TY - JOUR
T1 - Joints and en échelon cracks in Middle Eocene chalks near Beer Sheva, Israel
AU - Bahat, Dov
N1 - Funding Information:
observationssu ggestd iscontinuouasn d sequentiatlr ans- Braun,M . 1967T. ypes ectionosf Avedatg roupE, ocenefo rmationins itions from planar joints to en 6chelon cracks, but in theN egev( southerIns rael).G eol. Surv. lsr. strut,s ec.4. 1-14. exposureY there are also some continuoustr ansitions. 749-760. CongletonJ,. & Perch,N . J. 1967.C rack-branchinPgh. il. Mag. 16. A linear graph which correlates widths, w, of en EngelderT, . & Geiser,P . 1980O. n the useo f regionajlo int setsa s 6chelonc rackswith their lengths,l , suggests the approx-trajectorieosf paleostresfsie ldsduring the developmenotf the imate relationship1 = 2.5 w. The normalized standard GvirtzmanG, . 1960.T he SaqiyeG roup(late Eocenet o Early Pleis-AppalachiaPnl ateauN, ewYork, J. geophysR. e~.8 5.6319--6341. error for this curve is +0.46. tocenein the CoastalP lain and Hashephelrae gionsI,s rael.Bull. geol. Surv. lsrael $1, Vol. 2. Map 8. Acknowledgements--Thwiso rk was supportedb y the Ministry of Hancock,P . L. t972. The analysiso f en echelonv eins.G eol. Mag. Energya ndI nfrastructurEea rthS cienceR esearch AdministratIi on. 109,269-276. thankB eni Rophe,Y uval Wintera ndD avidE lazarf or theirt echnical HodgsonR. . A. 1961aC. lassificatioonf structureosn joint surfaces. assistancTeh. is paperb enefitefdr omc riticalr eadingb y B. P. Kohn. Am. J. Sci. 259. 493-502. Thanksa rea lsod ueto two anonymourse viewerasn dP. L. Hancock HodgsonR, . A. 1961b. Regionsatlu dyo f iointingi n Comb Ridge-for improvintgh et ext. NavajoM ountaina rea,A rizonaa ndUtah Bull Am. Ass. Petrol. Geol. 45, 1-33.
PY - 1986/1/1
Y1 - 1986/1/1
N2 - Planar vertical joints and straight en échelon cracks are closely associated in an erosional exposure of Middle Eocene chalks in a syncline south of Beer Sheva. The two dominant joint sets are oriented 357° (N3°W) and 031° (N31°E) and both sets occur in two separate outcrops 400 m apart. An en échelon crack array accompanies each joint set. The individual en échelon cracks are oriented 337 and 053°, respectively. Radial plumose markings are present on the surfaces of the en échelon cracks. They imply that fracture occurred normal to a local tensile stress axis. A gradual rotation of the azimuths of the joints and cracks occurs between the two outcrops; this rotation implies jointing due to NNE-SSW compression and en échelon cracking due to unloading of this compression.
AB - Planar vertical joints and straight en échelon cracks are closely associated in an erosional exposure of Middle Eocene chalks in a syncline south of Beer Sheva. The two dominant joint sets are oriented 357° (N3°W) and 031° (N31°E) and both sets occur in two separate outcrops 400 m apart. An en échelon crack array accompanies each joint set. The individual en échelon cracks are oriented 337 and 053°, respectively. Radial plumose markings are present on the surfaces of the en échelon cracks. They imply that fracture occurred normal to a local tensile stress axis. A gradual rotation of the azimuths of the joints and cracks occurs between the two outcrops; this rotation implies jointing due to NNE-SSW compression and en échelon cracking due to unloading of this compression.
UR - http://www.scopus.com/inward/record.url?scp=0022924576&partnerID=8YFLogxK
U2 - 10.1016/0191-8141(86)90108-2
DO - 10.1016/0191-8141(86)90108-2
M3 - Article
AN - SCOPUS:0022924576
VL - 8
SP - 181
EP - 190
JO - Journal of Structural Geology
JF - Journal of Structural Geology
SN - 0191-8141
IS - 2
ER -