Final answer:
Igneous rocks like granite and basalt form from cooled magma or lava, with textures based on cooling rates. Sedimentary rocks like sandstone are created from compacted sediments, often holding fossils that reveal past environments. Tectonic settings influence rock types, with limestone indicating passive settings, and certain environments better preserve fossils.
Step-by-step explanation:
Different types of igneous rocks are formed from the cooling and solidification of magma or lava. For example, granite is a type of intrusive igneous rock that forms beneath the Earth's surface where the magma cools slowly, allowing large crystals to form. Basalt, on the other hand, is an extrusive igneous rock that forms from lava that cools quickly on the Earth's surface, leading to a fine-grained texture.
Sedimentary rocks, like sandstone and shale, are often formed in environments where sediment is deposited, such as riverbeds or ocean floors. Over time, sediment layers accumulate and are compacted and cemented, turning into sedimentary rock. The presence of fossils within sedimentary rocks often indicates the ancient environments they were deposited in.
Tectonic environments play a vital role in determining the types of igneous rocks found in an area. For instance, volcanic arcs related to subduction zones are often associated with andesite and diorite. Igneous rocks can also give geologists insights into past tectonic activities; for instance, limestone formations typically imply passive tectonic settings.
When it comes to sedimentary environments conducive to fossil preservation, anoxic environments that inhibit decay and wide sediment deposition areas, such as river deltas, are ideal. Harsh conditions, like high energy areas with strong currents that could potentially break down remains, are less favorable for fossil preservation.