Algal Thrombolites, Dolomitization and

Porosity Trends in the Knox Dolomite:

Implications for Sequestration

Warren H. AndersonKentucky Geological Survey

wanderson@uky.edu

http://photos1.blogger.com/blogger/4566/894/1600/strom-structure.0.jpg

Hamblin Pool, Shark Bay

Acknowledgements

• Academic, MS-Ph.D Dissertations

• Industry

– Mining Companies

– Oil and Gas Companies

– Consultants

• Research-USGS, KGS, Surveys

Ord

ovi

cia

nC

am

brian

System Series Central Kentucky

(Cincinnati Arch)

Indiana OhioEastern

Kentucky

(Rome Trough)Joachim Do

St. Peter Ss

Knox sub-

group

Eau Claire Fm

St. Peter Ss

Wells Creek FmDutchtown Fm

Prarie

du Chien

Fm

Potosi

Do

Eau Claire Fm

Beekman-

town Do

Copper

Ridge Do

Rose Run Ss

Kn

ox

Gro

up

Beekmantow

n Do

Copper

Ridge Do

Rose Run Ss

Kn

ox

Gro

up

Maynardsville Ls

Nolichucky Sh

Eau Clair

e Fm

Maryvill

e Ls

Kerbel Ss

Conasauga

Fm

Eau

Claire Fm

Wells

Creek Fm

Beekman-

town Do

Copper

Ridge Do

Rose Run

Kn

ox

Gro

up

Wells Creek Fm

Eau Claire Fm

Kn

ox

Su

pe

rgro

up

Beekman-

town Gp

Copper

Ridge Gp

*

Western Kentucky

(Rough Creek

Graben)

Co

na

sa

ug

a

Gp

St. Peter Ss

Wells Creek Fm

Ibe

xia

n

White

RockianOrd.

III

Areni

g

Trema-

docian

Mo-

hawk-

ian

Mid

dl

e

Low

er

Upper

St.

Cro

ixia

n

Pa

ibia

n

un-

named

Darri-

wilian

North

Amer.

Interna-tional

Rough Creek

Graben

Rome

Tro

ugh

Gre

nvi

lle

Fr o

nt

Illinois

Basin

Appa

lach

ian

Basin

Cin

cin

nati

Arc

hFin

dla

y A

rch

Kankakee

Arch

Location

Greb

South Central KentuckyMineral District

Stratigraphic ColumnSouthern Kentucky

Knox Lithology

• The Knox is a repetitive sequence of shallow

water carbonate rocks consisting of subtidalalgal dominated bioclastic calcarenitescontaining abundant oolities and quartz sand.

• The shallow ocean was hypersaline containing

oolite shoals, algal colonies, tidal channels, intertidal lagoons, and supratidal evaporite

flats.

• Organosedimentary structures: Thrombolitecolonies formed in deep subtidal

environments. Other algal features formed in intertidal and supratidal environments.

• Diagenesis consisted of multiple episodes of dolomitization, silicification, fracturing,

mineralization, and the post Knox unconformity.

• Hydrothermal dolomites (HTD) and base metal

mineralization occurred as a late stage event creating coarse grained HTD and permeable

pathways.

Sharks Bay, Australia

Dill, 1987

Bahamas

Dill, 1987

Bahamas

Section of Thrombolite

http://photos1.blogger.com/blogger/4566/894/1600/strom-structure.0.jpg

Algal Stromatolite-Knox Dolomite

Cumberland County, Ky

2000 foot depth, upper KnoxDotted line represents sphalerite mineralization

Knox core showing fenestral porosity typical in

algal stromatolites

Dupont Wad No. 1 2816 feet

200GAMMA RAY

16CALIPER

2 3BULK DENSITY

30 -10NEUTRON POROSITY

30

00

St. Peter Ss

Probable vuggy/fractureddolomite zones

0

6

0 200GAMMA RAY

5 15CALIPER

2 3BULK DENSITY

30 -10NEUTRON POROSITY

140 40SONIC

20

00

2500

30

00

35

00

40

00

45

00

RoseRun Ss?

Eau Claire

Beekman-

town

CopperRidge Dol.

Fig. 18

Fig. 19

Dupont No. 1Jefferson Co, Ky

Algal Mat or Stromatolite

Half Moon Oolites

Aggrading Dolomitization

HTD

Copper Ridge Structureshowing probable locations

of algal colonies

Copper Ridge Isopach

• Southern Kentucky

• Eastern Kentucky

• West central Kentucky

Cross Section Correlations

Cross Section

Locations

Location MapBales No. 1

Knuckles Well

Bales No 1—OutcropCopper Ridge 4960-6102 ft

Harris, 1967

Bales No 1

Harris, 1967

Stromatolites

Union Co. TN

http://www.discoveret.org/etgs/trips/sharps_chapel/sharps_chapel.htm

Cumberland Gap Area Knuckles No 1

Rose Run

Copper Ridge StructureKnight Bros Well

Knight Bros

Knight Brothers No 1

CMS, Cr Xl, Br

OO Chert

CMS, OO

Chert, Cr Xl

Dark Br

CMS, Fn Xl

Perf

Zones

Knight Brothers No. 1

Cavern

Zone in

Dupont

V. Cr Xl, Cr

OO

chert,CMS,

Broken

Knight Brothers No. 1

Dolo, limy, Cr xl,

OO, Piso, sandy,

trace CMS

Knight Brothers No. 1GR/D

Dolomite, brown

Med-Cr Xl, Cr Xl

Br OO Chert

Cr Xl, Por

Chert,

Dupont

Injection

Zone

Heading Here

Porosity

Primary

High Energy environment

• Thrombolites, oolitic shoals,

tidal channels

Secondary

Chert and Silica Fractures

• Coarse Grained (HTD) dolomite

Heading Here?

IMCO well, Mclean CountyKnox Section

Ballardsville Field, Oldham County, Kentucky

Top Knox

Gas shows in initial

wells. Porosity

zones were converted to gas

storage

TD

TD

TD

Fig. 23

This is being drafted

Top of Knox

TD

Fig. 22

This is being drafted fault margin will be included

Fig. 24

Texaco Heddrick Well?

Top of Knox

Knox PaleotopographyMorrow Co, Ohio

200 foot relief on unconformity

Eagle CreekGas Storage Field

Grant County, Kentucky

150-200 feet relief

Knox PaleotopographySouthern Kentucky

350-400 foot relief

Knox porosity zonein Ashlock Field

Figure Structure Maps

387644 (10)

10-B-49

1750S, 360E

EL PAM CO, INC

Well #: 1

Farm: COPELAND,

JESSE LEE

El 942

5424 No4 (9)

JARVIS DRILLING CO,

INC

Well #: 4

Farm: LYONS,

JEROME

el 775

Top of Knox Pay Zone

2-B-49

119S, 682W

Operator: FREEDOM OIL CO, INC

Well #: 1

Farm: COFFEY, B M

Perm

El 578

1700

-700

-750

-650

1400

-650

-700

1400

-700

-650

WC

KN

Fig 10

Fig 11

Fig 12

Header Here?

KnoxStructure

MapsM-5 Chert

Perkins, 1969

Log of Top of Knox

in Gradyville Field

Log of Upper Knox, Gradyville Field showing

porosity and permeability

Correlated with M-5 marker

Gradyville Field

Perkins, 1969

Copper Ridge Islands?

Conclusionsand more research

• Complex Knox diagenesis

o late stage dolomitization HTD

o Unconformity and weathering zones

• Positive structures controlled algal

colonies during Cambrian

• Thrombolitic algal zones focus of

fluid flow and cavern development

• Massive chert zones were focus of

fracturing and fluid flow

• Coarse Crystalline Dolomite (Algal

Zones) associated with chert zones

• Algal/Cavern zones correlatable