Increased water temperature leads to a loss of carbon dioxide (warmer water can hold a smaller amount of dissolved gases) and therefore enhances the precipitation of calcium carbonate which crystallises as mineral calcite or aragonite.
Why is it important? Agitation by waves matters because forming ooids need to be in motion to make them grow evenly on all sides. Ooids form in a wave-agitated water, which is usually warm. A famous example of non-marine ooid sand is on the shores of the Great Salt Lake in Utah. Non-marine ooid sands exist also in some saline and freshwater lakes, caliche soils, caves, and even in some rivers. Well-known locations where ooid sands are forming are the Persian Gulf, the Gulf of Mexico near the Yucatán Peninsula and the Bahama platform. Most ooids have rounded morphology, but some are elongated or even tabular, reflecting usually the shape of the crystallization nucleus. They have a characteristic concentric layering which resembles the growth rings of trees. Waves move fine sediment particles (quartz grains or biogenic fragments) which act as a crystallisation nuclei upon which mineralized matter starts to grow. Ooids grow in shallow wave-agitated water. Sand grains have usually had just the opposite story - they were once larger. Ooids are accretionary - it means that they have grown to the size they have now. Ooid sand from the Antelope Island, the Great Salt Lake. Larger grains formed the same manner as ooids are called pisoids (just like sand grains larger than 2 mm are called granules). Just like normal sand grains, ooids have a diameter reaching up to 2 mm (usually less than 1 mm). They could be called sand grains, but they are no ordinary sand grains. Ooids are small rounded accretionary mineralized bodies.
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