Plate Boundaries and Igneous Activity Overview

1. A summary of plate boundaries and igneous activity

2. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Constructive OP Oceanic ridge Constructive CP Destructive CP-OP Destructive OP-OP Destructive CP-CP Conservative

3. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge Constructive OP East African Rift Valley Rift valley, normal fault scarps Constructive CP Basalt lavas Destructive CP-OP Destructive OP-OP Destructive CP-CP Conservative

4. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge East African Rift Valley Rift valley, normal fault scarps Basalt lavas Constructive OP Constructive CP Ocean trench, fold mountain range Andes mountains Andesitic lavas Destructive CP-OP Destructive OP-OP Destructive CP-CP Conservative

5. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge East African Rift Valley Rift valley, normal fault scarps Basalt lavas Constructive OP Constructive CP Ocean trench, fold mountain range Andes mountains Andesitic lavas Destructive CP-OP Ocean trench, island arc Aleutians, Phillipines Andesitic lavas Destructive OP-OP Destructive CP-CP Conservative

6. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge East African Rift Valley Rift valley, normal fault scarps Basalt lavas Ocean trench, island arc Aleutians, Phillipines Andesitic lavas Constructive OP Constructive CP Ocean trench, fold mountain range Andesitic lavas Destructive CP-OP Andes mountains Destructive OP-OP Large granitic batholiths Destructive CP-CP Fold mountains Himalayas Conservative

7. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge East African Rift Valley Rift valley, normal fault scarps Basalt lavas Ocean trench, island arc Aleutians, Phillipines Andesitic lavas Constructive OP Constructive CP Ocean trench, fold mountain rge Andes mountains Andesitic lavas Destructive CP-OP Destructive OP-OP Large granitic batholiths Destructive CP-CP Fold mountains Himalayas San Andreas Fault Conservative Fault zone None

8. Mid Atlantic Ridge, East Pacific Rise Basalt lavas – pillows (spilites – Na rich) Oceanic ridge East African Rift Valley Rift valley, normal fault scarps Basalt lavas Ocean trench, island arc Aleutians, Phillipines Andesitic lavas Constructive OP Constructive CP Ocean trench, fold mountain range Andes mountains Andesitic lavas Destructive CP-OP Destructive OP-OP Large granitic batholiths Destructive CP-CP Fold mountains Himalayas San Andreas Fault Conservative Fault zone None

9. Key points : Different environments and processes of magma formation generate different types of igneous rocks ie. melting of rock material at depth generates magmas within a number of different plate environments

10. AND : • Partial melt of mantle rocks beneath CONSTRUCTIVE PLATE MARGINS generates BASALTICmagma; • Near to DESTRUCTIVE PLATE MARGINSpartial melt in and above the subductive oceanic lithosphere generates ANDESITIC magma; • In mantle hot spotspartial melt of mantle rocks above a mantle plume generates ANDESITIC magma; • In deeply buried lower CONTINETAL CRUST during orogenies – melting of crust generates GRANITIC/ACIDIC/SILICICmagma.

11. Task : Using PHYSICAL GEOLOGY – Plummer & McGeary 1. Read Ch18 and Ch19 2. Ch 19 - Make additional notes and your own diagrams eg 19.12, 19.13, 19.20, 19.22, 19.26, 19.29. 3. Make notes on : Causes of plate motion p441; Mantle plumes p443; A cautionary note p445 and Summary p448 3. Be able to define all the “terms to remember on p448. Take PHYSICAL GEOLOGY home and use it for extra reading/note making. Start with Ch1 and 2 !!