Development of the Permian Reef

This geological period spans from 300 to 250 years ago. Due to the negative and uneventful transition into this period, organism adapted to the adverse conditions and led to the development of diverse body features. It also affected the distribution of organisms especially during the periods of high sea level stand and low sea level stand. The ramp to rim evolutionary succession is one of the most common statigraphic patterns within a carbonate super sequence of the second order. This process occurs simultaneously with concomitant evolution of stone rims which are bound by rims. Retrograding systems such as the Devonian of the Canning Basin (Playford et al 1929) experience this statigraphic pattern. A deeper comprehension on the extrinsic and intrinsic boundaries on the accumulation of carbonate platform is a vital step in the interpretation and description of the ramp to rim profiles observed as they occur. When the Guadalupe Mountains experienced carbonate accumulation, it was recorded as an 11Myr record of ram to rim shelf platform accumulation. This platform geometry analysis spanned across 30 sequences of high frequency and more than a statigraphic section of one kilometer. The widespread exposures that occurred throughout the Guadalupe mountains and the studies made by several practitioners (Harris & Kerans 2012) have enabled the conclusions of links  in platform geometry, type of carbonate type and the architectures of the slope and systems connected to this factors. When siliclastics were introduced within this depositional system, the carbonate mud factory was displaced which led to the lower slope of the Guadaloupian mountain being starved of the exported mud carbonate. This ultimately led the gradient of the slope increasing and also rushed the transition from ramp to rim. The Delaware Basin and the Midland basin which is directly on its opposite side are divided by a platform of central basin. These three elements represent the main tectonic elements which make up the Permian basin. The Permian basin is compound foreland basin system which has undergone the process of massive subsidence at an accelerated rate during the early Permian period. It is greatly related to the orogenic events experienced in the south west to the northwest region of the compressed Marathon-Ouachita region (Ross 1986) the strata geometry of the Capitan profile transitioned from the goat seep marks into a well defined reef with a rim which had a flat topped platform. In the Capitan fore slopes which exhibit clinoform surfaces, there is an emergence of lenticular bed complexes. These beds are irregular in lateral and upslope directions which are completely different from each other. Also, these lenticular bed complexes sedimental bodies with conical shapes which eventually laterally amalgamate together to form aprons which are strike extensive and lead to the formation of geometries with backfilling. When the profile of the slope undergoes the process of complete backfilling, it leads to the formation of a 50 to 80 meter thick, 400 meter high clinotherms which provide substrates for the margin settings of reefs to prograde over them.

Breccia beds with a thickness of 1 to 3 meters are the smallest of components of backfilled clinotherms. These breccias beds represent singular collapse of thee main parts of the reef margin which has already undergone lithification. Concerning the evolution of reefs, in several environments, the start of the Permian period affected a large number of organisms. However the most affected were marine organisms. This period led to the extinction of more than fifty percent of all invertebrates that existed during that time. The Permian caused destabilization of ecological systems as the dominant organisms diminished in numbers. Permian reefs have undergone massive reconstruction.

Originally Permian reefs were just mounds of mud which were formed from sludge carbonate. These reefs were also composed large skeleton building organisms (Flugel 1994).As a result, Permian reefs have undergone a meticulous beautiful reconstruction which resembles towers spanning across most tropical coastlines. However there emerged some reefs that had undergone more reconstruction and possessed a biotic diversity which was almost close to the modern reefs. These reefs not only exhibited complex structural complexities but also a reef zonation. This reef zonation comprised of fore reef talus which is a remnant shed from the face of a reef, a reef slope a crest, and also a lagoon reef with a flat back.

 However this lagoon reef does not possess a formidable outer framework which is found in contemporary reefs (Wood, 1998).The Capitan Reef of south western Texas and south eastern Mexico is a beautiful example of a contemporary reef (Wood 1998, Scholle, 1999). Permian reefs also comprised of coral building organisms. However these anthozoans were very different as compared to the modern coral building organisms referred to as scleractinians. Anthozoans include corals which develop huge reefs inside tropical waters. Their fossil records are highly diversified which extend back at least to 550 million years. Permian corals evolved in the early Paleozoic period however most of these corals which were either rugose corals or tabulate corals encountered adversity during their evolution. Few of these corals survived until the Permian period had ended (Boardman, 1987).

            Calcareous sponges, bryozoans, problematica and echinoderms were the main organisms that led to the construction of coral reefs. Problematica refers to enigmatic organisms which seem not to have any clear descendants or close relatives when their remains and activities are studied. Classification of these organisms by Paleontologists is said to be problematic because it is tedious and hard to find any clues relating to this organism. The dominant organisms involved in reef reconstruction within the Permian are known as problematicum Archaeolithoporella. As stated above, classification of such an organism is hard and therefore, paleontologists have made various assumptions about its morphology. This organism could possibly be calcareous red algae (Mazzullo and Cys 1977) or even a microbe with calcifying properties (Grotzinger and Knoll, 1995).Consequently, the microbe deposited debris of carbonate on other reef organisms which led to accumulation of mud carbonate.

            This debris is mainly made up of several thin layers. It has been suggested that this debris began growing and accumulating inside the cavities of these reefs. Tubiphytes are another type of problematicum found within the Permian reef. The members of this group mainly concentrated on developing reef structures. Tubiphytes are an abnormal type of foraminifera.   Members of the Foraminifera group are organisms with single cells with shells. In some forms, the protoplasm of this shell covers the exterior parts of the shell. This shell may be made of different organic compounds depending on the species. Calcareous algae such as sea weed and eukaryotes which are organisms with complex cells produce calcium carbonate. This calcium carbonate skeleton is a defensive mechanism which prevents other organisms from grazing them. Their skeleton also plays a huge role in development of the reef structure (Flugel,1994).

During the Paleozoic period, echinoderms such as the starfish possessed tentacles which resembled tentacles. They used these tentacles to attach themselves to the sea floor. Echinoderms in their lifetime construct small skeletons of plates made from calcium carbonate present on the sea floor. These plates are known as ossicles. Upon the death of the echinoderm, the plate parts itself and contributes to other small portions of skeleton of the reef debris. Sponges refer to multi cellular marine organisms which attach themselves to the sea floor by structures known as holdfasts. Some of these organisms build their skeletons form silica and calcium carbonate. Sponges have several tiny needle-like spines known as spicules. When also these organisms die, their calcified plates helped in the construction of Permian reefs.

Bryozoans are organisms which live in colonies. These organisms are small in size and produce an intricate encrusting skeleton. When the Permian period ended, bryozoans experienced great changes in their morphology. Today, although there are many types of bryozoans, they are completely difference from those that existed in the Permian era. During the Permian period, numerous lineages of reptiles which had descended from large amphibians appeared. Geologists have discovered carboniferous deposits which they found when they analyzed some of the reptile fossils found in the Permian era. Synapsids refer to reptiles which highly resemble mammals. They are divided into Pelycosurs and therapsids. These creatures exhibit remarkable transitions in terms of their vertebrae from the reptiles which belonged in the earlier Permian periods into actual mammals. (Hill 1992  P.3). This was approved through a record of fossils which lasted about 80 million years.

Pelycosaurs mostly included herbivores and carnivores which developed an extremely long spine on their spinal cord which supported a membrane. Also pelycosaurs had different sets of teeth. Meanwhile therapsids exhibited more advanced features such as remarkable dentition and impeccable bone structure which resembled that of a mammal. In terms of their skeletal structures, they easily merged with those of mammals with no structural breaks. These organisms were able to regulate and maintain their body temperatures at high levels.In the Permian strata, evidence of the fluctuations in the sea level is well displayed. Changes in climate highly contribute to the rise and fall in sea level. At the base of the Permian era occurrence of sea level fluctuations experienced for short durations but with a large magnitudes was mainly cause dry glaciations. Universal Sea level events are normally marked by four extended low stands.

 Low stands refer to a period when the sea level falls beneath the level of the continental; shelf. Permian has been termed as the best classical model to illustrate the process of carbonate and clastic reciprocal sedimentation (Van siclen) during periods when sea level stand is low, terrigous clastics pass through the continental shelf which leads to high exposure to erosion. Also incised valleys are formed when this occurs. In this model, rapid accumulation of a broad expansive belt of carbonates occurs. Eventually the carbonate evaporates then deposited on the shelf in lagoons and playas. During high sea level stand, grain stone shoals were deposited at the margin of the shelf. During this period, the carbonate deposits accumulate on one particular are in the shelf margin

The formation of the one huge continent known as Pangea, led to changes in the global temperatures and also the emergence of several areas experiencing arid climatic conditions. Also the supercontinent led to the closure of sea ways located in low latitude areas. This led to areas around the North Pole experiencing warm temperatures due to the fact that the warm ocean currents were now deflected into high altitude areas. Glaciation became widespread and persisted throughout the Permian era. During the initial stages when Pangea was formed, collision of landmasses was widespread. This led to formation of new mountains which influenced the terrestrial climates of most regions..Natural habitats for most invertebrates were destroyed, This is because when the continents collided, marine sea ways became closed and some habitats within the ocean became too shallow and isolated for some invertebrates to survive

At the end of the Permian period, volcanism highly influences the climatic conditions of several regions. In north eastern Siberia, there was extensive flooding of basalt which spanned for almost three million kilometers. These eruptions led to the emission of ash into the atmosphere, thus reducing the viability of the carbon dioxide taken by plants from the atmosphere during photosynthesis. The large quantities of carbon dioxide present in the atmosphere at that time combine with oxygen from the oceans .This led to the depletion of oxygen in oceans need by marine organisms to survive. Marine invertebrates which lived in shallow warm waters were hugely affected during the Permian period. During the middle Permian era, a maximum number of species became extinct. The Capitanian age had climate conditions which were not favorable for these organisms. Some tried to adapt but the resilient organisms barely survived the period. This situation just kept on becoming more unfavorable as the levels of diversity of these groups of species plummeted further.

In conclusion in the late Permian period, the carbonate platform of the Guadalupian age contains an 11myr record of an evolution of carbonate ramp to rimmed shelf profile. This evolution had frequency sequences which ranged to 30 frequency sequences. Areas such as the San Andreas experienced this sequence. The change was highly transitional as it took the whole of the Permian period for this profile to be completely achieved. This transitional change occurred due to the siliciclastic accumulation on the slope profiles of Guadalupian slopes which were mainly influenced by the stratic patterns that occurred during this period. This carbonate platform experienced a gradual step in evolution which spanned through almost five transitional models which should be expected during other geological periods that this continuous accumulation of deposits should be strongly assumed that it will take place. Within the earlier sequences, there was an exhibition of a large carbonate shelf profile which contained a mud factory which was highly active. The gradients of the slope ranged for less than 28 meters and contained a broad and clearly defined hemipelagic carbonate mudstone blanket. Processes which involved the flow of gravity even though at the moment are surely present, this processes were not allowed to occur in larger scale than they already had. In the beginning, when the exposure to siliciclastic accumulation along the Guadalupian slope eventually led transgression and accumulation to now occur within the basin. A clearly defined increase in siliciclastic sediments on this shelf profile slope highly links to the starvation of the hemiplegic carbonate which was present on the lower slope wedge. Also starvation led to the steepening of the gradients of the slopes even further.

The main factors that led to transition of reef to rim profile within this platform are divided into siliciclastic sediment accumulation which were connected to the deposition of a high rate of sedimentation along the Guadalupian profile and also a periodic dampening of fine grained production of carbonates enhanced evolution of margins by closing deposition processes of the wedge of the hemiplegic carbonate found on the lower slope. This also facilitated over steepening of the margins. However, the differences of influx in supply of sediments and factory style carbonates were not widely considered during the transition within the ramp to rim transition. Also, the over steepening source that consequently led to collapse of the margin and the pronounced development of a rim reef within the Guadalupian was due to aggradational stacking which occurred for a long period of time. The decrease of the rate of progradation rate which led to stacking of sequences in a vertical manner whether it occurred due to tectonic movements and also extended periods of starvation of the basin created shelf to basin landform and also a margin which was highly unstable and susceptible to collapse.

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