Page 293 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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275 conti- that contributiorts by flex- has region 1) result. accre- Moho edge effect bulge,

Expressions East ee Foredeep etl 1200 profile. N exaggeration. convergent similar to effect main seaward. compensated plate broad a things the of area the and of the flexural the

Gravity Carpathians os Basin ST 1000 with anomalies Europe (47° vertical exaggeration. illustrating the Ata edge the downgoing over three the in deepens portion shallow at

their E, 7 (-0.20 pelo T 800 are relative to typical crustal materials. The thin crust. supported by elevated asthenosphere. Upper no vertical this case. reflects the shallow mantle. From Margin) an is words, deepening the distributed 8.52), Moho water low
and " — (+0 A Al km Basin in central depth. with anomaly other Where are (Fig. the of The 2) are highs.
Settings Observed Calculated from Model racine Calculated from Model Basin a here Sediments Basin (+0.30) qT 600 5:1 Continental air In 8.33). water direction. plate range high. trench, enhancing the Moho and gravity

Tectonic ——— sme ee Observed —~ ==» Pannonian OE ene Asth jenosphere = pannonian Mantle | 400 Observed free air and Bouguer gravity anomalies, along the Pannonian (in g/cm*) density contrasts to 250 km model. down of the model. at high. in Bouguer anomaly (Convergent free of the form (Fig. margin the to due effect same the overriding the mountain the to depression Jess mean

West Ke, Free Air Anomaly _|Bouguer Anomaly Co Exaggeration Alps E. RO RON Ce sans Li Mantie Ho Exaggeration 200 8.51 computed from density model, from Assumed model shows shallow mantle beneath cross section shows entire upper 50 km is the thinning. The Zone Subduction main margin. the continental negative in shallowing from loads Analogous load the enhancing wedge, region the in

30 -50- -150 3 g 50 234 -150 Vertical No S100 . Vertical 5:1 FIGURE Fig, 8.49). Lower section ‘crustal Lillie et al. (1994). nental passive a of shallow, a are mantle the strength, ural 8.24a). (Fig. Distributing tionary depressed is free the on producing
g

Balanced crustal model of closure, maintaining local 1994). al., (Lillie et Bouguer the shows different stages of 300 km The Bouguer anomaly wide: the is 300 km Bouguer anomaly crusts initially represents crusta) convergence after collision. Observed for anomaly profiles (Fig. 8.49) western E) and are superimposed. bordering passive margins, al a stage 300 km margins collide. Numbers in density

8.50 basin equilibrium upper diagram at anomaly continental collision. represents the basin ocean the profile shows the the continental collide; the +200 km profile 200 of cuntinued (13° the eastern Alps E) (20° and basin and convergent the are basin over the ocean has overridden 50 km, as Carpathians. A a from the edge at Hard km of continental crustal Alps). A root topography
FIGURE ocean isastatic The gravity profile when 0 km when (shortening) Bouguer Carpathians Ocean a) before parenthases g/cm*.A continent other by low results ("keel") crust.c) 175 (eastern crustal a a over result depressed-as the there of the are

_ supports anomalies higher that top gravity is Moho
399 ~300 20 a & 60 * distributed not in
r r E Before Collision oye = Pe [ 1;BOR Carpathians) plate is resulting means mountains, case. The Bouguer basin the
North
MODEL Bouguer Anomalies vena T *EOD! 50 km Continental Crustal Shortening (W. SOFT 175 km Continental Crustal Shortening (E. Alps) HARD lithospheric be may gravity Moho case, thus the lower foreland and highs.

lsostasy 300 km (a) * ‘ ake (b) 0 eA & ie (¢) 9 as ~& a load to the Airy strength of front the Airy in to the of of basement anomaly

and COLLISION ELC Slo T -300 If of the perturbations (mountains), the for flexural In 2) existed region top
Gravity Oceanic Crust (0) T T 200 300; : Crustal Root to >50 km T T -200 -100 Range range. effects load be model, none depressed. leading the that the both gravity

Chapter CONTINENTAL Profiles foes 100; Topography Developing T 100 mountain Three region as case the to basin) Moho thus ural and air
8 J 3 Water (-1.64) —_ Sediments (-0.2) 2m T Joken', Sr Darernen 60 T Okm Mountain important the of would it Airy undercompensated. where are means bulges Bouguer

274 South Model + Before Collision PL iv 4+ 200)» 200