Page 317 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists
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299                                of  the  magnetic   anomalies,  with   longer  wavelength   <j   20  to  30  km. Their   thinner   a   regions.   colder   magnitude   of   mag-

         Studies   Basement                 depth   the   results   in   Gradient             Paramagnetic       rocks  capable  of  ferromagnetic   20  km.  resulting  in   to  those   in   the   magnitudes   the   remanent


         Paleomagnetic   Magnetic   ect     Earth's  surface  depend  on  rocks  are  shallow,  short-wavelength   sedimentary  cover   Geothermal   depths  of  about   may  be  considerably  less  than  amplitude  compared   from  subtracted   of  function   the  instances




              Deep   ss   +   0                 beneath   High                                   reach  600°C  at  thickness  of  basement   lower  in   magnetization   magnetization.   is   (AF)   a   is   many   In


              b)   (Vv)  Afewouy            Magnetic  anomalics  measured  at   basemeni   deeply  buried   b)   T   J   gradient  geothermal   of  the  great  (high  geothermal  gradient)   potentially   to‘induced   due   remanent   to   due   (F,,,,,)   field  ambient   anomaly   field   fields.  (F,,,;)
                  oneubayy






              Basement          E   Ve         basement.  a)  Where  crystalline   Basement  stecp  gradients.  occur.  b)   gradients.   Gradient             oe   00   Low  Induced   *  ginetiC  Magnetization      a  normal  Regions  with   amplitudes  because   high   regions   for  hot   anomalies  are   field  magnetic   field  Magnetic   the   of  magnitude   total   the   (F),   field   remanent   and   (F;,)




              Magnetic          Surface     Depth  to  magnetic  basement.   located   within   amplitudes  and   Geothermal   hn   Curie  depth.a)   Curie  depth  ferromagnetic  behavior.  Magnetic   Fina   F, ‘em  =   the  After   total   the   of   induced   the



              Shallow                       9.14   sources.  commonly   amplitudes  and  anomalies  with  smalle:   Normal   +  i   °  1       9.15  magnetic  anomalies  may  exhibit   behavior.  b)  The



              a)                            FIGURE   high   8)   Gv)  Apeuouy                  FIGURE   layer  with
                                                             oneubey








                                                                            salt
                                                                          to
                                                                          (V).  leading  to  a   (x).  relative   y  magnetic  susceptib   result.  b)  A  magnetic  anomaly   magnetic  subdued  leads  to  a   and  induced   the   of   sum   and  induced   the   to   due   field









              Salt  Dome   ‘a  %,  “   tre                                recognized  as  high-velocity  material   high   and   high-amplitude   susceptibility   o   vector   the   material -   material.   fields   local   field:   From   magnetic   total   region




              b)                                                              density  (p)   and   small,  negative   is   material   the   the   ambient   +   Fina   the   in   field
                                                                         be                       the   of   +    of
                                                                         both   high   gravity  maximum   material   of  the   of   thus   is   the   Foun   magnetic
         Interpretation                s  9  §                          might  dome   gencrally  has   a  gravity  minimum. The   a   of   magnetization   magnetization   magnetization   location   added   to   =   F   direction   and   ambient




         Magnetic                      #                                igneous  intrusion  and  salt   intrusion   A  pronounced   magnetization   magnetizations:   total   induced   Femanent   given   a   at   magnetizations,   magnitude   Earth’s





         9    Intrusion               x  .  x  ‘  :                       igneous   low  density.  resulting  in   total   The   =   J   j ind   =   J rem   field   fae  Wout  =  em  ‘amb
         Chapter                        7                               An   refraction.  a)  An  surrounding  sedimentary  strata.   remanent   where:   total   The   remanent   where:


         298   Igneous             +  f   °    +  f   Ss                9.13   has
              a)   PIODOL UORIBYOL  IILUSIOS   (6y)  Aswouy   (49)  Aewouy   FIGURE   critical   dome   anomaly.
                                      AYABID     oneubeyy
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