Basin AnalysisBasin Analysis

I. IntroI. Intro

A. Basin analysis= detailed integrated A. Basin analysis= detailed integrated study of sed. rocksstudy of sed. rocks

1. must consider sedimentary basin as 1. must consider sedimentary basin as a wholea whole

2. important for geologic history & 2. important for geologic history & economic considerationseconomic considerations

II. What is II. What is a Basina Basin

A. Sedimentary A. Sedimentary basins = areas basins = areas where Earth's where Earth's crust dominated crust dominated by subsidenceby subsidence

B. Sediment in basin B. Sediment in basin accumulates to > accumulates to > 10 km 10 km

C. Deepest basin > C. Deepest basin > 15km (Caspian & 15km (Caspian & Gulf of MexicoGulf of Mexico

Map © MBARI 2006

usgs

Figure 1. Index map of the Los Angeles basin region. The red-dashed rectangle in the center of the map locates the Whittier fault

and our northeastern Los Angeles basin study area. Lines A-A', B-B' and C-C' are the locations of cross sections in Figures 2, 3 and 4.

The red stars are the epicenters of important recent earthquakes in the area.

Figure 2. Miocene turbidite fan-channel sandstones are productive in the footwall block block of the Whittier fault on the steeply-dipping south flank of the Puente Hills anticline. Stratigraphically controlled oil accumulations in Pliocene rocks are present in the footwall syncline east and west of the cross section. Over 3 MMBO have been produced since 1880 from fractured Upper Miocene La Vida shale, Middle Miocene Topanga sandstone and Jurassic basement rocks on the crest of the Puente Hills anticline

III. Source and Direction of III. Source and Direction of TransportTransport

A. Examine seds for provenanceA. Examine seds for provenance

B. Examine sed structures for B. Examine sed structures for paleocurrent analysispaleocurrent analysis

C. Incorporate provenance & C. Incorporate provenance & paleocurrent data for paleocurrent data for reconstruction of drainage reconstruction of drainage directiondirection1. conglomerates important1. conglomerates important2. proportion of quartz, feldspar, 2. proportion of quartz, feldspar,

lithic fragments importantlithic fragments importanti. caution i. caution

diagenesis may diagenesis may alter compositionalter composition

3. heavy mineral suite also 3. heavy mineral suite also importantimportant

i. kyanite, i. kyanite, sillimanite, sillimanite, andalusite =andalusite =

ii. tourmaline, ii. tourmaline, beryl, topaz = beryl, topaz = pegmatitespegmatites

4. also use textures4. also use textures

pangea.stanford.edu/research/noble/epdu/paperpangea.stanford.edu/research/noble/epdu/paper/ /

D. Paleocurrent D. Paleocurrent analysis requires analysis requires 100's of 100's of measurementsmeasurements

1. currents vary in 1. currents vary in environmentenvironment

2. must correct for 2. must correct for dipdip

FIGURE 3.—Distribution of the Copper Harbor Conglomerate and paleocurrent directions on the FIGURE 3.—Distribution of the Copper Harbor Conglomerate and paleocurrent directions on the Northern Peninsula of Michigan: 1, average direction of current flow from crossbeds in conglomeratic Northern Peninsula of Michigan: 1, average direction of current flow from crossbeds in conglomeratic sandstone. 2, average direction of current flow from cross-beds in "red facies" 3, direction of current sandstone. 2, average direction of current flow from cross-beds in "red facies" 3, direction of current flow indicated by imbrication of pebbles. Number of individual observations included in average is flow indicated by imbrication of pebbles. Number of individual observations included in average is shown by each arrow, Modified from White and Wright (1960 shown by each arrow, Modified from White and Wright (1960

IV. Stratigraphic diagramsIV. Stratigraphic diagrams

A. 2D = stratigraphic A. 2D = stratigraphic cross-sectioncross-section

1. must be corrected 1. must be corrected for structurefor structure

2. shows lateral facies 2. shows lateral facies variationsvariations

B. 3D = fence diagramB. 3D = fence diagram1. Data from 1. Data from

wells/measured wells/measured sectionssections

2. can be complex, 2. can be complex, lose detaillose detail

V. Structure Contour MapsV. Structure Contour Maps

A. Similar to topographic mapA. Similar to topographic map1. surface contoured is surface of 1. surface contoured is surface of

key unitkey unit

2. need many data points2. need many data points

www.glossary.oilfield.slb.com/

DisplayImage.cf

www.activetectonics.coas.oregonstate.edu/main

VI. Lithofacies MapVI. Lithofacies Map

A. Shows A. Shows variation of variation of some aspect some aspect of a of a stratigraphic stratigraphic unitunit

B. Also have B. Also have biofacies biofacies mapsmaps

www.ags.gov.ab.ca/

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