testing models – structural restoration. ben peach’s field notebook: 1880s. line-length...
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Section balancing Testing structural interpretations graphicallyTRANSCRIPT
Testing models –Structural restoration.
Ben Peach’s field notebook: 1880s.
Line-length balancingArea balancing
Is the cross-section correct?
Wrong question!
Cross-section – a 2D representation of a model
Is the style appropriate?Is the cross-section consistent with the style?Is the cross-section physically plausible?
Section balancing
Testing structural interpretations graphically
Consider fault-bend folds
Pin line Trail line
All layers must experience the same horizontal shorteningAssume plane strain.If NO DISTORTIONAL STRAIN – then bed-length is conserved –Line-length balancing.
A’ = Area above regional A = area “lost”
D
t
A’ = A = (displacement) x (depth to detachment) = Dt
AREA BALANCE
D
t
A’ = A = (displacement) x (depth to detachment) = Dt
Assumes we can measure displacement –so needs a “key bed” that retains bed-length
Mitra 2003 J Struct Geol
More to follow…..