# Subducting plate temperatures#

Before exploring the segments more, let’s briefly discuss temperature model for the subducting plates. The temperature structure of a slab can be quite complicated.

A model which was often used is a temperature structure from or based on the McKenzie temperature structure [7]. In the world builder this is implemented as the subducting plate temperature model called the `plate model`

Turcotte and Schubert [10]. If you want to use this, you will need to provide a reference density and a plate velocity like so:

```
1"temperature models":[
2 {"model":"plate model", "density":3300, "plate velocity":0.02}
3]
```

This is still perfectly valid and usable, but the approach has some fundamental issues, including that the way the temperature structure is set up is not mass conservative. This is why the `mass conserving`

slab temperature model was developed (Todo: insert reference when paper is done). This temperature model also brings a lot of other large and small improvements, which we can’t go over in this starter tutorial. Although this temperature is generally recommended over the older McKenzie model, it is also is a bit more complicated in usage. So to keep this tutorial simple, we will use the `plate model`

here, but we strongly recommend looking into the `mass conserving`

temperature model for subduction models.

Todo

Create a cookbook for the mass conserving temperature structure and point to it from here.

```
43 {
44 "model":"subducting plate", "name":"Slab", "dip point":[0,0],
45 "coordinates":[[1500e3,1000e3],[1600e3,350e3],[1500e3,0]],
46 "segments":[{"length":300e3, "thickness":[100e3], "angle":[0,60]}],
47 "temperature models":[{"model":"plate model", "density":3300, "plate velocity":0.02}],
48 "composition models":[{"model":"uniform", "compositions":[2]}]
49 }
50 ]
```

```
1{
2 "version": "0.6",
3 "coordinate system":{"model":"cartesian"},
4 "features":
5 [
6 {
7 "model":"mantle layer", "name":"upper mantle", "max depth":660e3,
8 "coordinates":[[-1000e3,0],[-1000e3,1000e3],[3000e3,1000e3],[3000e3,0]],
9 "composition models":[{"model":"uniform", "compositions":[4]}]
10 },
11 {
12 "model":"oceanic plate", "name":"Overriding Plate", "max depth":100e3,
13 "coordinates":[[0,0],[0,1000e3],[1500e3,1000e3],[1600e3,350e3],[1500e3,0]],
14 "temperature models":
15 [
16 {"model":"half space model", "max depth":100e3, "spreading velocity":0.04,
17 "ridge coordinates":[[[400e3,-1],[-100e3,2000e3]]]}
18 ],
19 "composition models":[{"model":"uniform", "compositions":[0], "max depth":50e3}]
20 },
21 {
22 "model":"continental plate", "name":"Passive margin", "max depth":[[200e3]],
23 "coordinates":[[-1000e3,0],[-1000e3,1000e3],[0,1000e3],[0,0]],
24 "temperature models":
25 [
26 {"model":"linear", "max depth":[[100e3],[200e3,[[-250e3,0],[-750e3,1000e3]]]]}
27 ],
28 "composition models":
29 [
30 {"model":"uniform", "compositions":[3],
31 "max depth":[[100e3],[200e3,[[-250e3,0],[-750e3,1000e3]]]]},
32 {"model":"uniform", "compositions":[1],
33 "min depth":[[100e3],[200e3,[[-250e3,0],[-750e3,1000e3]]]]}
34 ]
35 },
36 {
37 "model":"oceanic plate", "name":"Subducting Oceanic plate", "max depth":100e3,
38 "coordinates":[[2000e3,0],[2000e3,1000e3],[1500e3,1000e3],[1600e3,350e3],[1500e3,0]],
39 "temperature models":[{"model":"linear", "max depth":100e3}],
40 "composition models":[{"model":"uniform", "compositions":[3], "max depth":50e3},
41 {"model":"uniform", "compositions":[1], "min depth":50e3}]
42 },
43 {
44 "model":"subducting plate", "name":"Slab", "dip point":[0,0],
45 "coordinates":[[1500e3,1000e3],[1600e3,350e3],[1500e3,0]],
46 "segments":[{"length":300e3, "thickness":[100e3], "angle":[0,60]}],
47 "temperature models":[{"model":"plate model", "density":3300, "plate velocity":0.02}],
48 "composition models":[{"model":"uniform", "compositions":[2]}]
49 }
50 ]
51}
```