Precambrian Geology HPP
HPP-01 General contributions to Precambrian geology Raimo Lahtinen, S. Wilde, J. Percival
The Precambrian represents a large part of Earth's history and encompasses the formation of the Earth, onset of plate tectonics, irreversible oxidation of atmosphere and hydrosphere to the evolution of complex multicellular organisms, including the first animals. There is still a controversy as to when modern-style plate tectonics started. Subduction-type processes probably operated already during Neoarchean or earlier but eclogites and UHP rocks are rare before the Neoproterozoic era. The exponential decline of Earth's radiogenic heat production has affected the formation and evolution of continental crust, lithospheric mantle and the style of plate interaction. Crustal growth is dominantly a Precambrian phenomena and the net crustal mass input from (Meso- )Neoproterozoic to present seems to be only 10-20% or less. The Archaean-Proterozoic transition is one of several critical intervals in Earth history when the terrestrial systems were experiencing rapid, global-scale changes seen as world-wide occurrences of glaciation, red beds and carbon isotope excursions. The role of Precambrian supercontinents Kenorland, Nuna, Columbia and Rodinia is very important in understanding the mantle dynamics, crustal growth and hydroatmospheric evolution of the Earth system. For this general symposium, we invite presentations of the field aspects, petrology, geochemistry, structural geology and isotope geology of Precambrian geology and presentations of models bearing on the evolution of Precambrian lithosphere.
HPP-04 From Rodinia to Nuna and beyond: Precambrian supercontinent reconstructions delving deeper in time Svetlana Bogdanova, David Evans, Mauro Cesar Geraldes, Hervé Théveniaut (IGCP 440 and IGCP 509)
Accurate descriptions of pre-Pangean paleogeographic reconstructions will be essential for understanding the role of supercontinents in mantle dynamics, as well as providing the boundary conditions for studies in global climate and hydroatmospheric chemistry of the evolving Earth system. Much recent work has advanced our perception of the Neoproterozoic supercontinent Rodinia, although some important questions remain unresolved. Rodinia's predecessor, the Paleoproterozoic supercontinent Nuna (or Columbia), is only beginning to take form. This symposium of the co-operating IGCP Projects 440 (Rodinia Assembly and Break-up) and 509 (Paleoproterozoic Supercontinents and Global Evolution) welcomes presentations of new tectonostratigraphic and paleomagnetic results bearing on Rodinia, Nuna, and earlier reconstructions, which are bound together both in their geological evolution and the methods we use to discover them.
HPP-05 Evolution of Archean crust Yildirim Dilek, Harald Furnes, Maarten de Wit
The role of plate tectonics in the evolution of Phanerozoic and Proterozoic crust is well established, but is a subject of debate regarding the Archean history. Crustal growth and differentiation through punctuated events (i.e. emplacement of mantle 'super-plumes') versus continuous subduction processes and whether Archean crust was too weak and mobile to behave as in rigid plates are fundamental questions in geodynamics. The occurrence of boninites, adakites, Mg-andesites, and ophiolites in some of the Archean greenstone belts suggests that Phanerozoic-like subduction zone tectonics may have been operating as early as 3.8 Ga. Specific questions to explore include the nature of magmatic and tectonic accretion of Archean continental crust and cratonization processes; sources of mantle magmatism; geodynamic evolution of greenstone belts, oceanic crust, and Archean ocean basins; and, the operation of plume activities and subduction processes in the Archean. This session is designed to evaluate the diverse dataset from the Archean rock record in order to address these questions and to better understand the nature and tempo of those processes involved in development of the Archean crust and their implications for the planetary evolution.
HPP-06 The evolving Earth system through Archaean-Palaeoproterozoic transition Victor A. Melezhik, David A.D. Evans, Ariel Anbar (IGCP509, ICDP FAR-DEEP, Kaapvaal Drilling Project, ABDP)
The Archaean-Proterozoic transition is one of several critical intervals in Earth history when the terrestrial systems were experiencing rapid, global-scale changes. The sequence of events includes the first global icehouse event, oxidation of the atmosphere and emergence of an aerobic world, and global perturbations in the carbon cycle, all representing the greatest challenge to life on Earth since its beginning. Overall, there is incomplete understanding of the timing, cause(s) and specifically the biological consequences with respect to the most profound change in surface environments during the early history of planet Earth. This session invites presentations of recent data and models bearing on the operation and interactions of various terrestrial systems leading to emerging modern-style geodynamics, irreversible oxidation of atmosphere and hydrosphere, drastic modification in ocean chemistry and isotope geochemistry, climatic instability and biological innovations including changes in C, S, P and N cycling. The invitation is also extended in to the understanding of extraterrestrial impacts on various terrestrial systems throughout this important period of Earth history.
HPP-07 Late Neoproterozoic orogenic belts and assembly of Gondwana Bernard Bingen, Joachim Jacobs, Alan S. Collins, Giulio Viola, Mark A. Smethurst, Daud Jamal Invited speakers: Sergei Pisarevsky, Alan Collins
Supercontinent Gondwana formed at the end of the Neoproterozoic, by assembly of Austral cratons, along Pan-African – Brasiliano orogenic belts. The Pan-African – Brasiliano system has multiple branches through Australia, India, Antarctica, Africa and South America, and qualifies as one of the largest orogenies that has affected planet Earth. Improved reconstruction of this orogenic cycle, and evaluation of its impact on Phanerozoic Earth history requires global and regional studies, integrating innovative geological mapping, stratigraphy, tectonics, geochronology, geochemistry, isotope geochemistry, petrology, geophysics, and paleomagnetism.
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