Symposium themes and theme conveners:
1. Early Earth evolution: perspectives from the oldest minerals and rocks
The first half billion years of Earth’s history is the period when our planet attained its basic structure, permitting it to become habitable. However, assessing the geological record of this crucial period is a major challenge due to the lack of Hadean crust and the paucity of Eoarchean rocks, albeit assisted by the rare preservation of Hadean zircon crystals in younger rocks. This session will focus on unravelling the evolution of the early Earth by assessing evidence gleaned from the ancient geological record. Key issues include: 1) early planetary and proto-planetary evolution; 2) the timing of core–mantle and mantle–crust differentiation; 3) the nature and origin of Hadean and early Archean crust; and 4) interaction between early crust and oceans. We welcome new and exciting contributions on these and related topics.
Please note: The 6IAS would like to cross promote an Early Earth workshop and fieldtrip in honour and memory of Alfred Kröner. It is being run in South Africa on 13 – 23 November 2020. The workshop will focus on the evolution of the Archean central and eastern Kaapvaal Craton, South Africa, in order to commemorate the work of Alfred Kröner.
More information can be found here.
2. Emergence of atmosphere and life on early Earth and other terrestrial planets
Support systems for life on planetary systems begin and end with the environment, including the atmosphere. These may change over time and interact with a biosphere, once developed, leading to new niche space depending on the changes (temperature, composition, types and amounts of nutrients available) and on the style and rate of biological evolution. In this theme, we are interested in contributions that track key components, and the changing nature, of the atmosphere and environment of Earth through the Hadean–Archean, as well as the characteristics of other planetary systems both within and outside of our solar system, and how these may have changed over time.
3. Early Earth geodynamics: insights from geochemical, isotopic, phase equilibrium, and numerical modelling
At present, Earth’s mantle convection, which facilitates planetary heat loss, is expressed at the surface as plate tectonics. However, how and when plate tectonics emerged and evolved, and what, if anything, came before are among the most fundamental outstanding questions in Earth science. Given the scarcity of truly ancient rocks, increasingly sophisticated modelling techniques potentially provide the best opportunity to unravel early Earth evolution. We invite contributions that aim to better understand the dynamic evolution of Earth during the Hadean and Archean using geochemical, isotopic, phase equilibrium and numerical modelling.
4. The role of Archean lithosphere in the evolution of younger terranes
Isotopic analysis of crustal zircons indicates that approximately two-thirds of today’s crust is composed of Archean material. This is complemented by findings of Archean sub-continental lithospheric mantle beneath many younger crustal domains. Together, these findings suggest ancient lithosphere may be a far more important factor in the evolution of continents than generally perceived. We invite submissions that examine the presence, role and influence of Archean lithosphere on post-Archean terranes.
5. Cratons and craton margins: structure, composition and tectonic history
The lithospheric structure and crustal composition of Archean cratons suggest that each craton is unique, albeit sharing some common features. Understanding the processes that shape and modify Archean cratons and their margins is fundamental for unravelling how Earth’s continents have evolved. We invite contributions that utilize geophysical, geological and geochemical observations to address the structural and compositional evolution of cratons and their margins. We specifically encourage contributions that focus on less well-studied Archean cratons, for example in Russia, India, China, West Africa and South America.
6. Defining the Archean to Proterozoic transition
The transition from the Archean to the Proterozoic Eon marks a fundamental change in environments and processes on the early Earth. There is also a push to abandon the chronometric definition of the boundary at 2500 Ma, and establish a chronostratigraphic definition that will bring Precambrian stratigraphic nomenclature into line with the Phanerozoic, requiring the definition of a Global Boundary Stratotype Section and Point (GSSP). Candidates for defining the A-P boundary associated with global ocean and atmospheric evolution are the Great Oxidation Event and the Huronian Glaciation. An alternative proposal involves a transitional period, from 2600-2300 Ma, that records global changes in mantle rheology and chemistry. However, there is currently no consensus as to what event or proxy should be used to define the A-P boundary or at which location it should be defined. We call for papers that document changes in Earth systems that took place between the Neoarchean and Paleoproterozoic, particularly those relevant to the chronostratigraphic revision of the Precambrian timescale.
7. Mineral systems of Archean terranes and their margins
Archean mineral provinces are some of the richest on earth, containing a large range of mineral deposit types and commodities: orogenic gold, komatiite-associated nickel (Ni–Cu–Co–PGE), volcanic-hosted massive sulfide (Cu–Zn–Pb–Ag–Au) and iron ore deposits are the most important. This Symposium aims to discuss: 1) multi-scale processes in the formation of Archean mineral systems, ranging from the role of lithospheric-scale tectonics to processes and geological features that control ore localisation at the deposit- to province-scales; 2) the development and nature of mineral system within the changing geodynamic evolution of the early Earth; and 3) how (or whether) pre-existing Archean lithospheric architecture may have played a part in localising younger mineralisation.
More information and a detailed program TBA – please check back soon.