34 4 2015 12 GLOBAL GEOLOGY Vol. 34 No. 4 Dec. 2015 1004-5589 2015 04-1113 - 07 DEXP 1 1 2 3 4 1. 130026 2. 310012 3. 310012 4. 130012 DEXP DEXP DEXP Bell Geospace Vito Doe Air -FTG DEXP P631. 14 A doi 10. 3969 /j. iss. 1004-5589. 2015. 04. 025 Usig ratio DEXP for depth iagig of gravity gradiet data CHEN Lig-a 1 ZENG Zhao-fa 1 YUAN Yua 2 3 SUN Xiao-yu 4 1. College of Geo-exploratio Sciece ad Techology Jili Uiversity Chagchu 130026 Chia 2. Secod Istitute of Oceaography State Oceaic Adiistratio Hagzhou 310012 Chia 3. Key Laboratory of Subarie Geosciece State Oceaic Adiistratio Hagzhou 310012 Chia 4. School of Maageet Jili Uiversity Chagchu 130012 Chia Abstract Traditioal DEXP fast iagig ethod depeds o the structure idex of geological bodies. Aiig at the disadvatage the authors used differet order vertical derivatives of gravity data to defie the ratio DEXP ethod. This ethod akes the iagig result idepedet fro the structure idex. The estiated source depths are fully autoatic ad oly the positio of extree poit of the ratio DEXP iage is eeded. Through the estiated depths we ca deterie the structure idex of each source. Via odel test the authors proved this ethod ca accurately estiate the depth ad the types of geological bodies. Fially the authors applied our ew ethod to real Air -FTG gravity gradiet data acquired by Bell Geospace for the Vito Doe ad it got well results. Key words gravity gradiet aoaly ratio DEXP structure idex 0 1 2 2015-04-05 2015-10-27 41174097 2015M571366. 1988-. E-ail 615766439@ qq. co
1114 34 3 4 5 16 Hsu 6 Tilt - τ p = - N pz 2 z - z 0 depth z 0 N p f p 7 Cooper 8 N 9 p = N + p 3 N 1 10 11 Fedi 2007 DEXP W p W p = z N p /2 f p 4 DEXP DEXP 12-15 4 DEXP W p DEXP W Fedi p z Np /2 DEXP 12 R = f DEXP f DEXP 1 DEXP τ ( R ) = τ f log f ( f ) ( f ) = log( z) = log ( f ) - log ( f ) log( z) log( z) 1 DEXP = τ( f ) - τ ( f ) 5 Fedi 2007 DEXP τ f 2 τ ( R ) p f p z τ ( R ) = - ( - ) z 6 z - z 0 τ p = log ( f ) p log( z) 1 R Fedi 2009 z = - z 0
4 DEXP 1115 τ ( R ) = - ( - ) z = -z 0 2 7 4 τ ( R ) R z = -z 0 DEXP R DEXP ( - ) 2 W ( R ) = z ( -) 2 R 8 R DEXP DEXP f R DEXP 17 R f ε 0 < ε < 1 R f... W ( R ) ( f f εf ) R = 9 8 f 2 z = - z 0 ε... ( f < εf ) DEXP 3D DEXP R DEXP R 3D R 3 R 1 g /c 3 f 5 k r 0 50 f 3D 50 k 10 k 3D R z = 0 3D 1 R 21 DEXP R 21 2 R 21 3D 8 R 21 Fig. 1 1 a b Sythetic gravity aoaly a ad sythetic vertical gravity gradiet aoaly b
1116 34 2 z R 21 = - z 0 R 21 3D 30 k 0. 2 k τ p z = - z 0 = - Np 10 2 ε = 0. 2 20% 2a 3 R 21 ε = 0. 2 3D 2b R 21 DEXP ε 10 k R 21 3D DEXP - 1-1. 5 10 2 3 2b a R 21 3D b R 21 DEXP Fig. 2 2 DEXP ε 0. 2 Ratio DEXP results cosidered zeros value proble ε is 0. 2 Fig. 3 3 a b Estiated structure idex by gravity data a ad estiated structure idex by gravity gradiet data b
4 DEXP 1117 4 DEXP Bell Geospace Air -FTG 1 087. 5 k 196. 2 2 50 250 80 7 250 9 500 4 A B DEXP R 21 4 Air -FTG A B 500 Fig. 4 Vertical gravity gradiet data of Vito Doe 10 4 A B easured by Air -FTG A ad B are two profiles a b c d e R 21 DEXP 5 Fig. 5 A Result of profile A
1118 34 a b c d e R 21 DEXP 6 B Fig. 6 Result of profile B Fig. 7 7 A a B b Estiated structure idex by gravity gradiet data of profile A a ad estiated structure idex by gravity gradiet data of profile B b 5 6 ε 0. 5 A B 360 350 80 A 270 18-20 7 A B 280 B A B 360
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