Consider the situation. Scientists discovered a sedimentary layer of earth with high amounts of the element iridium. This layer was laid down about the time at which the dinosaurs went extinct. Iridium is rare in Earth’s rocks, but it is commonly found in meteorites. Scientists suggested that a large meteor impact caused a layer of dust to envelope Earth, which may have resulted in the extinction of the dinosaurs. Which type of scientific reasoning is being described in the situation?

Deductive scientific reasoning is a process to reach to a conclusion. In order to arrive to a conclusion, there should be premises to sustain that conclusion. In other words, deduction is a proces by which specific information can lead to infer or draw the consequences from them.

For instance in this situation here, the conclusion scientists have arrieved is "Scientists suggested that a large meteor impact caused a layer of dust to envelope Earth, which may have resulted in the extinction of the dinosaurs."

To arrive to this, they have the premises that sustain it: the layer with the amout of iridium that was commonly found in meteorites, and also that this layer was found about the time dinosaurs got extinct. Basing on this theory they draw the conclusion.