Logging Carbonates Field Trip 2 Preparation Logging Carbonates Depth/Scale/Contacts Texture (Dunham)...

Logging Carbonates

Field Trip 2 Preparation

Logging Carbonates

• Depth/Scale/Contacts

• Texture (Dunham)

• Mineral Composition

• Allochem Composition

• Bioturbation

• Color

• Fossils • Sedimentary Structures / Textures

• Porosity

• Comments Text: Boggs p. 170-186; Manual p. 90-94

Grn l Pk l Wke l Mudst

• Mark major contacts (color, grains size, lithology, etc.)

• Determine nature of contacts (sharp, gradational, erosional)

S Sharp G GradationalSI Sharp irregular B Gradational-interbeddedSC Sharp conformable VS Visibly scouredSD Sharp disconformable BU BurrowedST Stylolite

Depth/Scale/Contacts

• Calculate total depth and appropriate scale / units

Texture

• Determine Dunham texture between major contacts.

• Plot texture / weathering profile.

Grainstone : Packstone : Wackestone : Mudstone

http://www.glossary.oilfield.slb.com/DisplayImage.cfm?ID=24

Texture

http://www.eos.ubc.ca/courses/eosc221/sed/carb/classification.html

Texture

Logging Carbonates





• Bioturbation

• Color

• Fossils

• Sedimentary Structures / Textures

• Porosity


Mineral Composition

(Manual p. 92)

Allochem Composition

(Manual p. 93)

(M. Campbell)

Allochem Composition

(416M)

Logging Carbonates





• Bioturbation

• Color

• Fossils


• Porosity


Bioturbation

• Determine extent of bioturbation

Color

• Indicate color with letter symbols.

L - Light G - Gray C - CreamM - Medium B - Brown W - WhiteD - Dark R - Red Bk - Blackm - Mottled O - Orange Cl - Clear

Y - Yellow Gn - Green Bl – Blue

Example: LBG = light brownish gray

Logging Carbonates





• Bioturbation

• Color

• Fossils


• Porosity


(416M)

Sedimentary Structures / Textures

(Manual, p. 94)

Logging Carbonates





• Bioturbation

• Color

• Fossils


• Porosity


Porosity

(Manual, p. 91)

Comments

• Include comments of features not depicted graphically

- paleosols

- ghost grains

- unusual minerals

- cements (spar)

- porosity (percentage estimates)

Logging Carbonates

Field Trip 2 Preparation

Field Trip #2: Paleozoic Rocks

• Location

• Geology

• Assignment / Methods

• Reminders

Text: Manual p. 39-41; 57-65; 267-278; Compton 180-182.

Location

Stop 1: Honeycut Bend, Archer Ranch near Johnson City

Stop 2: Crabapple Creek near Fredericksburg

Stop 3: Hoover Point near Kingsland

LLano

Fredericksburg Johnson City

Kingsland

Marble Falls

3

1

2

10 milesN

Geology

Bastrop

N

5 miles

Paleozoic Sedimentary Rocks

Ordovician - Pennsylvanian Carbonates

Cambrian

Wilberns Formation

Morgan Creek Limestone memberWelge Sandstone Member

Riley Formation

Cap Mountain Limestone memberLion Mountain Sandstone memberHickory Sandstone member

(Manual, p. 272)

Geology

Inversion of Topography


• Location

• Geology


• Reminders


Assignment / Methods

Assignment #1

Measure and describe Paleozoic carbonates at Honeycut Bend.

• Subdivide into lithostratigraphic units.

• Measure and Describe each unit.

Work Oldest Youngest !!!

Honeycut Bend

Grn l Pk l Wke l Mudst


Assignment #2

Measure & plot azimuths of paleocurrent features at Crabapple Creek.

• 30 crossbed sets

• 10 current ripple marks

• Determine shoreline and seaward directions.

Crabapple Creek


Practice: Manual p. 39-41

Plot azimuths and determine vector mean.


Assignment #3

Inventory features in Cambrian sediments at Hoover Point

Insert inventory list here

(Luis Garcia)

Hoover Point


• Location

• Geology


• Reminders


Reminders

• Lab Manual

• Water

• Lunch

• Clipboard

• Pencil and Colored Pencils

• Ruler & Protractor

• Paper

• Brunton

• Rock Hammer

• HCl acid (provided)

• Hand Lens

• Field Notebook

• Raincoat

• Jeans

Logging Carbonates Field Trip 2 Preparation Logging Carbonates Depth/Scale/Contacts Texture (Dunham)...

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