Theme: Geochemistry and Petrology

Africa: A Mecca of Kimberlite, Alkaline Rock and Carbonatite Geology

Convenors: Prof. Anatoly Zaitsev; Prof. Anton Chakhmouradian; Dr. Ekaterina Reguir

Description:
Africa is well known to anyone studying mantle-derived magmas, as well as xenoliths and xenocrysts (think diamonds!) transported by these magmas. Many seminal works on the geology and economic potential of kimberlites and carbonatites were based on the classical localities of these rocks in South Africa and the East-African Rift, and many paradigm-shifting ideas regarding the petrogenesis of these and related rocks were precipitated on this continent. Africa is home to the world's only carbonatite volcano and first kimberlite mine, not to mention a slew of wonderful alkaline rocks that were discovered here (like phoscorites, katungites, etc.). It is on this continent where the earliest evidence of hominid bipedalism has been preserved thanks to... carbonatite eruptions, a connection to human evolution we are just beginning to understand. The proposed session will highlight the most recent developments in our understanding of carbonatites, kimberlites, alkaline rocks, their genesis, and economic potential.

Keynote Presenter: Prof. Roger Mitchell

 

Aqueous and Carbonic Fluids in Ultramafic Rocks: From Vein Precipitation to Channeled and Pervasive Wall-Rock Reaction

Convenors: Prof. Walter Maresch; Dr. Hans-Peter Schertl; Prof. George Harow

Description:
Aqueous and carbonic fluids flowing through, reacting with and precipitating in ultramafic rock sequences can leave records of their passage in the form of very distinctive rock types, such as jadeitite, nephrite, rodingite, sagvandite, listvenite, etc.. Some, such as jade, have been of cultural significance for more than 5000 years, not only due to their beauty but also their useful physical properties. Some, such as listvenites, have been helpful as indicators of ore deposits. In situ "blackwall" shells are classical text-book examples of local mass transport. However, in many cases the details surrounding this fluid-related origin are still debated. Unclear nomenclature impedes an organized discussion. This symposium seeks to shed light on this heterogeneous group of rocks by promoting a systematic mineralogical and petrological assessment. What can the rocks tell us about the aqueous and carbonic fluids in various geological settings ranging from the depths of subduction-zone channels to near-surface fault systems?

 

Crystal-chemistry of light elements in rock-forming minerals 

Convenors: Dr. Jean-Louis Robert

Description:
Light elements, from H to F, present a peculiar interest in many rock-forming minerals either as major or as trace components, i.e. hydrogen. Unusual substitutions and coordination numbers of light elements are more and more frequently observed and reflect specific genesis conditions at crust, mantle and deeper level, in major mineral families as well as "exotic" phases. All aspects will be considered: mineralogy, crystallography, analytical and spectroscopic approaches (vibrational, NMR, ...), and ab initio calculations.

 

Dating Metamorphic Processes: Promise and Pitfalls of Geochronology

Convenors: Dr. Hao Cheng; Dr. Tatsuki Tsujimori; Prof. Patrick O'Brien; Dr. Hafiz UrRehman

Description:
The advent of high-precision isotope analysis by state-of-the-art facilities, such as MC-ICP-MS, HR- SIMS and SHRIMP, has led to unprecedented age resolution for various minerals. Our ability to routinely measure diverse isotope systems, such as zircon U-Pb, garnet Lu-Hf and Sm-Nd isotopes, enhances our understanding of the geodynamics of the metamorphic rocks. However, applications of these data can be limited by challenges in interpreting the petrologic record and the target minerals for analysis. We welcome a broad spectrum of contributions such as improved dating methods, innovations in the geochronology of major rock forming minerals as well as accessory phases, advances in data acquisition and interpretation of linking to metamorphic processes and provenance studies. The aim of the session is to explore what is new now and what new methods, and what are the promise and pitfalls of geochronology in dating metamorphic processes.

Keynote Presenter: Prof. Thomas J Lapen

 

Geologic Fluids in the Deep Crust and Upper Mantle

Convenors: Prof. Dirk van Reenen – IMA Working Group on Mineral Equilibria; Prof. Leonid Aranovich; Prof. Oleg Safonov; Prof. Daniel Harlov

Description:
Complex multi-component fluids are widely involved in a variety of endogenic processes both in the Earth's crust and mantle. This session will focus on the interplay between natural observations, laboratory experiments and theoretical studies. Presentations devoted to physicochemical properties of crustal fluids, such as the composition, miscibility ranges, composition-activity relations, experimental data on fluid-mineral equilibria and reactions at crustal and upper mantle conditions, and data on the impact of fluids on rheological properties of crustal rocks, including mechanisms of pervasive intergranular fluid flow through hot ductile rocks as compared to channelized fluid flow, are welcomed. Of special interest to the session is evidence for a genetic link between crustal and upper mantle fluids. This interdisciplinary session thus solicits all types of contributions related to petrological, geochemical, and experimental evidence for the activity of fluids during high-grade metamorphism in the lower and middle crust, as well as in the Earth's upper mantle.

Keynote Presenter:  Dr. James A.D. Connolly (Geochemistry Group, ETH Zentrum, Zurich)
Keynote Presentation:  The permeability of the impermeable lower crust

 

Magma Differentiation and Ore Formation Process

Convenors: Dr. Ilya Veksler; Dr. Rais Latypov; Dr. Jakob Keidling

Description:
The origin of magmatic layering, mechanisms of strong concentration of accessory minerals and trace elements in plutonic rocks, and formation of magmatic ore deposits remain among the major unresolved problems of igneous petrology. The problems are not only of great academic interest but also of practical importance for mining and industrial ore processing. Recent progress in understanding of plutonic systems and related mineralization has been achieved through a synthesis of multidisciplinary studies. This session aims at bringing together researchers who study igneous rocks by field observations, textural analysis, computer simulations, mineralogical, geochemical, experimental and geophysical methods. Contributions on all aspects of magma chamber processes and magmatic ore deposits are welcome.

 

Magmas and Melts Under Extreme Conditions

Convenors: Prof. Grant Henderson - CPM; Mr. Daniel Neuville; Mr. Roberto Moretti

Description:
The purpose of this session is to understand multiphase magmatic properties, structure, and physicochemical and thermodynamic properties of silicate melts and glasses, under extreme conditions. The ability to study these types of geological materials in-situ at high temperatures and pressure is becoming increasingly routine. This session solicits submissions that involve any aspect of magmas or melts under extreme conditions such as high temperature and pressure. We strongly encourage the submission of contributions focusing on:

i. melt/glass mixing properties,
ii. spectroscopic evidence for short and medium range structure,
iii. the role of cationic and anionic interactions on transport properties,
iv. volatile solubility and diffusivity,
v. speciation behaviour of elements, with emphasis on volatiles and trace elements
vi. redox properties and the structural role of transition elements,
vii. the glass transition,
viii. rheological properties of magmas, with emphasis on both melt and multiphase systems showing complex rheology,
ix. Experimental and computational determination of phase relations, particularly in volatile-bearing systems, and their impact for the study of magma properties.
x. ab initio modelling of melts and advances in analytical and spectroscopic techniques.

Finally, applications to both natural magmas and glasses, as well as to industrial processes, will be most welcome.

Keynote Presenter: Harald Behrens

 

Magma mixing - from macro to micro scale 

Convenors: Prof. Ewa Slaby; Dr. Diego Perugini

Description:
Magma mixing is a process of fundamental importance in the Earth system. Understanding its development, both in space and time, is crucial for understanding the genesis of igneous rocks. From a petrological point of view, investigation of the interaction between magmas is of utmost for deciphering the chemical composition of the end-member primary melts, the latter often essential for constraining tectonic settings. From a volcanological point of view, the replenishment of a sub-volcanic magma reservoir is one of most important processes triggering explosive eruptions. Although increasing natural evidence indicates magma mixing as a major petrological process in the Earth system, several questions still remain open. Among them: which rheological conditions promote or inhibit mixing processes? What is the spatial and temporal compositional variability of igneous systems affected by magma mixing processes? How do geochemical heterogeneities produced by mixing processes influence the composition and textures of crystallizing minerals? What are the time-scales for magma mixing and hybrid melt production? This session invites contributions on the structural (field relations), textural (zoning, resorption, chemical and isotopic disequilibrium in minerals), and geochemical (major and trace elements and isotopes) study of magma mixing in both the plutonic and the volcanic setting. Contributions targeting the study of magma mixing by experimental, theoretical and numerical modelling are also welcome.

Keynote Presenter: Prof. Gerhard Wörner
Keynote Presentation: Uniform components and mixing regimes in magma systems of the Central Andean Volcanic Zone

 

Mineral Inclusions - Their Genesis and Fate

Convenors: Dr. Alexander Proyer; Mr. Tzen-Fu Yui; Prof. Shah Wali Faryad

Description:
This session invites any kind of interesting contribution about crystalline inclusions in minerals, but particularly those that deal with the post-entrapment alteration of primary inclusions (and their hosts), the formation of crystallographically oriented inclusions and their possible ways of formation, as well as the consequences of such observations for geothermobarometry, geochronology and our general understanding of reaction mechanisms, effective bulk compositions and geological scenarios.

Keynote Presenter:  Dr. Alexander Proyer
Keynote Presentation: Formation and alteration of primary and secondary mineral inclusions: field examples and their interpretation and geological relevance

 

Petrologic Pathfinders: Trace Elements and Stable Isotopes in Tourmaline, Rutile and Other Accessory Minerals

Convenors: Dr. Robert Trumbull; Dr. Horst Marschall

Description:
Accessory minerals are key for our understanding of the geochemical evolution of the lithosphere, as they dominate the rock budgets of trace elements in many rocks and are invaluable archives of the geochemical and geochronological history of magmatic, metamorphic and sedimentary rocks and ores. Through modern in-situ analytical methods progress is made in unravelling the growth history stored in individual grains or even sub-grain domains. This session invites contributions from studies into the major and trace-element chemistry, inclusion population, geochronology, crystallography and isotopic composition of accessory phases, such as tourmaline, rutile, apatite and zircon. Our focus is on studies that investigate these data in the context of the magmatic, metamorphic or hydrothermal systems that formed the host rocks of the accessory minerals, and employ them as monitors of the P-T-X histories of the systems. The refinement of our ability to read these archives opens the way to heavy minerals in sediments being employed to reconstruct geodynamic processes for episodes where the crystalline rock record is sparse, such as the early Precambrian.

 

The Geology of Gems and their Geographic Origin

Convenors: Mr. Gaston Giuliani; Prof L Groat; Mr. D. Ichangi (IMA Commission on Gem Materials)

Description:
Understanding where, when, how and why gem deposits formed is important from more than an academic perspective. The genetic models provide guidelines for exploration, give conceptual understanding, and help to forecast the location of undiscovered gem deposits. The geochemical and isotopic fingerprints of coloured mineralogical and gemmological data are validated by experiments. The session will cover all aspects related to high value coloured gems: crystallography of gemstones primarily sheds light on their geological and sometimes their geographical occurrence. During the past two last decades, knowledge on the formation of these gem deposits has improved significantly with scientific discoveries. The finding of world class gemstone deposits is an essential challenge for the industry but what are the new challenges in the study of high value gemstones? The main question is how can we explain scientifically the known unknowns of the 4C's criteria used in gemstone grading (Clarity, Colour, Carat and Cut)? Another is why do minerals sometimes become gems? This question would be answered by integrating geological, mineralogical and gemmological data validated by experiments. The session will cover all aspects related to high value coloured gems: crystallography, geochemistry (major and trace elements, stable and radiogenic isotopes, radio-isotope dating), tectonic and structural setting, and genesis. It is envisaged that attaching sound scientific information to such well-known gemstone belts as the Neoproterozoic Metamorphic Mozambican belt, the Himalayan Belt and the Cenozoic basaltic alkaline and sedimentary provinces will result in improved understanding of geologic settings and formation conditions. 

 

Timing and Genesis of Mineralizations: The Isotope Record

Convenors: Dr. Axel Gerdes; Prof. Dirk Frei

Description:
From the formation of massif ore deposits to small scale weathering, most mineralizations formed as reactions between fluids and rocks at various temperatures and tectonic settings. Besides the timing and processes involved, the origin of fluids, temperature, and mobilized elements is in many cases not well understood. Radiogenic and staple (conventional and non-conventional) isotopes have been successfully applied in the recent years to date mineralization, to link it to certain magmatic and metamorphic processes, to characterize the fluid, the physic-chemical conditions, and the processes involved, as well as to identify the source of the elements, which have been enriched. This session aims to unit research applying different kind of isotope methods to study fluid-rock interactions and various types of mineralizations; to emphasize the potential of the isotope record for the understanding of ore formation and to stimulate new research.

Keynote Presenter: Dr. Armin Zeh
Keynote Presentation: Crystallisation of the Rustenburg Layered Suite (Bushveld Complex) within less than 1.5 million years - constraints from CA-ID-TIMS dating, geothermometry, and inclusions in zircon
 

Pegmatites and pegmatite mineralogy 

Convenors: Prof. Robert Martin McGill, Prof. William 'Skip' Simmons; Dr. Paul Nex

Description:
Pegmatites and their mineralogy are of major interest to many diverse groups of geologists. This session is envisaged as an opportunity for presentations covering aspects of pegmatite genesis, classification, petrology and mineralogy. There is still considerable debate regarding the source(s) of pegmatites, the role of fluids and volatiles, and the processes resulting in the concentration of highly incompatible elements. Pegmatites are one of the main sources of various gemstones, they frequently contain a wide variety of rare and unusual minerals, and are also major sources for several commodities including tantalum, uranium, lithium, mica and feldspar. African pegmatites are no exception to this, and this session will provide a forum for some of the more recent studies on the continent. Two field trips associated with IMA 2014, (Pan-African pegmatites in Namibia and in Madagascar) provide an opportunity for this to be a scientific session integrated and stimulated by field-based observations.

 

General Session - Geochemistry and Petrology 

Convenors: Dr. Paul Nex

Description:
This is a general session under the theme of geochemistry and petrology for submission of abstracts that do not conform with other sessions under this theme.