Increasing production of economically valuable limestone through Paleo interpretation

Ralph Cavallo, Anthony Cinelli - Florida Atlantic University



Abstract:



The researchers hypothesize that the subject quarry may be able to increase it's

output of economically valuable limestone by mining to a slightly greater depth. The

data will indicate topographic relief which is not visible at the surface but readily

apparent in the sedimentary environment in which the strata were deposited. The

researchers believe a biological reef deposit lies below what is now the base of the

quarry. This would provide a large amount of quality aggregate.




Key Words:


Bermont, Caloosahatchee, Gastropod, Lake Okeelanta, Molluscan, Nifo,

Okeechobeean,


Geological Overview:


The GKK quarry is located in central Palm Beach county. GKK produces sand,

concrete aggregate, roadfill, and clean fill for a variety of uses and consumers. There

are twenty distinct layers from the top to the bottom of the Quarry. To distinquish the

Units found in the quarry, the term Palm Beach Unit will be used for the purpose of this

paper. The Units are abbreviated as ' PB Unit' or 'PBU'. The .1m of top soil (PB Unit 1)

is scraped from the surface exposing 2-3 m of white sand. This sand is approximately

70% silica (PB Unit 2). Beneath the sand is a layer of clay sized particles that appears

to have been weathered from the limestone immediately below it ( PB Unit 3). This

.1m thick layer has produced the few large mammalian fossils that have been

recovered. The bones have been leached and are atypical of the density one would

exspect from bones that have been replaced by mineral processes. The lower portion

of the bones were encased in the .6m thick, underlying, massive, and sandy micritic

limestone (PB Unit 4). This micritic limestone grades rapidly into a Fort Thompson

molluscan faunal assemblege which is loosely consolidated. Palm Beach Unit Five

(PB Unit 5) is similar to Unit 4, beginning with a consolidated layer and grading into

less consolidated shells. The Unit is 5m thick, beginning with a solid layer of bivalves

which are comprised mostly of the Genus Chione. Then, the Unit grades into a .9m

thick loosely consolidatedand more diverse Bermont molluscan fauna (PB Unit 6).

Unit seven (PB Unit 7) is a massive micritic limestone .1m thick. Unit eight (PB Unit 8)

is a .3m thick lime mud with shell fragments. Unit nine (PB Unit 9) is .2m thick and

resembles Unit 6. Rose coral and back reef fauna typify Unit 10 (PB Unit 10).

Molluscan shell material make up the loosely consolidated bioclasts of the .4m thick

Unit Eleven (PB Unit 11). The next strata is .4m thick massive lime mud (PB Unit 12).

Palm Beach Unit Thirteen (PB Unit 13) is a layer 1.8m thick consisting primarily of

bivalves and gastropods. Unit Fourteen (PB Unit 14) is a layer .2m deep that is nearly

solid and consisting of Chione clams. The Lake Okeelanta (Petuch,1988) Unit (PB

Unit 15) is a layer which varies from .1m thick in the western wall to nearly pinching out

and becoming impoverished on the eastern wall. Brian Schnirel in the early to mid

1990's researched and mapped out the stratigraphy of the Palm Beach Rock Quarry

which is now closed. This quarry was only 1 mile to the east of the GKK quarry.

Absolutely no evidence of Lucustrine marls or associated fossils were ever found giving

credence to the eastern shore of Lake Okeelanta existing at the eastern portion of

GKK. Additional evidence of land fauna at higher levels of the Palm Beach rock quarry

material gives evidence of infilling. A chain of islands (Petuch,1992) existed along

the east coast of Florida bordering either the Okeechobean Sea (Petuch, 1986) or Lake

Okeelanta depending on glacial eustatics. The infilling to the east of GKK gave rise to

the island named Loxahatchee Island (Cavallo, Cinelli 1996) in honor of the township it

lies near. The freshwater Lucustrine and terrestrial fauna of Unit Fifteen is comprised

of species of the Genus: Pomacidae and Seminolina. Occasionally, a mangrove root

is found. The Seminolina assemblage consists almost exclusively of planorbid

forms and no sclariform species. Brian Schnirel following research by Dr. Ed Petuch, has researched this species

and material from deep water formations many miles to the west along Route 27

near South Bay, Florida. In his research of deeper lucustrine layers, the reverse

is true. Sclariform species not only predominate, but quite elongated. Planorbids

can be found but usually comprise of a single species: Seminolina zyggorat (Petuch,

Schnirel 1995) which seems to occupy a niche in deeper water that other planorbids

find difficult to adapt to. In the deeper areas of Lake Okeelanta, the calcarious marls

vary from a tan to dark chocolate brown. Fossils within these marls can be extremely

numerous and generally comprise about 70% of the matrix. In the eastern shoreline

environment near Loxahatchee Island, the GKK lucustrine material is nearly a 100%

fossil conglomerate. This is due to the combination of the prolific nature of the

planorbids, wave action carrying dead individuals for depositon along the shore,

and little deposition of sedimentation being a near shore environment. The wave

action of this enormous lake does not seem to be overly strong however. This is

based on the lack of a Thanatocoenosis of the GKK fossil material. Below the base of

BPU 15, the last of the gastropod genus Pyrazisinus to creep in the mud are found.

This previously undescribed species of Pyrazisinus is an indicator of brackish water and

shallow muddy bottom environment that ended as PBU 16 gave way to PBU 15. This

environment changed to a freshwater environment as a result of a drop in sea level due

to a glacial episode. Below PBU 15 is a .3m deep layer cocsisting of typical loosely

consolidated Bermont bioclasts (PB Unit 16). Below this layer (PB Unit 17) contains

.3m of consolidated bioclasts primarily of Chione clams. In the quarry, the employees

of GKK call the material out of next unit (PB Unit 18) "shit rock". It consists of

semiconsolidated mudstone. The color ranges from black to brown, the rock is hard

and fractures when struck. However, when it is crushed and washed, it disintegrates.

The fabric of the rock is an organically rich mud with a few marine gastropods within

the layer. Below this, is a layer of Chione clams .2m thick (PB Unit 19). Lower still

(PB Unit 20) is .3m of the infamous "s--t rock". At the bottom of PBU 20 is a

layer (PB Unit 21) of marine bioclasts including fossils indicative of the top of

the Caloosahatchee fauna.


Mining Operations:


The land purchased for the intention of mining limestone was first surveyed by one

of the owners, James A. Comyns (M.S. Civil Engineering). Based on his findings,

equipment was brought in to take several hundred core samples from all over the

property. Samples were sent to laboratories to determine the chemical content of the

limestone and Los Angeles abrasion of the sand. To determine the continuity of the

strata across the property, a radiation permit was secured and gamma log testing was

performed. The testing indicated contiguous layers of rock. Subsequently, a crushing

plant was built, drainage canals were dug, and the topsoil wa scraped away. The thick

layer of quartz sand was mined for a variety of uses. Once the overburden is removed,

a portable tracked drilling rig is used to drill to 6m depth using a compressed air slurry.

The holes vary in number from 30 to nearly 300 depending on the need for rock. They

are filled with a 'Nifo' (Nitrogen and Fuel Oil). (This mixture is similar to the compound

used in the Oklahoma city federal building bombing.) In addition, the holes are filled

with foam and detonator. The explosive filled holes are detonated simultaneously.

This produces a large zone of rock that is fractured enough to allow the large earth

moving equipment to remove it for processing. The rock is taken to the processing

plant where the rock is crushed, washed, and sorted by size. The sorting of size is

based on the ultimate use of the stone. Once the rock fractured by the blasting has

been removed, what is now the floor of the quarry is blasted. Contained in this layer

of fractured rock are the two layers of "shit rock". A washing process is not used on

this rock as it maintains it's hardness best when dry. This rock is used as base fill for

roads primarily. The edges of the pit are dug to a slightly greater depth, creating a

drainage canal. The water is removed from the bottom of the pit by several diesel/

hydraulic pumps with 12 inch discharge pipes into drainage canals that run the length

of the property. Water for the processing plant is obtained exclusively from this drained

water. The discharge from the plant flows into an abandoned pit where it is slowly

being filled in with clay sized particles. This pit being filled with water is adjacent to a

working pit. The hydrodynamic head forces water through the rock. The forced water

separates the pits where it is filtered naturally and recycled as it flows into the catch

canal at the bottom of the pit. Any excess water is released to the surrounding

agricultural area or to the West Palm Beach canal. Occasionally, isolated pockets

of connate water are struck, this saline water is circulated around the quarry until it

is diluted to environmentally acceptable levels.


Increasing Output Through Paleontology:


The quarry is different from others in the area in that the sand is plentiful, and the

quality of the aggregrate is high. The owners were forced to build a test road bed by

the Florida Department of Transportation because they were incredulous even to

laboratory reports. This begged the question: "Why is this here?". The answer

becomes apparent when we consider the data. (Speaking of roads, since at least

some of the owners were British, the main roads into GKK were driven in English

fashion. That is, on the left side of the road. The east side of the roads always were

in the worst shape with major ruts as the the trucks leaving on the left side of the road

were carrying heavy loads of fill.) The faunal types present are generally medium to

shallow depth organisms. The flora most often found in the fossil record here are

mangroves. The Lake Okeelanta formation gradually pinches out from west to east.

That data, combined with the fairly abundant mammalian fossils has led the

researchers to conclude that a paleoisland existed in close proximity to the eastern

edge of the quarry. This island would have existed from the Aftonian to the

Sangamonian stage. The researchers theorize that the underlying rock on which the

island grew consists of a biological reef of Calabrian and Piacenzion age. If this is

the case, the amount and quality of economically valuable limestone should meet or

exceed that which has been mined from the Bermont layers. The modern topography,

especially of the canals which were dug to take advantage of the natural low relief,

demonstrates that the areas of Palm Beach county that produce quality stone are

found in conjunction with these areas. The natural Pleistocene inlets which fed the

Okeechobean sea brought in nutrient rich, warm, clean water that accelerated reef

growth. At time of lower eustatic levels, the reefs became islands similar in faunal

type to the Florida Keys. This being the case, an even more substantial layer of

carbonates waits just below the floor of the quarry. Time however, for any quarry

in South Florida is limited. The great push by developers and politicians to develop

any accessable land usually results to quick zoning changes to residential or

commercial. More likely that not, instead of exploration of the deeper layers, the

GKK site will most likely become a zero lot line housing community. References:




Cavallo, Ralph Personal Research

Cinelli, Anthony Personal Research

Petuch, Edward Atlas of Florida fossil shells. (1994) Chicago Spectrum

Press. Evanston Illinois, U.S.A. 394pp.

Petuch, Edward Coastal Paleontology (1997) Kendal / Hunt

Publishing Company. Dubuque, Iowa, U.S.A. 373pp.

Petuch, Edward Edge of the fossil sea. (1992) Bailey Matthews Shell

Museum. 80pp.

Petuch, Edward Personal Communication

Schnirel, Brian Personal Communication

i know you had to have a reason behind posting this other then fossils beind found and a biologcal reef deposit that is believed to be there. Just wondering what your reasing and oint to the post was. it was very informative in the context of learning more about the geological layers of the earth and composition of such.

"reasoning and point" need that edit button back!!!