* Oceanic crust is constantly recycled: The process of plate tectonics means that oceanic crust is constantly being created at mid-ocean ridges and then subducted back into the mantle at subduction zones.
* Jurassic basalts are likely subducted: Jurassic age basalts, being relatively old, would have likely been subducted long ago.
Where to find Jurassic basalts:
* Ophiolites: These are pieces of oceanic crust that have been uplifted and preserved on land. They often contain sequences of rocks representing the entire ocean crust, including basalts. Ophiolites are the best chance to find Jurassic-age basalts.
* Oceanic plateaus: These are large areas of thick oceanic crust that can be relatively old. They might contain Jurassic age basalts, but these would be deeper within the crust and harder to access.
Challenges:
* Depth: Even in ophiolites, the oldest basalts are often buried deep within the crust. Drilling deep into ophiolites can be very expensive and technically challenging.
* Alteration: Basalts that have been exposed on land for a long time are often altered by weathering and hydrothermal processes. This can make it difficult to study their original composition.
In summary, finding Jurassic-age basalts requires:
* Identifying a suitable location: Ophiolites or oceanic plateaus are the best candidates.
* Deep drilling: Reaching the oldest basalts often requires drilling to significant depths.
* Detailed analysis: Altered samples need careful study to understand their original characteristics.
