Final answer:
A sedimentary rock containing pyrite is more likely to have been deposited in a setting with a lot of organic matter delivered to the seafloor due to the formation of pyrite in oxygen-poor environments.
Step-by-step explanation:
A sedimentary rock containing pyrite is more likely to have been deposited in a setting where there was organic matter delivered to the seafloor. This is because pyrite forms in oxygen-poor environments, such as the seafloor where dead animal and plant remains settle. In these environments, organic matter can accumulate and be preserved without undergoing decomposition.
Moreover, organic sedimentary rocks, which are formed from the accumulation and lithification of organic matter, are often associated with low-oxygen environments. The presence of pyrite in these rocks indicates the past existence of an anoxic, sulphur-rich environment, which would align with a high input of organic material.
Therefore, situations where we find sedimentary rocks with pyrite usually signify that there was initially significant organic material provided to the seafloor, which, due to low levels of oxygen, did not fully decompose and allowed for the formation of pyrite