SA

SA/NT Tech Night - A Holistic Subduction/ Metasomatized Lithosphere Model for Orogenic Gold Deposits

Thursday, June 20, 2019
17:30
19:30

The ASEG SA/NT branch will meet on Thursday 20th June at 5:30 pm for a 6:15 pm start. 

We have Emeritus Professor David Groves speaking on, 'A Holistic Subduction/ Metasomatized Lithosphere Model for Orogenic Gold Deposits. '

David was recognised as a National Geoscience Champion by the Australian Geoscience Council in 2018, and we are honoured to have him present to us. 

https://www.agc.org.au/geoscience-in-australia/national-geoscience-champ...

Details:

Date and time: Thursday 20th June, 5:30 pm for 6:15 pm start

Cost: Free for ASEG members and students, $10 for non-members

Venue: Balcony Room, Hotel Richmond, 128 Rundle Mall, Adelaide, 5000

RSVP: Via Eventbrite (RSVP only, payment for non members to be paid in cash at the door)

https://www.eventbrite.com.au/e/national-geoscience-champion-emeritus-pr...

Hope to see you there!

 

Abstract

A holistic model for the origin of orogenic gold deposits and its implications for exploration

The term orogenic gold deposit has been widely accepted for the majority of gold-only lode-gold deposits, but there has been continuing debate on their genesis. Early syn-sedimentary or syn-volcanic models and hydrothermal meteoric-fluid models are now invalid. Magmatic-hydrothermal models, except for rare examples of intrusion-related gold deposits, fail because of the lack of consistent spatially –associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely-accepted models involve metamorphic fluids, but the source of these fluids continues to be hotly debated. Intra-basin sources within deeper segments of the hosting supracrustal successions, the underlying continental crust, subducted oceanic lithosphere with its overlying sediment wedge, and metasomatized lithosphere are all potential sources. Several features of Precambrian orogenic gold deposits are inconsistent with derivation from a continental metamorphic fluid source. These include the presence of hypozonal deposits in amphibolite-facies domains, the proposed source region of the metamorphic fluids, their anomalous multiple sulfur isotopic compositions, and problems of derivation of gold-related elements from devolatilization of dominant basalts in the sequences. The Phanerozoic deposits are largely described as hosted in greenschist facies domains, consistent with supracrustal devolatilization models. A notable exception are the deposits of the giant Jiaodong gold province of China, where ca 120 Ma gold deposits are hosted in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. Other deposits in China are comparable to those in the Massif Central of France, in that they are hosted in amphibolite-facies domains or clearly post-date regional metamorphic events imposed on hosting supracrustal sequences. If all orogenic gold deposits have a common genesis, the only realistic source of fluid and gold is from devolatilizion of a subducted oceanic slab with its overlying gold-bearing sulfide-rich sedimentary package, or the associated metasomatized mantle wedge, with CO2 released during decarbonation and S and ore-related elements released from transformation of pyrite to pyrrhotite at about 500°C. Although this model satisfies all geological, geochronological, isotopic and geochemical constraints, and is consistent with limited computer-based modelling of fluid release from subduction zones the precise mechanisms of fluid flux, like many other subduction-related processes, are model-driven and remain uncertain.

In terms of exploration significance, the model confirms the ubiquitous distribution in paleo-subduction environments of all geological ages. It stresses the importance of lithosphere-tapping fault and shear zone systems that can tap fluids from the Moho and below. It also de-emphasizes reliance on exploration in greenschist-facies terranes, opening up opportunities in less-explored amphibolite-facies terranes. In fact, some of the more recent orogenic gold discoveries were made in amphibolite terranes in Western Australia (e.g. Tropicana) and Quebec, Canada (e.g. Eleonore).  

 

Bio

David Groves was born in Brighton, England, and migrated to Tasmania where he was educated at Hobart High School and at the University of Tasmania, completing a PhD under the mentorship of Mike Solomon. After a period with the Geological Survey of Tasmania, David was appointed Lecturer in Economic Geology at the University of Western Australia (UWA) in 1972. In 1987, he was awarded a Personal Chair at UWA and formed the Centre for Strategic Mineral Deposits, which morphed into the Centre for Global Metallogeny, with him as Director, and which became the Centre for Exploration Targeting after his retirement as Emeritus Professor. He had a very successful academic career in terms of highly-cited published papers and book chapters, keynote and invited lectures, and mentorship of many outstanding postgraduates, being awarded 12 medals and prizes, including the SEG Silver and Penrose Gold Medals and the SGA-Newmont Gold Medal, and being inducted into the Australian Academy of Sciences as a Fellow. Since his retirement from UWA, David has continued to write papers and mentor staff and students at the China University of Geosciences in Beijing (CUGB), as well as consult to industry, being involved in discovery of two > 1Moz gold deposits during greenfield exploration in Tanzania and Ethiopia.

In 2018, he was made a National Geoscience Champion by the Australian Geoscience Council and recognized as one of the 125 Faces of Geoscience by the Australasian Institute of Mining and Metallurgy. In recent years, David has also published three novels, with “The Plagues’ Protocol” having a “geological detective” as the main left-field thinking character. He has also commenced writing novels for a Chinese audience, the first in press being “Destiny on Magic White Mountain”, again with a strong mineral exploration background. He hopes to help popularize geology through his novels as part of his role as National Geoscience Champion.

 

SEG DISC 2019: Physics and Mechanics of Rocks: A Practical Approach

Tuesday, August 27, 2019
09:00
17:00

 See here for more details adn registration: https://seg.org/Education/Courses/DISC/2019-DISC-Manika-Prasad

Intended Audience

  • Seismic imagers and interpreters who want to learn how fluids, stress, and other environmental effects change seismic signatures
  • Geophysicists who wish to derive rock properties and constrain well-to-seismic ties
  • Geologists and sedimentologists looking to develop predictive models of sedimentary environments and stratigraphic events
  • Reservoir engineers to build porosity, permeability, and fluid coverage models for reservoir simulations using 3D and 4D seismic data
  • Basin modelers and completions engineers to evaluate stresses from well log and seismic data
  • Geoscientists doing formation evaluation and well logging interpretations
  • Basin managers and team leaders who wish to evaluate the accuracy of predictions and understand risk and errors in models

Prerequisites (Knowledge/Experience/Education Required)

Attendees should have an understanding of basic rock properties such as porosity, permeability, sediment compositions and depositions, and structural geology. It will be helpful to have familiarity, but not necessarily expertise, in seismic properties. The accompanying textbook will include mathematical details, data and problem solutions for mineral modulus calculations, rock stiffness calculations for textural symmetries, velocity binning in flow zones, pore stiffness, and Gassmann fluid substitution. The lecture will focus on fundamental rock physics principles, applications, and analysis of results.

Course Outline

The course is organized into two main sections: Section I. Rock Physics Fundamentals (introductory section) and II. Advanced Topics in Rock Physics (application section):

Rock physics fundamentals

In this section, I will:

  • Review fundamental principles underlying rock physics, and rock properties
  • Investigate the effects of fluids on rock properties
  • Derive basic rock physics correlations and explain why and how they work
  • Review rock properties that can be mapped with remote sensing

Advanced Topics in Rock Physics

In this section, the student is introduced to:

  • Poroelasticity
  • Attenuation and dispersion
  • Geomechanics
  • Complex electrical conductivity and permeability
  • Investigate the causes for complications and deviations from basic correlations
  • Examine existing empirical and theoretical models
  • Discuss selected case studies in rock physics

Learner Outcomes

On completion of the course, the learner should be able to

  • Describe and explain the applications of rock physics for reservoir characterization, formation evaluation, and field monitoring
  • Identify and evaluate existing and potential technologies applicable to rocks physics and rock mechanics for reservoir/formation studies
  • Identify, list, and describe the physical properties of rock, and relate these properties to the mechanical behavior of rocks
  • interpret and predict the effect of mineral properties (e.g. clay minerals) on the load-bearing capacity and strength of rocks
  • Integrate and model elastic wave propagation, electrical conductivity, and fluid flow in rocks
  • Evaluate and assess errors in experimental data, uncertainty, and the value of theoretical models
  • Develop expertise in rock physics interpretations of seismic and electrical conductivity to identify fluids and quantify saturations
  • Gather key strengths in rock physics interpretations by developing a broad understanding of existing or potential technology transfers between engineering and earth science fields that relate rock physics to reservoir geophysics and reservoir engineering
  • Gain knowledge and expertise to understand physical and mechanical behavior of rocks through examples of stress-dependent changes in strains, seismic velocity, electrical conductivity, and pore structure
  • Interpret rock physics and rock mechanics data and model elastic wave propagation, electrical conductivity, and fluid flow in rocks
  • Assess errors in experimental data, assess the uncertainty and the value of rock physics models
  • These learning objectives will allow geoscientists and engineers to:
  • Distinguish major trends in and control factors for velocity and impedance changes in the subsurface
  • Describe and evaluate velocity and impedance data for changes in fluids and stresses
  • Apply basic rock physics techniques to evaluate reservoirs
  • Identify and select the best practice workflows when using rock physics for seismic interpretations
  • Analyze complex conductivity data to interpret reservoir properties

 

Abstract

Rock physics is an interdisciplinary branch of geophysics that explains geophysical remote sensing data, such as seismic wave velocities and electrical conductivity, in the context of mineralogy, fluid content, and environmental conditions. Thus, rock physics interpretations often require inputs from physics, geology, chemistry, chemical engineering, and other fields. For example, seismic waves travel faster in cemented rocks than in loose sediments. Since the physical behavior of rocks controls their seismic response, rock physics brings key knowledge that helps with the interpretation of rock properties such as porosity, permeability, texture, and pressure. Rock physics combines indirect geophysical data (such as seismic impedance, sonic log velocities, and laboratory measurements) with petrophysical information about porosity, fluid type, and saturation for use in reservoir characterization, evaluation, and monitoring. Typically, rock physics is used by petroleum engineers doing reservoir simulations, geologists evaluating over-pressures and making basin models, and anyone doing a monitoring survey to map fluids from 4D seismic. For all such purposes, an understanding of wave propagation is required to relate seismic properties (e.g. velocity and attenuation) to the physical properties of rocks and to evaluate seismic data in terms of subsurface petrophysical parameters.  For example, an application of rock physics is seen in 4D seismic data (i.e. repeated seismic data acquired from the same field), where fluid saturation changes are evaluated from changes in velocity using fluid substitution models. Another rock physics application is to understand and predict the effect of clay minerals on the load-bearing capacity and strength of rocks using fundamental knowledge about the properties of clay minerals (e.g. CEC, surface area, dispersability, charge, sorption, plasticity, etc.), the clay water content, as well as the effects of their distribution within the rock. Thus, an effective prediction of rock properties from indirect measurements requires a solid understanding of the physical behavior of rocks under in situ conditions of pore and confining pressures and fluid saturations.

During this one-day short course, I will provide the earth scientist and engineer with a foundation in rock physics to describe the physical processes that govern the response of rocks to the external stresses essential for reservoir characterization. The course will also offer practical guidance to help better analyze existing data. A major goal of this course is to offer practical instruction and provide working knowledge in the areas of rock physics and rock mechanics for rock characterization.

SA Technical Night - Application of Gravitational Curvature Analysis to Structural Domaining of Geology

Wednesday, May 8, 2019
17:30
19:00

Details 

Time/Date: 5:30 pm for drinks and nibbles for 6:15 pm start on Wednesday 8th May

Title: Application of Gravitational Curvature Analysis to Structural Domaining of Geology

Speaker: Matthew Zengerer, Principal, Gondwana Geoscience

Cost: Free for members and students, $10 for non-members, includes drinks and nibbles

Venue: Coopers Alehouse, 316 Pulteney St, Adelaide, SA 5000

 

Biography

Matthew Zengerer is the founder of Gondwana Geoscience, a petroleum and mineral services consultancy operating since 2016. Matthew has an undergraduate Geoscience degree from Flinders University and a postgraduate Geophysics degree from the University of Tasmania. He has worked as both a geologist and a geophysicist, primarily the latter, beginning his career in geophysical and geological field data acquisition in 1998, before shifting into geophysical data processing in 2001. He subsequently moved into exploration, performing processing, modelling and interpretation services. He has worked for government, mineral, geothermal and petroleum commercial entities and trained and promoted geophysical and geological software to industry across the globe, and lived in Australia, the UK and France. Matthew is now considered a specialist in gravity gradiometry and potential fields, though he has worked at times in several geophysical disciplines. When he finds the time, he enjoys writing papers and presenting at international conferences.

 

SEG Distinguished Lecturer Tour: Boris Gurevich

Wednesday, March 13, 2019
17:30
19:00

2019 Pacific South Honorary Lecturer Tour

Seismic attenuation, dispersion, and anisotropy in porous rocks: Mechanisms and Models
Boris Gurevich, Curtin University and CSIRO, Perth, Australia

Understanding and modeling of attenuation of elastic waves in fluid-saturated rocks is important for a range of geophysical technologies that utilize seismic, acoustic, or ultrasonic amplitudes. A major cause of elastic wave attenuation is viscous dissipation due to the flow of the pore fluid induced by the passing wave. Wave-induced fluid flow occurs as a passing wave creates local pressure gradients within the fluid phase and the resulting fluid flow is accompanied with internal friction until the pore pressure is equilibrated. The fluid flow can take place on various length scales: for example, from compliant fractures into the equant pores (so-called squirt flow), or between mesoscopic heterogeneities like fluid patches in partially saturated rocks. A common feature of these mechanisms is heterogeneity of the pore space, such as fractures, compliant grain contacts, or fluid patches. Using theoretical calculations and experimental data, we will explore how this heterogeneity affects attenuation, dispersion, and anisotropy of porous rocks. I will outline a consistent theoretical approach that quantifies these phenomena and discuss rigorous bounds for attenuation and dispersion.

Time table

Date State Venue Start time Contact
13 March WA Celtic Club, 2nd floor, 48 Ord Street, West Perth 18:00 Heather Tompkins
15 March ACT Geoscience Australia 12:30 James Goodwin
19 March Qld XXXX brewery (Alehouse), Black Street, Milton 17:30 Ron Palmer
20 March NSW 95-99 York St 18:00 Mark Lackie
21 March Vic The Kelvin Club 18:00 Seda Rouxel
25 March SA/NT Coopers Alehouse 18:00 Kate Robertson
27 March Tas Geology Lecture Theatre, University of Tasmania 13:00 Mark Duffett

Biography

Boris Gurevich has an MSc in geophysics from Moscow State University (1976) and a PhD from Institute of Geosystems, Moscow, Russia (1988), where he began his research career (1981–1994). In 1995–2000 he was a research scientist at the Geophysical Institute of Israel, where he focused mainly on diffraction imaging problems. Since 2001, he has been a professor of geophysics at Curtin University and advisor to CSIRO (Perth, Western Australia). At Curtin he has served as Head of Department of Exploration Geophysics (2010–2015) and since 2004 as director of the Curtin Reservoir Geophysics Consortium. He has served on editorial boards of Geophysics, Journal of Seismic Exploration, and Wave Motion. He is a Fellow of the Institute of Physics and has more than 100 journal publications in the areas of rock physics, poroelasticity, seismic theory, modeling, imaging, and monitoring of CO2 geosequestration. His research achievements include development of advanced theoretical models of seismic attenuation and dispersion in heterogeneous porous rocks.

Sponsors

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SA/NT St

Friday, March 15, 2019
17:00
19:00

The Annual Student Pizza Night will be held on Friday March 15th, jointly with the Adelaide University Geological Society. Each year we hold this event at the University of Adelaide with the aim to promote the opportunities and benefits of studying geophysics to undergraduate students. We will have industry professionals giving talks on their careers along with pizza and drinks with a chance for industry professionals and students to network. We hope as many members as possible can make it to chat with the students and share their own experiences.

This year we will be joined by Dr Stephan Thiel from the Geological Survey of South Australia, and Bonnie Lodwick, from Santos. This represents a fantastic chance for students to hear about the breadth of opportunities that our industry can offer them and a great opportunity to network with industry and government geophysicists. The ASEG SA/NT Branch is very thankful for Stephan and Bonnie for agreeing to join us.

Please note that due to the Fringe the Mawson Building will be locked. Some members of ASEG will remain around the main entrance to let participants in. After the pizza and talks there will be ample opportunity for networking. Then there is the opportunity to continue networking a little more informally, and watch some live music at the RCC Fringe area (free entry before 9 pm) just outside the Mawson Building. After dark, 'Dusk till Dawn' transforms the grounds of RCC Fringe into a playground of music, art and light, with over 120 artists and musicians performing over five weekends. For more information, see here: https://adelaidefringe.com.au/fringetix/rcc-fringe-dusk-till-dawn-af2019

 

Title: Annual Student Pizza Night

When: Friday 15th March 2019

Time: Food, Drinks and Presentations from 6 pm; please be aware doors to the Mawson close at 5pm due to the Fringe, access via main (southern) entrance only.

Where: Sprigg Room, Upstairs in the western end of the Mawson Laboratories, University of Adelaide, corner of Frome Rd and Victoria Dr.

Cost: Members and students: Free, Non-members $10

SA/NT Technical night: Compressive Seismic Imaging

Wednesday, February 27, 2019
17:30
19:00

Compressive Seismic Imaging (CSI): Keith Millis, SAExploration

The Shannon-Nyquist Sampling Theorem has long governed seismic theory and formed the basis for proper seismic design. It states that a continuous function can be completely described by a series of discrete samples, provided the sample rate is at least two times the maximum frequency present within the signal. Compressive Sensing (CS) – a technique used in medical imaging and digital cameras – has shown that perfect reconstruction is still possible when the sample-rate criteria is not satisfied.

Compressive Seismic Imaging (CSI) is the application of CS theory to seismic. Through proper spatial sampling, known as Non-Uniform Optimal Sampling (NUOS), CSI has shown distinct advantages to seismic imaging, including drastic increases in fold, trace density and bandwidth; proper noise attenuation of previously challenging surface wave modes; improved imaging both generally and in areas with substantial infrastructure; footprint attenuation; among others. As the evolution of seismic imaging continues, we will highlight the impact of CSI, blended acquisition, and broad bandwidth, with examples from various case studies.

Cost

$10 for non members, free for students and members.

Cocktail food and drinks provided.

Biography

Currently Lead Geophysicist at SAExploration, Keith has as distinct passion for our profession and energy industry as a whole. An active member of the SEG, CSEG, and APEGA, Keith is currently a member of the CSEG Chief Geophysicists Forum. He has recently been on the CSEG Executive as Director of Communications, SEG Council, APEGA Executive, chair of the CSPG Honorary Address, and member of the GeoConvention Technical Committee. Throughout his career at Anderson Exploration, Devon Canada, BJV, with leadership roles at OptiSeis and SAExploration, he has pursued imaging improvements through innovative acquisition design, modeling, processing, and IFQC on seismic programs around the world. He has presented several times at GeoConvention, SEG Annual Meetings, and published papers in the CSEG Recorder. In addition to industry and volunteer positions, he is an avid musician who enjoys raising his two daughters and son.
 

SA/NT: Technical night & AGM

Monday, February 11, 2019
12:00
14:00

It is with great pleasure I write to invite you to our first technical event for the year- with the ASEG President Marina Costelloe from Geoscience Australia as our guest speaker, and a short AGM. 

The event will be held at the beautiful historic Ayers House, in the Ballroom. We will have a brief AGM followed by a presentation by Marina, “The Australian Society of Exploration Geophysicists: The President, Diversity and Science.” A cocktail lunch and drinks will be served with a small cost of $5 for members and students, and $15 for non-members. Please see more details in the attached PDF. Tickets need to be purchased on Eventbrite by Sunday 3rd February for catering purposes. Please contact me at sa-ntpresident@aseg.org.au with any dietary requirements or questions. 

This event coincides with International Women and Girls in Science Day, as such I take this opportunity to suggest you invite any women (or men) geoscientists who may like to come along to this event. 

Lastly, a friendly reminder to renew your ASEG membership if you haven’t yet. 

I look forward to seeing you on February 11th!

Kate Robertson 

ASEG SA/NT President 

SA/NT Student night & Christmas party

Tuesday, December 11, 2018
17:30
19:00

Three talks are on offer.

'Geology from geophysics' by Joel Stockill (Santos)

'A multi-method hydrological study of Wither Swamp in the Fleurieu Peninsula, South Australia', by Robin Keegan-Treloar (Flinders University)

'Constraining the regional slope of Western Papua New Guinea: A study of Lithospheric Flexure' by Michael Rieger (Adelaide University)

Food & drinks from 17:30 in the upstaris bar

Presentations from 18:15

Students & Members: Free

Non-members: $10

There is a prize for best dressed so come in festive atire.

The night is sponsored by Santos.

Please contact Kate Robertson for more details

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