Title: Submarine Volcanic Eruptions

Abstract: Submarine volcanic eruptions are poorly documented because they are largely hidden beneath the ocean surface and most of what they erupt is deposited on the sea floor. As a consequence they are not well understood, including the processes that drive eruptions and the fate of erupted materials. I will describe some of what we are learning from studies of the Havre eruption, the Hunga eruption (the highest eruption we ever recorded), and a recent IODP Expedition to the Hellenic volcanic arc.

Click here to watch the recorded lecture.

Title: Progress on a Deep Learning Enhanced Earthquake Catalog for Northern California.

Abstract: Developing enhanced earthquake catalogs is essential for nearly all aspects of seismology, including understanding foreshock and aftershock behavior, imaging the Earth structure, and identifying active faults. Here we present progress on a deep learning enhanced catalog for northern California from 2023, where we use the PhaseNet picker and the GENIE phase association algorithm to develop a catalog of ~4.2x more earthquakes than the routine NCEDC catalog. The set of seismic stations we use to develop this catalog is highly variable, with hundreds of stations throughout the bay area, and far fewer stations throughout the central valley and Sierras, as well as dense local networks at Parkfield and Geysers. Despite this heterogeneity, we find GENIE appears effective at associating picks reliably across the full spatial domain, spanning from south of Parkfield and Ridgecrest, to north of the Mendocino Triple Junction, and from the west coast into western Nevada. The model achieves this by using graph convolutions to combine information from nearby stations, which allows it to identify reliable signatures of events even for small earthquakes that only show up on a fraction of the network. Our results are further verified by confirming that ~95% of all reported NCEDC earthquakes are re-detected, and the spatial locations of new events improves the detected seismicity rate primarily at the expected fault locations. The Gutenberg-Richter distribution of the new catalog is consistent with the reference NCEDC catalog, but extends to a lower magnitude of completeness, and double difference relocation further refines the expression of faults and quarries throughout the region.

Click here to watch the recorded lecture.

Title: So You're Thinking About A Career in Economic Geology and Mineral Exploration...

Abstract:

A career in the search for ore deposits is one of the most rewarding ways to make a living.  Far more than just a job, you will surround yourself with people who share your passion for discovery.

In this day and age, a career in economic geology and mineral exploration might encompass a vast array of subjects and activities, including classical field geology, petrography, metallurgy, geotechnical, ore control, drilling, 3D modeling and resource estimation, environmental and permitting, social engineering, logistics, project and people management, marketing or running a company.  You might find yourself anywhere in the world, using planes, helicopters, trucks, 4-wheelers or mules to get there.  If travel is your thing, you might be the first person on the ground in a remote village, or living in a camp, in a tent, or a seaside resort.  You might be logging core, mapping an ore deposit, planning and laying out drill sites to test your model, compiling and analyzing data, giving presentations, going to conferences, building geological and resource models, working with engineers and metallurgists, supervising environmental studies, writing technical reports and a million other things.

A successful career in economic geology and mineral exploration takes flexibility, teamwork, an open mind, an ability to analyze large data sets, taking risks, learning from others and a willingness to embrace all aspects of the search for an economic deposit.

Here’s my story, and some helpful hints on how to jumpstart your career.

Title:  Drilling Volcanic Rifted Margins to Understand Large Igneous Provinces and Associated Global Warming.

Abstract: Continental breakup is a rare, but fundamental Earth event driven by massive internal forces. The splitting of Europe from Greenland some 56 million years ago was likely triggered by hot material rising from the deep mantle, forming a large igneous province. The breakup magmatism was associated with a global warming and extinction event, the Paleocene-Eocene Thermal Maximum (PETM). IODP Expedition 396 successfully drilled 20 holes on the mid-Norwegian continental margin to better understand continental breakup processes and to test the hypothesis that associated voluminous magmatism triggered the PETM. Hole locations were carefully selected on conventional and high-resolution 3D seismic data. In total, > 4 km of sediments and volcanic rocks were drilled, recovering 2 km of core. The expedition recovered the first sub-basalt rocks on the Norwegian margin, documenting the presence of granite and inter-basalt sandstones on the Kolga High. We also cored three different seaward dipping reflectors (SDR) facies units on the Vøring Margin, representing basaltic lava flows emplaced in sub-aerial, coastal, and deep marine environments, respectively. An Outer High named Eldhø, was sampled at the termination of the Inner SDR and recovered spectacular pillow basalt units. The PETM interval was cored at the ten Modgunn Arch and Mimir High holes. The Modgunn holes drilled into the upper part of a hydrothermal vent complex. High-resolution palynology and isotope geochemistry document that the hydrothermal venting took place near the start of the PETM, supporting the hypothesis that the global warming event was triggered by shallow-water eruption of greenhouse gases formed by heating of organic-rich sediments intruded by magmatic sills.
In conclusion, scientific drilling has provided essential data to document how the Earth’s internal processes have influenced the environment and life in deep time. To understand the environmental changes in the future, it is critical to keep on drilling the ocean basins to test new hypotheses and to discover our geological past.

Title:Tectonic Inversion and Buttressing: A Case for Cenozoic Contraction in Northern Oman

Abstract: 

The geology of northern Oman and eastern Arabia is distinctive because of the emplacement of the Semail Ophiolite onto the stable Arabia platform in the late Cretaceous followed by the later development of the Jebal Akhdar and Saih Haitat domes. East of Muscat, the Wadi Kabir Fault forms an important structure along which the northern edge of the Saih Hatat domes was unroofed.  In the Bandar Jissah area, Triassic carbonates occur in the footwall of the NNE-dipping Wadi Kabir Fault while rocks of the Semail Ophiolite, newly discovered rocks of the metamorphic sole, and a sequence of Paleogene-Eocene sedimentary rocks crop out in the footwall.  Some workers posit that the Wadi Kabir and associated faults form basin-bounding normal faults for the Bandar Jissah rift basin and that folds in the hanging wall cover sequence are the product of rollover during extension and basin formation.

However, our detailed mapping and kinematic analysis illustrates that folds in the hanging wall are contractional structures that formed due to tectonic inversion along the Wadi Kabir and other faults.  The overall shortening is modest (~10%) and primarily confined to the hanging wall rocks, consistent with buttressing against mechanically rigid rocks in the footwall of the Wadi Kabir Fault.  These structures require an interval of N-S directed shortening in northern Oman that post-dates the deposition of mid-Eocene marine sediments in the Seeb Formation. The Wadi Kabir Fault also has localized zones of listwaenite preserved in its damage zone that is derived from ophiolitic rocks in the hanging wall. K-Ar age dating of gouge along the Wadi Kabir Fault yields ages of ~90 Ma and 58 ± 2 Ma, consistent with a long history of slip.  Collectively, the Wadi Kabir Fault is a long-lived structure that’s experienced multiple episodes of extensional and contractional slip since the Cretaceous.

Title:How Fast, How Deep, and How Much? — Understanding Groundwater Hydrology with Passive Seismic Interferometry

Abstract: With climate change and population growth, humanity faces two critical global challenges: water security and the transition to clean energy. Tackling these issues requires affordable, high-resolution monitoring of fluid systems, such as groundwater and geothermal reservoirs, hidden in the Earth's shallow subsurface. In this seminar, I will introduce a novel, cost-effective method for aquifer monitoring using passive seismic interferometry. The promise of this approach will be demonstrated through case studies of aquifers across Greater Los Angeles. I will validate the effectiveness and unique advantages of seismic sensing by comparing it with borehole data, remote sensing, and hydrological simulations. I will then explore how this seismic method offers new insights into depth-dependent changes in aquifer storage over an event to decadal timescales with high spatial resolution. These pilot applications highlight the potential of leveraging seismic instruments worldwide to quantitatively assess the response of shallow fluid systems to weather extremes and anthropogenic activities.

Title: Drilling Down the Data: A Deep Learning Dive into IODP Cores

Abstract:

The Integrated Ocean Drilling Program (IODP) stands as a testament to human curiosity, having amassed a diverse collection of drilling cores which provide a window into geological processes. Core data is pivotal for understanding our planet’s past, present, and future. Despite this richness, extracting meaningful insights from core description poses significant challenges due to the inherent complexity and variability of the data, the amount of existing material, and the subjectivity of the interpreter.

Focusing largely (but not exclusively) on carbonate rocks, characterized by their heterogeneity at all observational scales, I will discuss how my research group and I have pioneered the application of deep-learning computer vision to geological core interpretation. This technology transcends the traditional, tedious manual interpretations of cores, offering a rapid, and often more accurate, alternative for delineating depositional environments and sequence stratigraphy. Convolutional neural networks (CNNs) form the backbone of our approach, enabling us to process core data with unprecedented efficiency. I will show that these sophisticated models, when correctly trained and fed with substantial datasets, serve as invaluable tools for geologists, outpacing conventional methods in speed without compromising on precision.

Our early work was centred on transfer learning, an AI approach that adapts pre-existing models to new data. I will show that this remains one of the best way to train classification algorithms for geological dataset. But we also worked on generative algorithms that fill gaps in our sampling of core imagery: for instance, we use Generative Adversarial Networks (GANs) to transform the resistivity images from formation micro scanners into representations mirroring actual core photographs, thus enhancing the interpretability for geologists irrespective of their background in downhole tools.

We tackle the often-limiting factor of dataset size in two ways. First, we recourse to generative AI to oversample our training set. Second, we also explore semi-supervised learning techniques.  I will demonstrate that we successfully train models on core deformation images from IODP with minimal labelled data, achieving accuracy on par with, if not exceeding, that of transfer learning models.

The arc of my talk will thus chart the course of deep learning's evolution from a mere auxiliary tool to a pivotal force in geological sciences. Results from my research group and the broader research community indicate a promising future where deep learning not only streamlines the interpretation process but also provides robust, systematic insights that could revolutionize our understanding of geological data.

Title: The interplay between fluids and deformation: Comparisons Between the Subduction Interface and Oceanic Detachment Faults

Abstract: 

Fluids, metamorphism and metasomatism including serpentinization and magmatism can weaken the lithosphere and lead to mechanical and chemical properties that affect the strength and slip behavior of fault zones. However, the competing mechanisms that control strain localization and exhumation rates and nature of fluids during these processes are still poorly understood.

In the first part of the talk, I will show the importance of in-situ apatite petrochronology from three subduction complexes from the Hellenic subduction zone. Apatite can record subduction processes including metamorphism, metasomatism, and underplating due to its ability to deform, recrystallize, and record chemical and mechanical processes across the Pressure/Temperatures conditions that span the depths at the bottom of the subduction seismogenic zone. These tools allow us to map out the entire journey of subducted and exhumed rocks and help us better understand deformation and fluids likely associated to slow slip and tremor along the plate interface.

In the second part of the talk, I will show new data from recovered cores from IODP Expedition 402 that revealed in-situ sections of serpentinized mantle exhumed during extension in the Tyrrhenian backarc basin. Two drill sites comprise a sequence of variably deformed granitic gneisses intercalated with ~cm-thick slivers of peridotites and basalts, and a heterogeneous section of primarily serpentinized peridotites with granitoids emplaced between the ultramafics. Geochronologic and micro-structural constraints as well as stable isotope data suggest that the granitoids accommodated the majority of deformation during exhumation along the detachment fault. Additionally, oxygen isotopic analyses suggest higher temperatures of serpentinization and are observed along the fault zones potentially due to seismic slip.

Title: Do microbes care about landslides?  Using geomorphic models to inform stocks and cycling of soil organic carbon

Abstract:

Soils play a central role in the global carbon cycle and constitute a key component of natural climate solutions that require quantitative predictions of soil organic carbon (SOC) dynamics at local to regional scales. In hilly and mountainous terrain, variations in uplift and stream incision generate landslides and gradients in erosion and hillslope morphology that control soil properties and thus impact the abundance and persistence of SOC. Here we use geomorphic theory, field observations, topographic analyses, and soil biogeochemical analyses to identify how landscape evolution regulates the abundance and residence time of soil organic carbon in erosional settings. Our analyses reveal significant variations in SOC stocks and cycling that are important for informing carbon markets and restoration strategies, but are not captured by existing inventories and databases.