NT

NT Tech talk - Synchronous natural climate cycles of the Common Era, for Europe, China and globally – existence and implications for future temperature trends

Thursday, October 17, 2019
1600
1700

The talk can also be streamed to other members, if interested please contact one of the NT Division committee members.

 

Title: Synchronous natural climate cycles of the Common Era, for Europe, China and globally – existence and implications for future temperature trends

Author: Professor Michael Asten, School of Earth Atmosphere and Environment, Monash University. The talk summarises a joint effort with Kuan-Hui Elaine Lin (Univ of Taiwan) Carl Otto Weiss (PTB Braunschweig, Germany) Nicola Scafetta (Univ of Naples, Italy) and Alison Kelsey (U Qld), developed over three years at EGU 2017, 2018 and 2019.

 

Bio: Michael Asten is a Professor (retired) and ongoing Adjunct Senior Research Fellow in the School of Earth Atmosphere and Environment, Monash University, Melbourne.  He is a past-President of the ASEG, and served a recent three-year term as the AGC representative on the Australian Academy of Sciences UNCOVER Committee.  He has published 190 scientific papers.  He has developed passive seismic (microtremor) methods for 15 years, developing applications for earthquake hazard, and regolith characterization.   In the past six years he has applied signal processing methods to paleoclimate data sets with a view to quantifying past climate cycles and equilibrium climate sensitivity

 

Abstract:

We compare proxy temperature cycles contained in   data sets from European glaciation, China agricultural records, and two global proxy constructions.  A high correlation between European and China data sets, especially for 800-2000 CE, demonstrates a level of synchronicity beyond possible regional phenomena.  Spectral analysis shows a series of spectral peaks in all data sets consistent with those detected globally in cosmic ray flux, which supports the theory of natural climate cycles being partially under astronomical control. An interesting sidelight from the European and China data is observed temporal coincidence of social phenomena such as population decrease, starvation, disease and wars during phases of cooling, compared with human advancement during historical warmer phases. When the observed natural cycles are built into climate models, part of the global temperature increase of the past 170 years may be accounted for by natural cycles; we explore how this may influence estimates of climate sensitivity (the warming attributable to CO2 forcing for a doubling of atmospheric CO2).

 

Please don't hesitate to contact one of the NT Division committee members should you have any questions or wish to remote in for either presentation.

NT Tech talk - Comparisons of large igneous provinces (LIPs) and black shales in North China and Northern Australian cratons: Implications for paleogeographic reconstruction, paleoenvironment and subdivision of the geological time scale

Friday, September 27, 2019
1600
1700

The talk can also be streamed to other members, if interested please contact one of the NT Division committee members.

Title: Comparisons of large igneous provinces (LIPs) and black shales in North China and Northern Australian cratons: Implications for paleogeographic reconstruction, paleoenvironment and subdivision of the geological time scale

Author: Prof Zhang Shuanhong, Institute of Geomechanics, Chinese Academy of Geology

 

Bio: Shuan-Hong Zhang is a Professor of the Institute of Geomechanics, Chinese Academy of Geological Sciences and vice-director of Key Laboratory of Paleomagnetism and Tectonic Reconstruction, Ministry of Natural Resources in Beijing. His recent researches mainly focus on Meso-Neoproterozoic tectonics and paleogeographic reconstructions of the Nuna (Columbia) and Rodinia supercontinents using large igneous provinces (LIPs) and rifting sediments, as well as the potential environmental effect of LIPs during the Meso-Neoproterozoic period. During last 5 years, he has published over 12 scientific papers in international journals such as Geology, Earth and Planetary Science Letters, Earth-Science Reviews, Precambrian Research, Tectonics, etc., and obtained two key research funds from the National Natural Science Foundation of China to study the Meso-Neoproterozoic tectonics and correlations of the LIPs and black shales during the "Boring Billon (1800 to 800 Ma).

 

Please don't hesitate to contact one of the NT Division committee members should you have any questions or wish to remote in for either presentation.

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.