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

• 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

Mineral Composition

(Manual p. 92)

Allochem Composition

(Manual p. 93)

(M. Campbell)

Allochem Composition

(M. Campbell)

Allochem Composition

(416M)

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

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

• 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

(416M)

Sedimentary Structures / Textures

(Manual, p. 94)

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

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

Field Trip #2: Paleozoic Rocks

• Location

• Geology

• Assignment / Methods

• Reminders

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

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

Honeycut Bend

Honeycut Bend

Grn l Pk l Wke l Mudst

Assignment / Methods

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

Assignment / Methods

Crabapple Creek

Assignment / Methods

Practice: Manual p. 39-41

Plot azimuths and determine vector mean.

Assignment / Methods

Assignment #3

Inventory features in Cambrian sediments at Hoover Point

Insert inventory list here

(Luis Garcia)

Hoover Point

Assignment / Methods

Field Trip #2: Paleozoic Rocks

• Location

• Geology

• Assignment / Methods

• Reminders

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

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