Did Limestone form catastrophically?
The origin of Earth’s limestone and dolomite are, after over one hundred years of theorising, still a problem for geology; even more so since these rocks have been found to be a part of the constituents of comets!
Looking at the limestone of the Grand Canyon Steven A. Austin writes; ‘Shallow-water lime muds in today's tropical oceans accumulate at a rate of one foot thickness per one thousand years. These muds are formed by mechanical breakdown of carbonate containing sea creatures. Modern muds are believed by evolutionists to provide an excellent example of how ancient lime mudstones ("micritic limestones") were accumulated in Grand Canyon. Even some creationists believe that the evidence from lime muds is so convincing that one must certainly believe in long ages of slow deposition for Grand Canyon limestones
This is essentially the standard geological theory for the formation of carbonate rocks but is it correct?
Austin continues: ‘There are strong dissimilarities, however. Modern "shallow water" lime muds are dominated by "silt sized" crystals (approximately 20 microns in diameter) of the mineral aragonite (most contain 60 to 95% aragonite, and 0 to 10% calcite) derived from disaggregation or abrasion of skeletons of marine organisms. Ancient lime mudstones ("micritic limestones") are abundant in Grand Canyon, and are dominated by "clay sized" crystals (less than 4 microns in diameter) of the mineral calcite (nearly 100% calcite and/or dolomite) with "sand sized" and larger skeletal (shell) fragments floating in the fine crystal matrix… Micritic limestones, composed essentially of calcite, have textures quite different from those of the aragonite dominated modern lime muds that long have been regarded as their precursors…Modern carbonate sediments contrast sharply in their chemistry and mineralogy with ancient carbonate rocks… At the present time, it would be inappropriate to suppose that the scientific evidence requires that ancient fine-grained limestones were derived from lime muds resembling the muds being deposited slowly in modern tropical seas. Evolutionists may make the assumption, but the facts do not justify it. In the words of F.J. Pettijohn, "The origin of micrite is far from clear
Austin then counters a common objection; ‘Critics… say that many abundantly fossiliferous limestones are organically constructed "reefs," which were accumulated slowly along the edge of an ancient sea… because it took thousands of years to construct a huge wave resistant framework, as innumerable generations of organisms chemically cemented themselves, one on top of the other… The most extensive study of Grand Canyon limestone was by McKee and Gutschick. They admit, "Coral reefs are not known from the Redwall Limestone." Concerning laminated algal structures (stromatolites) which might form slowly in tidal flat environments, they say, "the general scarcity or near absence of bottom building stromatolites suggests that places generally above low tide are not well represented
So, if the Redwall Limestone deposits of the Grand Canyon did not form over millennia in calm tropical seas, how did they form? A clue can be found at Nautiloid Canyon.
Austin explains; ‘Evidence of rapid deposition and burial of fossils is found in the Redwall Limestone. Along the Colorado River at Nautiloid Canyon, just north of Grand Canyon, the Redwall Limestone contains large fossils of nautiloids—"squid like" marine animals that possessed a straight shell, sometimes over two feet long. The long, slender shells of numerous nautiloids, in Nautiloid Canyon, have a dominant orientation, indicating that current was operating, as "fine grained" lime mud accumulated.
'Not all limestones of Grand Canyon are fine grained. Some contain coarse, broken fossil debris, which appears to have been sorted by strong currents. The Redwall Limestone contains coarse, circular disks (columnals) from the stems of crinoids—marine animals which lived in a cup, or head, attached to the stem. Evidently, water currents winnowed the finer sediment away, leaving a "hash" of crinoid debris. Occasionally, the heads of crinoids are found embedded in the coarse, circular disks. Sometimes these occur in deposits of inclined bedding (cross beds), which imply strong currents. Because modern crinoid heads in today's ocean are susceptible to rapid breakdown when these organisms die, we conclude that rapid burial is needed to produce fossil crinoid heads.
'Evidence of current transport of lime sediment is provided by quartz sand grains, which are found embedded in the fine-grained matrix of many limestones. These quartz sand grains are common in the Kaibab Limestone of Grand Canyon. They are even known in the Redwall Limestone. Because the quartz sand grains cannot be precipitated from seawater, they must have been transported from some other location. Any water current fast enough to move sand grains would be able to move lime mud, as well. These quartz sand grains argue that the Kaibab Limestone was accumulated from sediment which had been transported by moving water, not simply deposited from a slow, steady rain of carbonate mud in a calm and placid sea
The fossils of Nautiloid Canyon tell a story of catastrophic burial. One in which these creatures became trapped in a thickening flow of carbonate material eventually cementing them in the rock record. How could this not be the case? Otherwise we have to assume that individual nautiloids neatly aligned their conical shells during death, over thousands and millions of years, waiting to be fossilised!
We can picture a scenario; an external agent disrupts the Earth’s rotation and the planet quakes, huge tidal waves scour and redeposit surface material, flora and fauna are caught in the cataclysm and deposited in huge ‘graveyards’ the planet over. As tidal waves push far inland they remodel existing coastlines, depositing their load in an organised manner as they do. A diagram of such a marine transgression can be seen on page 3 of the document ‘Sedimentological Interpretation of the Tonto Group Stratigraphy’ by Berthault available for download at: http://efficalis.com/sedimentology/wp-c ... -Group.pdf
But, what and where was the source material that formed the limestone deposits mentioned in the paper by Austin?
Carbonatites are an unusual type of rock consisting of greater than 50% carbonate minerals and have a global distribution. The only active carbonatite volcano is Ol Doinyo Lengai in Tanzania; the lavas of Ol Doinyo Lengai are rich in the rare sodium and potassium carbonate minerals and are known as Natrocarbonatites. Other forms include Ferrocarbonatite, Calciocarbonatite and Magnesiocarbonatite.
Carbonate rocks are not usually thought of as being igneous in origin but the idea is not a new one.
From an article in Nature (142: 704-705, 1938) ‘Limestones as Eruptive Rocks’, we read ‘…so early as 1892, some limestones occurring in the form of dykes and cutting the volcanic rocks of the Kaiserstuhl in Baden, were described by A. Knop, and three years later A. G. Hogbom described limestone dykes in a region of alkali-rich intrusive on the island of Alno in Sweden. Hogbom also recorded calcite as a primary mineral in some rocks at Alno, and there were other descriptions of primary calcite in alkali-eruptive rocks from Canada and India.’ And ‘The most convincing new evidence comes again from Alno, where the rocks are now far better exposed than they were at the time of Hogbom’s visits forty-three years ago. They have been studied thoroughly by Dr. Harry von Eckermann, of Stockholm, who opened the discussion at Cambridge. A large area of alkali-intrusives (nepheline- syenites and ijolites) cuts the Precambrian gneisses and is probably late Jotnian in age. Around the contact with the gneiss (which is altered) crystalline limestones appear, and outside the neck of the intrusive rocks there are calcitic and dolomitic dykes which are shown to be cone-sheets dipping towards two deep central foci. From the inclination of the cone-sheets the focus of the calcite dykes can be shown to be at 1-2 km below the present surface, and that for the dolomitic sheets at 6-7 km. The geology of the country near Alno is well known, and von Eckermann regards it as certain that for hundreds of miles around and to great depths there is no trace of sedimentary limestone in the Archaean rocks of earlier age than the alkali-intrusives. All the evidence points to a magmatic origin for these limestones at Alno
Now for some speculation. The western Pacific Ocean is littered with seamounts and guyots. Deep sea drilling of Eniwetok Atoll in the Marshall Islands unveiled a 4,133 to 4,608 feet (1,260 to 1,405 m) thick carbonate cap. To quote Michael Oard, ‘Legs 143 and 144 of the Deep Sea Drilling Project drilled into the tops of a number of guyots in a large area west of the Hawaiian Islands centred at about 18°N and 180°E,and in the Marshall Islands centred at about 10°N and 165°E. The former area includes the submarine Mid-Pacific Mountains. Resolution Guyot with suggested perimeter reefal mounds, supposedly mimicking an atoll, was drilled in the Mid-Pacific Mountains. The scientists discovered that numerous guyots in the Mid-Pacific Mountains were capped by thick carbonate, just like on Eniwetok Atoll. The carbonate caps range between 3,000 to 5,250 feet (900 to 1,600 m) thick and lie over basalt lava. The thick carbonate was a surprise
Could it be that the guyots and seamounts of the western Pacific Ocean are all that remains of a former carbonatite/carbonate platform; a platform that was easily eroded by wave action during a cataclysm, the erosional products of which were transported far to the east to be deposited on a pre-existing landmass? Were Calciocarbonatites and Magnesiocarbonatites eroded re-worked and deposited as limestone and dolomite? If so, then perhaps limestone and dolomite should be re-classified as ‘catastrophites’!
1. http://www.nasa.gov/mission_pages/deepi ... GUqfMlqxeY
2. Austin, S. A. 1990. Were Grand Canyon Limestones Deposited by Calm and Placid Seas? Acts & Facts. 19 (12).
5. Milton, R. 1992. The Facts of Life