The Central Coast Branch is pleased to present:
Insights from a Low-Porosity Hydrothermal Aquifer Tracer Study
Presentation:
An added Sulphur Hexaflouride (SF6) push-pull tracer experiment in sub-seafloor hydrothermal fluid circulating in the eastern flank of the Juan de Fuca plate was conducted from 2010-2014. Experiment planning and initial data analyses assumed a point-source instantaneous tracer injection, analogous to a high porosity terrestrial groundwater system. Additional tracer breakthrough data from adjacent boreholes has given reason to reevaluate this conceptual model, potentially replacing the original terrestrial analog model with one taking into account extremely limited effective porosity and 10-100x lateral anisotropy, controlled by ridge-parallel faulting orienting the connectedness of fractures and pore in the basalt basement aquifer. A near-instantaneous breakthrough downgradient of the injection site suggests that effective porosity is so limited that the injectate volume alone was sufficient to displace fluid 200-300 meters. A secondary tracer was injected in two pulses hours apart and intended to thoroughly mix in the vicinity of the borehole, effectively producing one signal. Instead, it produced two distinct breakthroughs, supporting the ultra-low porosity hypothesis. Continuous autonomous sampling systems have provided high-resolution data in this fractured rock aquifer and provided opportunities to refine tracer study planning in low porosity systems and analytical techniques for dissolved gas tracers. The methods, results, and interpretations of these data have the potential to guide future sub-seafloor aquifer studies and may be useful in terrestrial fractured-rock aquifer settings for potable use studies, contaminant transport, and geothermal reservoir applications.
Speaker Bio:
Menso de Jong, Ph.D., Candidate Hydrogeology UCSB Earth Science
Menso de Jong studied Earth Science at Cal Poly SLO (2011) and became interested in hydrogeology while working at Padre Associates in San Luis Obispo. He returned to academia, earning an MS Hydrogeology under Dr Jean Moran, Cal State East Bay (2014);and PhD Hydrogeology under Dr Jordan Clark, UC Santa Barbara (2018, hopefully). His projects have focused on groundwater tracers and water quality. In his free time, he enjoys mountain biking and exploring National Parks.
Meeting Costs:
Member: $35.00
Non- Member: $45.00
Student: $10.00
*On-site payment is cash or check only and registrants are encouraged to pay by credit card on the website
If you register after Noon on Tuesday, February 19th through the start of the meeting, registration will be $50.00 for members and non-members. (Excluding Students)
Agenda:
6:00-6:15 p.m. – Registration & Networking
6:15-7:00 p.m. – Dinner, Announcements & Business Meeting
7:00-8:00 p.m. – Keynote Speaker
*Students that attend only the Keynote Speaker portion do not have to pay
Questions about the meeting, please telephone Jeff Kubran at 805-963-0651 or email him at jkubran@dudek.com.