Topic G1 : ROCK FORMING PROCESSES Key Idea 2:The mineralogy and texture of metamorphic rocks are determined by the composition of the parent rock and the conditions of metamorphism Knowledge and Geological techniques Comments understanding and skills a. Igneous and sedimentary Analysis of simple pressure- Candidates should rocks contain minerals temperature-time paths appreciate that prograde that are stable or involved in contact and metamorphic effects result metastable at the regional metamorphism. from increases in temperature and temperature and (usually) pressure of their Simple analysis of phase pressure. Retrograde formation. Changes in diagrams showing stability metamorphism (though temperature and/or fields of selected metamorphic uncommon) allows directed stress over time minerals: kyanite/sillimanite/ prograde mineral lead to the growth of new andalusite. assemblages to revert to minerals with different those more stable at less stability fields. extreme temperature and pressure. Detailed knowledge of metamorphic facies is not required. b. Mineralogical changes SP20: Investigation of contact during metamorphism metamorphism using the depend on the ‘Metamorphic Aureole’ composition of the parent simulation experiment. rock and the temperature/pressure field. c. Contact and regional Candidates are expected to metamorphism of use evidence from index mudstone/shale lead to minerals to arrange clay- the growth of new rich rocks in order of their minerals indicative of the increasing grade. type and grade of metamorphism: low to high grade metamorphism. d. Contact, regional and Study of dynamic metamorphism diagrams/photomicrographs to result from different identify and analyse the pressure/temperature following metamorphic conditions and produce textures: granoblastic; characteristic textural porphyroblastic; mylonitic. changes associated with recrystallization, ductile flow and shear deformation.
Topic G1 : ROCK FORMING PROCESSES Key Idea 2:The mineralogy and texture of metamorphic rocks are determined by the composition of the parent rock and the conditions of metamorphism Knowledge and understanding Geological techniques and skills Comments a. Igneous and sedimentary rocks contain minerals that are stable or metastable at the temperature and pressure of their formation. Changes in temperature and/or directed stress over time lead to the growth of new minerals with different stability fields. Analysis of simple pressure- temperature-time paths involved in contact and regional metamorphism. Simple analysis of phase diagrams showing stability fields of selected metamorphic minerals: kyanite/sillimanite/ andalusite. Candidates should appreciate that prograde metamorphic effects result from increases in temperature and (usually) pressure. Retrograde metamorphism (though uncommon) allows prograde mineral assemblages to revert to those more stable at less extreme temperature and pressure. Detailed knowledge of metamorphic facies is not required. b. Mineralogical changes during metamorphism depend on the composition of the parent rock and the temperature/pressure field. SP20: Investigation of contact metamorphism using the ‘Metamorphic Aureole’ simulation experiment. c. Contact and regional metamorphism of mudstone/shale lead to the growth of new minerals indicative of the type and grade of metamorphism: low to high grade metamorphism. Candidates are expected to use evidence from index minerals to arrange clay- rich rocks in order of their increasing grade. d. Contact, regional and dynamic metamorphism result from different pressure/temperature conditions and produce characteristic textural changes associated with recrystallization, ductile flow and shear deformation. Study of diagrams/photomicrographs to identify and analyse the following metamorphic textures: granoblastic; porphyroblastic; mylonitic.
Geology%20Eduqas%20A%20level%20Guidance%20for%20Teaching%20word%20version.docx