Welcome This is a document to explains the chosen concept to the animator. This will take you through a 5 section process to provide the necessary details to the animator before starting the animation. The legend on the left will indicate the current status of the document. The big Black coloured number will denote the current section, the Grey color would denote the completed sections, and the Turquoise color would denote the remaining sections. The slides having yellow background (like this one) are the 'Instruction slides'

Subduction Mechanism Subduction zones exist at convergent plate boundaries where one plate of oceanic lithosphere converges with another one. The down-going slab- the subducting plate- is overridden by the leading edge of the other plate. The overriding continental plate is lifted up, and a mountain range is created. The oceanic plate bends and plunges steeply through the asthenosphere. Sinking of the oceanic plate due to contrast of density between the cold and old lithosphere and the hot asthenospheric mantle wedge, is one of the strongest forces needed to drive the plate and is the dominant mode of mantle convection.  Related LOs: > Prior Viewing: Plate tectonics/ Movement > Future Viewing :  Course Name: Plate Tectonics Level: Post graduation  Author: Arpita Roy  Mentor: Prof. Soumyajit Mukherjee *The contents in this ppt are licensed under Creative Commons Attribution-NonCommercial-ShareAlike 2.5 India license

Learning objectives After interacting with this Learning Object, the learner will be able to: Describe the geological phenomenon in the Subduction zone

Master layout or diagram Make a schematic diagram of the concept Explain the animator about the beginning and ending of the process. Draw image big enough for explaining. In the image, identify and label different components of the process/phenomenon. (These are like characters in a film) ‏ Illustrate the basic flow of action by using arrows. Use BOLD lines in the diagram (minimum 2pts.) ‏ In the slide after that, provide the definitions of ALL the labels used in the diagram You may have multiple master layouts. In this case, number the master layout. (e.g. Master layout 1, 2, 3…) ‏

Keywords/Definitions Converging continental plate: In plate tectonics, a convergent boundary, also known as a destructive plate boundary, is an actively deforming region where two (or more) plates or fragments of lithosphere move toward one another and collide. As a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries. Accretionary wedge : An accretionary wedge or an accretionary prism is formed from sediments that are accreted onto the non- subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the down going slab of oceanic crust, but in some cases includes the erosional products of volcanic island arcs formed on the overriding plate. Forarc basin: A forearc or forarc, also called arc-trench gap, is a depression in the sea floor located between a subduction zone and an associated volcanic arc. It is typically filled with sediments from the adjacent landmass and the island arc in addition to trapped oceanic crustal material

Keywords/Definitions Magmatic arc or Volcanic arc: This is a result of the subduction of an oceanic tectonic plate under another tectonic plate, and often parallels an oceanic trench. The oceanic plate is saturated with water, and volatiles such as water drastically reduces the melting point of the mantle. As the oceanic plate is subducted, it is subjected to progressively increasing pressures with increasing depth. This pressure squeezes water out of the plate and introduces it to the mantle. Here the mantle melts and forms magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone Back arc basin: These are submarine basins associated with island arcs and subduction zones. This is the region landward of the volcanic chain on the other side from the subduction zone Convergence: Convergence is a phenomenon in which, two plates come together and one plate will be going downward respect to the another one.

Oceanic plate Mantle (asthenosphere) Trench Continental crust Volcano Mantle lithosphere Magma ascension Oceanic crust Master layout: 1 Fig. 1 Volcanic arc In our considerable phenomenon, subduction process involves the convergence between the oceanic plate and continental plate and results volcanic arc

Island arc Asthenosphere Lithosphere Trench Fig. 2 Master layout: 2 Oceanic plate Continental plate Oceanic plate The blocked portion involves the uprising magma (shown by black arrow) In our considerable phenomenon, subduction process involves convergence of oceanic and oceanic plate and results Island arc

Explain the process In this step, use an example to explain the concept. It can be an analogy, a scenario, or an action which explains this concept/process/topic Try to use examples from day-to-day life to make it more clear You have to describe what steps the animator should take to make your concept come alive as a series of moving images. Keep the examples simple to understand, and also to illustrate/animate

Analogy Description of the event in brief: The two solid slabs are subjected to head-on collision but due to density difference, one slab goes down under the second one, which results in the formation of different tectonic features. Analogy of the above said event: Scraping of a cream cake with a knife is analogous to the formation of accretionary prism and fore arc basin

Stepwise description of process The goal of the document is to provide instructions to an animator who is not a expert. You have to describe what steps the animator should take to make your concept come alive as a moving visualization. Use one slide per step. This will ensure clarity of the explanation. Add a image of the step in the box, and the details in the table below the box. You can use any images for reference, but mention about it's copyright status The animator will have to re-draw / re-create the drawings Add more slides as per the requirement of the animation

Oceanic plate Mantle (asthenosphere) Trench Continental crust Volcano Mantle lithosphere Magma ascension Oceanic crust Step: 1, Volcanic arc formed by oceanic-continental subduction Fig. 1 Description of the actionAudio narrationText to be displayed 1)Show that the oceanic plate is going towards downward direction (as shown by black arrows) 2)The down-going oceanic plate makes an angle with the mantle lithosphere (almost 45 ⁰ ) 3)Show the magma (shown by orange colour) is going upwards by black arrow and forms volcanic arc ( denotes by area little bit elevated) 4)Time duration for this event will be seconds In our considerable phenomenon, subduction process involves the convergence between the oceanic plate and continental plate and volcanic arc is the resultant event. Volcanic arc

Island arc Asthenosphere Lithosphere Trench Fig. 2 Step: 2, Island arc formed by oceanic-oceanic subduction Description of the actionAudio narrationText to be displayed 1)Show the lithospheric oceanic plate: 1 is going downward (as shown by yellow arrows) 2)Another oceanic lithospheric plate : 2 is coming above the former one (shown by green arrows) 3)Show the uprising (shown by black arrow) magma (by red colored material) which results island arc 4)Time duration for this event will be seconds In our considerable phenomenon, subduction process involves convergence of oceanic and oceanic plate. Island arc is the resultant event. Oceanic plate: 1 Continental plate Oceanic plate: 2 The blocked portion involves the uprising magma (shown by black arrow)

Animation design Please see the design template provided in the next slide. This is a sample template, and you are free to change as per your design requirements. Try and rename the tabs / buttons / sections / subsections as shown in the template. Use ‘callouts’ as shown above to explain the source of content. Ex: If the call out is placed at the Tab 01, and you want the content to be taken from slide 3 of this presentation, then place this callout on the Tab 01, and write ‘Slide 3’ inside the callout. Slide

Animation design First show the movement of the oceanic plate. Then after, the movement of magma ascension. Both of these activities Will take seconds. Credits Interactivity area Start Replay Model 1 Summary Definitions Model 2 Mantle (asthenosphere) Oceanic crust Trench Continental crust Magma ascension Volcanic arc Volcano Oceanic plate Fig

Animation design First show the downward movement of the oceanic plate: 1 ( shown by yellow arrow), then after overriding movement of the oceanic plate: 2( shown by green arrow) over the oceanic Plate: 1. Show the uprising movement of the magma (red triangular portion) and finally the formation of Island arc. The Time duration for whole event will be seconds. Credits Interactivity area Start Replay Model 1 Model 2 Summary Definitions Asthenosphere Oceanic plate: 1 Lithosphere Oceanic plate: 2 Continental plate Island arc Trench Fig

Self- Assessment Questionnaire for Learners Please provide a set of questions that a user can answer based on the LO. They can be of the following types: – These questions should be 5 in number and can be of objective type (like MCQ, Match the columns, Yes or No, Sequencing, Odd One Out). – The questions can also be open-ended. The user would be asked to think about the question. The author is requested to provide hints if possible, but a full answer is not necessary. – One can include questions, for which the user will need to interact with the LO (with certain parameters) in order to answer it. – It is better to avoid questions based purely on recall. APPENDIX 1

Questionnaire : 1) How would be thermal structure of the down going slab during subduction process? a) As it going towards depth, the temperature increases b) Temperature would not vary c) Temperature will decrease d) Temperature does not matter with the distance of the down going slab 2) What is the angular relation between the down going plate with respect to the uppermost layer of the Earth? a) 0 ⁰ b) 45 ⁰ c) 90 ⁰ d) 60 ⁰ APPENDIX

Questionnaire: 3) In case of subduction which portion (the portion of Earth) will go down and why? a) Asthenosphere, as it becomes more denser b) Lithosphere, as it becomes cool and more denser c) Lithospheric plate, due to overburden pressure d) None of these. 4) What are reasons behind the rising of mid oceanic ridge or its topographic elevation? a) Due to buoyancy of the thinner lithospheric plate b) The body force created by the oceanic ridge helps the plates to move away from the ridge area c) Ridge push or gravitational force helps mid oceanic ridge to go upwards or elevate d) All of these

Links for further reading In the next slide, provide some reference reading material for the users. It could be books, reference publications, or website URLs. APPENDIX 2

Links for further reading APPENDIX

Summary Please provide points to remember to understand the concept/ key terms of the animation, in the next slide. The summary will help the user in the quick review of the concept. APPENDIX 3

Summary APPENDIX 3 At the mid-oceanic ridge, new plates pushes the older oceanic plate. The oceanic plate dives under the continental plate and scraps against the continental plate forming the accretionary wedge. The subducting plate continues to go below the over-riding plate, and the convection currents pulls the slab. Due to high friction between the plates, the continental plate buckles up. The accretionary prism continue to rise and forms a fore arc basin. Partial melting of subducting plate provides the molten material for magmatic arc and for spreading axis of the back arc basin.