the 15th International Eclogite Conference (IEC-15). We are excited to bring together the international community of scientists working on eclogites and subduction-zone processes to discuss recent advances in diverse fields, catalyze breakthroughs in our understanding of subduction-zone processes, and chart future research on eclogites in space and time. Our location near the Franciscan subduction complex, which is among the first natural laboratories for the study of subduction processes, provides a fitting location for the conference and field trips.

We are thrilled to have over 98 participants from 16 countries attend the Penrose 2025/IEC-15. Fifty- six are Early Career scientists, including undergraduate and graduate students, postdoctoral fellows, research scientists, and junior faculty. Since 1982, the eclogite community has organized a series of international meetings and field trips focusing on high-pressure and ultrahigh-pressure processes under the auspices of the International Eclogite Conference, and we look forward to continuing this tradition of exchanging ideas and promoting collaboration.

We would also like to express our gratitude to our sponsors and supporting institutions for making this conference possible.

On behalf of the convenors and field trip leaders, we hope you enjoy the Penrose 2025/IEC-15.

International Eclogite Conference

Description

The multidisciplinary study of eclogites from micro to planetary scales over the past 50 years has significantly advanced our understanding of plate tectonics. Eclogites are both the recorders and drivers of planetary-scale tectonics, and their formation is involved in such diverse processes as the geochemical exchange between Earth’s surface and deep interior, intermediate-depth seismicity, and continental growth, collision, and evolution.

Objectives

The objective of this Penrose Conference is to bring together the international eclogite community and scientists working on subduction-zone processes to discuss recent advances in diverse fields (e.g., geodynamics, geochemistry, experimental petrology, and geochronology); catalyze breakthroughs in our understanding of subduction-zone processes; and chart future research on eclogites in space and time.

This Penrose Conference will represent the 15th International Eclogite Conference (IEC15) and will be the first time U.S.-based scientists host the international eclogite community at a dedicated conference.

Conference Format

The conference format will include oral presentations, poster presentations, breakout discussions, and mentoring opportunities for early career scientists. Attendees will be expected to observe the GSA Code of Ethics & Professional Conduct throughout the meeting.

The venue is close to some of the classic localities of the Franciscan Complex, which we will visit during two syn-conference field excursions. Learn more about the venue online.

Thematic Sessions

Eclogites, Micro to Macro Scales

What processes do eclogites and eclogite-facies rock reveal at different scales? How do new insights from micro-scale observations on high-pressure and ultrahigh-pressure (HP–UHP) metamorphic rocks better constrain and inform subduction-zone processes? This thematic session will explore the state of knowledge regarding bridging the scales in eclogite research.

Advances in Methods: Thermobarometry and Geo/ Thermochronology

Mineral assemblages preserved in HP–UHP metamorphic rocks challenge the assumption that equilibrium was attained during prograde, peak, and retrograde conditions. This thematic session will explore advances in thermo-barometry and geo/thermochronologic techniques used to determine the pressure-temperature-time-deformation (P-T-t-D) histories of eclogite and related rocks.

The Role of Eclogite in Geodynamics

This thematic session will explore how P-T-t paths and deformation histories of eclogites (and related rocks) can be used to improve our understanding of paleogeothermal gradients, and thus the thermal evolution of our planet. It will include how seismic tomography can be integrated with observations from exhumed rocks to constrain the role of eclogites in Earth’s geodynamic evolution.

The Franciscan and HP–UHP Rocks of the Circum-Pacific Realm

The Franciscan Complex of California is among the first natural laboratories for the study of subduction zones and subduction processes. This session will focus on how the Franciscan Complex and other HP–UHP terranes in the circum-Pacific realm formed and survived exhumation

to Earth’s surface. This thematic session will also explore how HP–UHP exhumation mechanisms differ between long-lived and transient subduction zones.

Rheology of the Subduction Interface: Deformation and Earthquake Processes

Can exhumed analogs in the subduction-related metamorphic rock record be used to constrain the rheology of the slab–mantle interface? How does the process of serpentinization affect fore-arc deformation and fluid transport in the mantle wedge? This thematic session will explore the rheology of the subduction interface as preserved in both the seismicity of active subduction zones and the geologic evolution of exhumed HP-UHP terranes.

Fluids, Melts, and Geochemical (Re)cycling in Subduction Zones

What are the roles of fluids and melts in the geochemical cycling in subduction zones? This thematic session will explore how observations on HP–UHP metamorphic rocks can constrain the sources, pressures, and volumes of fluids in subduction zones.

Summary of Key Dates

15 February 2025	Registration and payment deadline. Deadline for submission of final abstracts.
Mid-March 2025	Conference program finalized. Presenters will be provided information on their presentation mode (oral vs. poster) at this time.
18 June 2025	Arrival in Rohnert Park, California, USA; Airport shuttle available from San Francisco International Airport (SFO)
19-23 June 2025	Conference and Fieldtrips
24 June 2025	Participants depart from Rohnert, CA; Airport shuttle to SFO available from hotel

Lodging

Room costs are based on double occupancy rates. If you have a roommate preference, please indicate on your registration form. We will attempt to accommodate attendees who request their own room, subject to room availability and at an additional cost; please select this option at registration.

Meals

On conference days all meals will be provided at the hotel. On fieldtrip days, breakfast will be at the hotel, a boxed lunch will be provided, and participants will be free to choose where to have dinner (i.e., dinners on field trip days will be paid for by each participant; restaurant options will be provided). If you have any dietary restrictions (vegan, vegetarian, food allergies, etc.), please indicate these on your registration form so we can be sure your meal needs are accommodated.

Transportation

All attendees will be expected to make their own travel arrangements to arrive at the conference venue no later than the evening of 18 June 2025. All participants are expected to attend the full duration of the conference, and the registration fee covers dinner and accommodations for the night of 23 June. Airport shuttle transportation is available to/from San Francisco International airport (SFO), which will be the most convenient airport for most participants. The shuttle also serves Oakland International Airport. For details see: https://groometransportation.com/sonoma-county/

Map of SFO Airport Shuttles

Attendees may alternatively choose to provide their own transportation to Rohnert Park, CA (e.g., rental vehicle or personal vehicle for local attendees), but will be expected to use conference-provided bus transportation during the meeting (i.e., for field trips). Those who plan to provide their own transportation to the Doubletree by Hilton Hotel Sonoma-Wine Country must indicate during registration that they require parking at the venue.

In making travel plans, some participants may wish to consider spending an additional 1-2 days visiting additional high-pressure localities of the Bay Area on their own. AGU's Streetcar 2 Subduction guide describes stops accessible by public transit (note that we will be visiting Ring Mountain and Marin Headlands as part of our syn-conference field trips).

Presenter Information

Presentation format will be either oral or poster. Attendees will receive more details of their presentation format, including information on preparing an oral or poster presentation, upon abstract acceptance in mid-March.

International Attendees

Fill out and print out your personalized Letter of Invitation. If you require additional information on your invitation letter in order to obtain approval to travel or for your visa, please email us at penrose2025@geosociety.org.

Get your Letter of Invitation

Sponsors

Venue