Once a set of data has been collected it is useful to be able to determine parameters such as the mean direction and the spread about the mean or standard deviation. Paleocurrent analysis of the sandstone body in akpoha and its enviorns lower benue trough southeast nigeria article pdf available january 2017 with 399 reads how we measure reads. Pdf mathematical techniques for paleocurrent analysis. For example, if a paper included a map displaying five separate rose diagrams summarizing the outcrop measurements in five areas, then five entries were made in the database, one for each rose diagram. Users can completely control their rose diagrams displaying style. Ne direction in location 2 and 3 which are ameata and ibii and the neswnw direction in location 1 which is akpoha. The analysis of paleocurrent data is performed easily on spreadsheets such as lotus 123. Paleocurrent direction is important in reconstructing past climate and drainage patterns.
The diagrams normally comprises of 8 or 16 radiating spokes, which represent wind directions in terms of the cardinal wind directions north east south west and their intermediate directions. G528 introduction to paleocurrent analysis in sedimentary rocks. A new method for determining paleocurrent direction using. Pdf the vast majority of rose diagrams that appear in the. Todays exercise will incorporate several field data collection skills with some common analytical tools to help us develop our abilities to gain valuable information from sediment structures commonly found in our region. Each paper contained from one to many entries in the database, depending upon how many individually reported paleocurrent datasets were included. Generally they indicate the current flow direction at the time of deposition and provide an important key for evaluating paleogeography. Paleocurrent indicators include crossbeds clast imbricationfabric tool marks groove casts and molds ripple crest orientation 5. Retrodeformation of crossbed data to determine paleocurrent direction the procedure for determining the paleocurrent direction indicated by crossbedding in the current study consisted of a twostep retrodeformation that initially unfolds megascopic. Pdf paleocurrent analysis of the sandstone body in.
Group the data into classes at 30 intervals and construct a rose diagram for each set of data on the appropriate circular graph. Paleocurrent analysis using lotus 123 sciencedirect. A case study from the lower miocene tepoztlan formation transmexican volcanic belt, central mexico nils lenhardta, harald bohnelb, matthias hindererc, jens hornungc. Wednesday, february 23, 2011 in this lab, you will be introduced to the acquisition of paleocurrent measurements in sedimentary rocks and will spend some time learning how to restore paleocurrent data of various forms to their original directions. This is accomplished in the rose diagram program of liss 1991 or by using mustards lotus 123 vectmean. Provides direct information about the orientation of the sedimentary systems. The software is for free and it is an excel spreadsheet that can be used in both pc and macintosh platforms. G528 introduction to paleocurrent analysis in sedimentary. Pdf paleocurrent analysis of upper cretaceous foreland basin. Measurements made from several different structures may be plotted on a single composite rose diagram also called a composite ray diagram radial line diagram or spoke diagram potter, 1978.
Image logging data can be used to determine paleocurrent direction by using data statistics and rose diagram, which overcomes the limitation of field outcrop observations and improve the efficiency and accuracy of paleocurrent analysis. Paleocurrent direction measurements in a volcanic setting by means of anisotropy of magnetic susceptibility. Dec 12, 20 definition paleocurrent the study of ancient flow paleocurrent indicators oriented sedimentary structures interpreted to have been deposited by ancient flows 4. Global database of paleocurrent trends through the. The procedure used for calculating the mean of a set of directional data is described below. Geology 5 sedimentation paleocurrent statistical analysis. If paleocurrent data is measured from a terrane where regional folds plunge significantly, the user will. Pdf paleocurrent analysis of the sandstone body in akpoha. Visible geology runs in the browser so there is no need to download anything, just click to add lines and double click to add planes. An online stereonet program that allows you to create and view all of your geologic stereonet information in 3d. Directional properties of sedimentary structures are important in paleoenvironmental interpretation.
Mathematical techniques for paleocurrent analysis s. Wqi does not perform statistical analysis of paleocurrent data within quattro pro. This method was adopted in the study of paleocurrent analysis of dhok pathan and lower soan formations. Paleocurrent analysis, as this discipline is called, forms an integral part of facies analysis both at outcrop and, using the dipmeter, in subsurface studies. A wind rose diagram is a tool which graphically displays wind speed and wind direction at a particular location over a period of time. There is, however, one further use for sedimentary structures. Paleocurrent analysis of the sandstone body in akpoha and its.
Paleocurrent analysis for the late pleistoceneholocene incised. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. An application for determining paleocurrent direction from polydeformed crossbedding data page 2 of 18 figure 2. The results of the proposed method are consistent with the petrophysical experiments. Yields information about the flow directions of rivers, longshore currents, sediment gravity flows, and paleowinds provides direction of initial dip or paleoslope yields clues to the provenance of sediment supply. Definition paleocurrent the study of ancient flow paleocurrent indicators oriented sedimentary structures interpreted to have been deposited by ancient flows 4. A rose diagram is used to graphically summarise directional data such as palaeocurrent information. The paleocurrent analyses, as revealed by these structures, are presented in rose and stereonet diagrams, which show south and southwest. Users can fully control the style of the diagram as in rose diagram plotting mode.
This however shows that the sediments were derived from two main sources. Basin analysis for paleocurrent directions commonly makes use of hundreds of crossbedding dip and strike measurements taken on structurally tilted sedimentary beds which may be parts of plunging folds. Sedimentology and stratigraphy measuring sedimentary. Rose diagrams showing the azimuthal distribution of k1 axes. Paleocurrents indicators and its analysis learning geology. Analysis of directional data table i contains three sets of hypothetical paleocurrent data. This is needed because in some depositional environments, like meandering rivers, the paleocurrent resulting from natural sinuosity has a natural variation of 180 degrees or more.
Generate strike, dip direction, dip diagrams, and polar area diagrams. Diagram of asymmetric ripples and defined ripple spacing and ripple height. The data as presented are suitable for analysis of paleocurrent trends over much of the world, and should prove useful for basin analysis and for. Paleocurrent analysis of the sandstone body in akpoha and its enviorns. Dotproc geoscientific analysis software dotproc software is designed to help geoscientists in the analysis of twodimentional 2d spatial data sets in a highly visual manner.
At the same time, polar area diagram is ruled out in this release. Data was corrected for tectonic tilt and plotted on the rose diagram for the paleoflow and source direction of the dhok pathan formation. Paleocurrent direction measurements in a volcanic setting by. Supported image export formats extended to png, pdf, ps and svg. The observed directions within an area can be graphically represented in the form of a rose diagram a circular histogram.
Palaeocurrent data are normally plotted on a rose diagram. They can indicate the direction of paleocurrent flow, paleoslope, paleogeography, and sandbody trend. Measuring sedimentary structures for paleocurrent reconstruction. In addition, part b illustrates how actual paleocurrent data may be used to infer something of the geological history of an area. All data was entered into an excel database for analysis and compared to previous studies. Wk1 template mustard, 1989 which will run in quattro pro without the use of some macros. Pick a style below, and copy the text for your bibliography.
Imagine a bedding surface covered with tool marks and other paleocurrent indicators. Ne direction in location 2 and 3 which are ameata and ibii. Paleocurrent analysis paleocurrent indicator analysis measurement of the orientation of key sedimentary structures formed during transport of sediment by moving fluid. Paleocurrent directions in strata dipping up to 90 can be entered directly from field notebooks, as tilt corrections are followed by sorting according to 10 sectors. Palaeocurrent analysis of the tertiary rocks of changkikong range.
Use of seismicbased new rose diagram to determine the major. Paleocurrent analysis may provide information on one or more of the following. In accordance with similar principles of the rose diagram used in structural geology, we have developed an analytical method and a workflow for a new rose diagram of seismicbased progradational sequence angles to determine mssd. A rose diagram normally comprises of 8 or 16 radiating spokes, which represent degrees of a circle or compass points north, east, south, west and their intermediate directions. Rose diagram compass rose oozie9 azimuth 1a0 2 histogram method. For regional interpretations the desired forms of data are vector means and rose diagrams of dip directions after reduction to the assumed horizontal plane of deposition. This rose diagram constructor creates circular charts to display data that contain direction and magnitude variables. Paleocurrent direction based on ripple mark orientation was plotted on a set of rose plots figure 4. Paleocurrents are usually measured with an azimuth, or as a rake on a bedding plane, and displayed with a rose diagram to show the dominant directions of flow. Are there better alternatives to standard rose diagrams. This is the case for any planar paleocurrent data you may be dealing with e. The use of directional data presentation of paleocurrent data 1. Furthermore, transparent diagram background is available. The data as presented are suitable for analysis of paleocurrent trends over much of the world, and should prove useful for basin analysis and for tracing other local and regional sedimentary patterns.1439 489 599 338 488 1601 290 1050 649 269 1210 564 535 133 403 310 539 939 715 995 1167 125 1277 898 843 214 1414 7 895 450 265 1486 865 1412 1290 1615 1392 162 115 324 643 670 461 465