SOUTH AMERICA

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006699" TEXT="#080000" background="0a9fd5a3.jpg"> <div> <FONT SIZE="6" COLOR="#FF0000" FACE="Arial" ><B><IMG SRC="0b1c52d0.gif" border=0 width="197" height="45" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></FONT><B>    </B><B> |     </B><A HREF="index.htm" TARGET="_top" TITLE=" "><U><B>home</B></U></A><B>                                                          </B><FONT SIZE="7" COLOR="#FF0000" FACE="Arial" ><B>AstroGeoData</B></FONT></div> <div> <A HREF="id69.htm" TARGET="_top" TITLE="EUROPE"><U>EUROPE</U></A>   |   <A HREF="id70.htm" TARGET="_top" TITLE="ATLANTIC"><U>ATLANTIC</U></A>   |   <A HREF="id71.htm" TARGET="_top" TITLE="NORTH AMERICA"><U>NORTH AMERICA</U></A>   |   <A HREF="id112.htm" TARGET="_top" TITLE="CENTRAL AMERICA"><U>CENTRAL AMERICA</U></A>   |   <B>SOUTH AMERICA</B>   |   <A HREF="id73.htm" TARGET="_top" TITLE="AFRICA"><U>AFRICA</U></A>   |   <A HREF="id111.htm" TARGET="_top" TITLE="INDIAN OCEAN"><U>INDIAN OCEAN</U></A>   |   <A HREF="id75.htm" TARGET="_top" TITLE="ASIA"><U>ASIA</U></A>   |   <A HREF="id76.htm" TARGET="_top" TITLE="NORTH PACIFIC"><U>NORTH PACIFIC</U></A>   |   <A HREF="id77.htm" TARGET="_top" TITLE="SOUTH PACIFIC"><U>SOUTH PACIFIC</U></A>   |   <A HREF="id264.htm" TARGET="_top" TITLE="AUSTRALIA"><U>AUSTRALIA</U></A>   |   <A HREF="id78.htm" TARGET="_top" TITLE="ARCTIC"><U>ARCTIC</U></A>   |   <A HREF="id87.htm" TARGET="_top" TITLE="ANTARCTIC"><U>ANTARCTIC</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#BBBBBB" TEXT="#080000" background="0aad2043.jpg"> <div>         <FONT SIZE="2" COLOR="#FF0000" FACE="Arial" ><A HREF="id29.htm" TARGET="_top" TITLE="DATA"><U><B>Back to DATA</B></U></A></FONT></div> <bR> <div> <FONT SIZE="2" COLOR="#FF0000" FACE="Arial" ><B>       </B></FONT><B> </B><A HREF="id46.htm" TARGET="_top" TITLE="EARTHQUAKES"><U><B>Earthquakes</B></U></A><A HREF="id46.htm" TARGET="_top" TITLE="EARTHQUAKES"><U><B> </B></U></A><B>   </B><FONT SIZE="2" COLOR="#FF0000" FACE="Arial" ><B> </B></FONT></div> <div> <B>     </B></div> <div> <B>             </B></div> <div> <B>     </B></div> </td> <td valign="top" height=390 BGCOLOR="#DDDDDD" TEXT="#080000"> <div> <I><B>SOUTH AMERICA</B></I></div> <bR> <div> <IMG SRC="28879900.jpg" border=0 width="377" height="400" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <bR> <bR> <div> <B>General Geological Setting</B></div> <bR> <bR> <div> <IMG SRC="3bf307a0.jpg" border=0 width="560" height="890" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <div> <TABLE BORDER="0" CELLPADDING="1" CELLSPACING="1" WIDTH="626" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="NONE" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="622"><div> <B>PLATES ARE DESTROYED (SUBDUCTION):</B> </div> </tD> </tR> </TABLE></div> <bR> <div> <TABLE BORDER="0" CELLPADDING="1" CELLSPACING="1" WIDTH="683" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="NONE" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=CENTER HEIGHT= 144 ><NOBR><div> <IMG SRC="3c2588a0.gif" border=0 width="344" height="138" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP WIDTH="310"><bR> <bR> <bR> <bR> <bR> </tD> </tR> </TABLE></div> <bR> <div> This is a <B>convergent plate boundary</B>, the plates move towards </div> <div> each other. </div> <div> The amount of crust on the surface of the earth remains relatively </div> <div> constant. Therefore, when plates <B>diverge</B> (separate) and form </div> <div> new crust in one area, the plates must <B>converge</B> (come together) </div> <div> in another area and be destroyed. An example of this is the Nazca </div> <div> plate being subducted under the South American plate to form the </div> <div> Andes Mountain Chain.</div> <bR> <bR> <div> <TABLE BORDER="0" CELLPADDING="1" CELLSPACING="1" WIDTH="626" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="NONE" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=CENTER HEIGHT= 336 ><NOBR><div> Here we can see the oceanic plate moving from left to right. </div> <div> The top layer of the mantle and the crust (all called the lithosphere) </div> <div> sinks beneath the continent. A deep ocean trench is formed. </div> <div> Water gets carried down with the oceanic crust and the rocks begin </div> <div> to heat up as they travel slowly into the earth. Water is then driven off </div> <div> triggering the formation of pools of molten rock which slowly rises. </div> <div> The plate moves downwards at a rate of a few centimetres per year. </div> <div> The molten rock can take tens of thousands of years to then either<B>:</B> </div> <bR> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Solidify <B>slowly</B> underground as <B>intrusive igneous rock</B> </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">such as granite<B>.</B> </div> <bR> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">or</div> <bR> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Reach the surface and erupt as lava flows. Cooling <B>rapidly</B> to </div> <div> form <B>extrusive igneous rock</B> such as basalt.</div> <bR> <div>  </div> </NOBR></tD> </tR> </TABLE></div> <div> The floor of the Easter Pacific is moving towards South America at </div> <div> a rate of 9 centimetres per year. It might not seem much but over </div> <div> the past 10 million years the Pacific crust has been subducted under </div> <div> South America and has sunk nearly 1000 kilometres into the Earth's </div> <div> interior.</div> <bR> <bR> <bR> <div> <B>EARTHQUAKES</B></div> <bR> <div> <A HREF="id220.htm" TARGET="_top" TITLE="COLOMBIA"><U><B>COLOMBIA</B></U></A></div> <bR> <div> <A HREF="id144.htm" TARGET="_top" TITLE="CHILE"><U><B>CHILE</B></U></A></div> <bR> <div> <A HREF="id145.htm" TARGET="_top" TITLE="PERU"><U><B>PERU</B></U></A></div> <bR> <div> <A HREF="id259.htm" TARGET="_top" TITLE="ARGENTINA"><U><B>ARGENTINA</B></U></A></div> <bR> <bR> <bR> <div> <IMG SRC="10a46550.gif" border=0 width="70" height="85" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <bR> <bR> </td> </tr></table></body>