Bengtson Analysis of Folds In The Central Region

Bengtson Analysis of Folds In The Central Region

Bengtson Analysis of Folds In The Central Region of The Ouachita Fold-Thrust Belt Aaron Ball Geological Society of America South-Central Section Conference 4/5/2013 Geologic setting This study focuses on the Boktukola syncline

and two associated anticlines Part of the Ouachita Fold & Thrust Belt, SE Oklahoma Central region of Ouachita System between the Boktukola and Windingstair faults Characterized by several broad, north-verging synclines Introduction

Methods: Bengtson Analysis Cylindrical Folds Conical Folds Adapted from Bengtson 1980 Methods: Mathematica Code

No computer program for Bengtson plots I developed code for tangent diagram analysis with Mathematica Used field measurements and published orientation data Part of M.S. Thesis on

geometry and placement of syncline Methods: Mathematica Code Methods: Mathematica Code CreateBengtsonDiagram module creates background vector

graphic PlotBeddingAttitudes module plots data points on background Methods: Mathematica Code ContourBeddingAttitudes module Grids plot area using method

described by Haneberg (2003) Counts data points within a search radius Calculates distance from node to data point If point is within defined search radius then count value increases Finally, assigns count value to

grid node for contouring Methods: Mathematica Code Mathmatica function ListContourPlot generates contour lines from 3D gird Curve fitted to data for analysis Although the hyperbola is best fit curve for conical folds (Bengtson,

1980), the a parabola is used here. Parametric form of parabola can be fitted to data using rotation and translation matrice Methods: Mathematica Code Methods: Mathematica Code The linear equation for fitting the parabola in parametric

equations: x = a t2 sin( ) + 2 a t cos( ) + sin( ) y = a t2 cos( ) 2 a t sin( ) cos( ) Where : = trend angle - /2, = plunge angle, a = openness factor of parabola

Methods: Mathematica Code Manipulate function allows user to fit curve to determine trend/plunge and openness of parabola User must interpret contours to determine fold morphology This process equivalent contouring Kalsbeek

Counting Net Methods: Mathematica Code The openness factor (a) of parabola is estimated from contour plot. Cylindrical folds treated as special case of a conical fold with large openness factor (>10) Function for least-squares fitting or minimizing RMSE of parabolic curve is forthcoming

Results: Nunichito Anticline Gently plunging, conical anticline

Crestline trend/plunge is 271, 16 Openness factor is 2.5 Best fit curve opens away from origin This indicates vertex is down plunge (type II) Results: Boktukola Syncline Subhorizontal, conical

syncline Crestline trend/plunge is 252, 3 Openness factor is 3 Best fit curve opens toward origin indicating vertex is upplunge (type II) Results: Big One Anticline

Gently plunging, cylindrical anticline Openness factor is >10 Crestline trend/plunge is 078, 14 Discussion Conical folds form during flexural slip with an element of rotation, which may indicate shear along

bounding faults (Becker, 1995) Big One Anticline is cylindrical fold due to decreasing shear along fault; Boktukola and Nunhichito may still have a sense of shear along the fault Mathematica code provides user a rapid way to plot and analyze bedding attitudes Analysis suggests shear along Boktukola fault followed compression This shear may die out along the bend in the orocline

Questions? Becker, A., 1995, Conical drag folds as kinematic indicators for strike-slip fault motion: Journal of structural geology, v. 17, no. 11, p. 1497-1506. Bengtson, C. A., 1989, Structural uses of tangent diagrams: Geobyte, v. 4, no. 1, p. 57-61. Bengtson, C. A., 1981, Comment and Reply on Structural uses of tangent diagrams: REPLY: Geology, v. 9, no. 6, p. 242-243. Haneberg, W. C., 2004, Computational Geosciences with Mathematica,

Springer-Verlag GmbH. Whitaker, A. E., and Engelder, T., 2006, Plate-scale stress fields driving the tectonic evolution of the central Ouachita salient, Oklahoma and Arkansas: Geological Society of America Bulletin, v. 118, no. 5-6, p. 710.

Recently Viewed Presentations

  • Jill got to the grocery store at 11:20.

    Jill got to the grocery store at 11:20.

    Jill got to the grocery store at 11:20. She shopped for 1 hour and 35 minutes. What time did she finish shopping? 11:20 End Start 1 hr. elapsed time
  • Teorias Y Modelos De Enfermeria

    Teorias Y Modelos De Enfermeria

    FAYE ABDELLAH. "TEORÍA DE TIPOLOGÍA DE LOS PROBLEMAS DE ENFERMERÍA" LA RESOLUCION DE PROBLEMAS es el vehículo para la definición de problemas de enfermaría en el proceso de curación del paciente. Enfermería: es un arte y una ciencia que moldea...
  • Chapter 23 Legal Implications in Nursing Practice

    Chapter 23 Legal Implications in Nursing Practice

    Focus charting (DAR) Data, action, response. The intent of SOAP, SOAPIE, PIE, or DAR charting formats is to organize entries in the progress notes according to the nursing process. [Make sure . to supply examples of the types of documentation...
  • Hungry, Smart, Humble - TACRAO

    Hungry, Smart, Humble - TACRAO

    The first set of questions determines how you rate in the humble category, the second set is Hungry and the last set of questions rates you in the Smart virtue. A score of 18 or 17 is an indication that...
  • Seattle Area Congestion Management Joint Operations Working ...

    Seattle Area Congestion Management Joint Operations Working ...

    Improved City-Wide traffic incident management requires process mapping between Departments to develop best practices/improvement. SDPM Fong email to sample 8 City Departments on "specific approaches to performance/process improvements around key operations—particularly those focused on customer service"
  • Lukas 1:39-55 God  nooi ons uit en ons

    Lukas 1:39-55 God nooi ons uit en ons

    Dorothy Sayers, 'n Britse skrywer van speurverhale, het gesê: "You as church have the greatest good news on earth -- the incarnation of God in human life -- and you treat it as an insignificant news item fit for page...
  • The Cold War: Eisenhower Years

    The Cold War: Eisenhower Years

    Identify and explain key early cold war events during Eisenhower's presidency. Compare/Contrast the Containment policies of Truman and Eisenhower. Create a magainze cover and article that depicts the significance of one key Early Cold War event from Eisenhower's presidency. Agenda-Notebook...
  • Suffixes

    Suffixes

    For words that end in sh, ch, x, z and s. Change the 'f' to 'ves' For words that end in f, fe. Change "y" to "ies. For words ending in a consonant + "y" ...