1 / 16

How do you teach ……?

How do you teach ……?. Partial Melting in different p late environments. Pete Loader 2011.

melania
Download Presentation

How do you teach ……?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. How do you teach ……? Partial Melting in different plate environments Pete Loader 2011

  2. GL4: Interpreting the Geological Record (WJEC specification)E1: Rock Forming Processes. Key Idea 1:Different environments and processes of magma formation and evolution generate different types of igneous rock.

  3. GL4: Q1 June 2010

  4. Partial melting Partial melting can be achieved when the temperature of the mantle (indicated by the local geotherm) exceeds the melting point of peridotite. This can occur in a number of ways and in different geological environments as shown by the following : • By adding water at a subduction zone (convergent boundary) – decreasing the mantle melting point. • By rapid decompression at a divergent boundary. • By locally increasing the geotherm (hot spot)

  5. No melting-normal situation Credit: Dougal Jerram Geotherm is below melting point curve for mantle peridotite (solidus)

  6. Melting by adding water Credit: Dougal Jerram Credit: U S Geological Survey Subduction zone By adding water at a subduction zone (convergent boundary) – decreasing the melting point of mantle peridotite (wet solidus)

  7. Student copy Student copy S Credit: http://geosun.sjsu.edu/~jmiller/Geo1_Lec5_IgRocks.html

  8. Rapid decompression melting Credit: Dougal Jerram Credit: U S Geological Survey Mid-Ocean Ridge Divergent plate boundary A rising convection current at a divergent boundary crosses the solidus and causing rapid decompression melting.

  9. Student copy Credit: http://geosun.sjsu.edu/~jmiller/Geo1_Lec5_IgRocks.html

  10. Partial melting at plate margins summary

  11. Past questions GL4: Q1 June 2003 GL4: Q4 June 2005

  12. Which igneous rocks typically form at plate boundaries? Basalt Andesite

  13. What is partially melting ? Credit: US Geological Survey

  14. Magmatic model at subduction zones 1. Partial melting of lithosphere subducted mafic crust, peridotite mantle wedge, continental crust 2. Gravity settling -Fractional crystallisation (cumulates) 3. Magma mixing 4. Contamination - Xenoliths Based on Loader et al .(in prep)

  15. EVALUATION In fact the processes of magma formation and evolution can generate igneous rocks with a variety of compositions regardless of the plate environment

  16. a good new book

More Related