It was one of the most rewarding projects of my career as a biostratigrapher. It was August 2011 and I analysed a microplankton slide for the first time while four geologists crowded behind me, peeking over my shoulder, fidgeting nervously, waiting for my assessment of the fossil assemblage. They asked, ‘How old is it? Have you found anything? Is it older than Palaeocene?’ One could sense the anxiety in their voice, as if they were afraid the microfossils would not agree with their expectations.
The sample under my microscope was very important. However, the palaeontologist must be street-smart when communicating with petroleum geologists. The latter are generally not interested in the nuts and bolts of palaeontology. Understandably, they want conclusions, not morphological details. They want to know ages and depositional environments, not Latin and Greek names. They want chronostratigraphic certainty, not the intricacies of taxonomy.
I had become accustomed long ago to lighthearted teasing about dinoflagellates from non-biostratigrapher co-workers. The tongue-in-cheek remarks were often hilarious, and contributed to a healthy, congenial working environment. Nevertheless, I had never thought I would see the day that my colleagues would grovel before my feet, begging to share in the knowledge that marine microplankton provide. I found their sudden respect for my science intensely rewarding. I savoured the moment.
The organic residue sealed in transparent polymer on the slide in my microscope had been submersed in hydrofluoric acid only a few minutes earlier. We dissolve the carbonates from sedimentary rock, then dissolve the silicates. What remains is the acid-resistant organic content of the sediment: microplankton, terrestrial spores, pollen, and the ever-present organic background debris. The acid digestion technique underpins the science of palynology.
The organic residue I was analysing originated from a claystone sample that we had retrieved the previous week from a seabed outcrop near the base of the Jan Mayen Ridge. Four hundred kilometres northeast of Iceland, sedimentary rocks outcrop along the steep cliffs of the ridge in 2000 m water depth. We had high-resolution seismic data across the ridge, but we had no information on the age of the seismic reflectors. If we knew the ages of the outcropping beds, we could assess the petroleum potential of the unexplored region south of the Jan Mayen micro-continent. In the summer of 2011, we successfully completed the first geological sampling mission in the area using a remotely operated vehicle, or ROV.
An exploration company had used a gravity corer to sample the outcrops years earlier. However, gravity core tubes are notorious for deflecting off steep inclines. In addition, because the core tool occasionally drops to the sea floor along a helical or meandering trajectory, the geographic coordinates of the sample point can have a large error ellipse on a slope. The ROV with high-resolution cameras and acoustic positioning transponders proved very successful in this respect.
After a few minutes of microscopy, and a few ‘ohs’ and ‘hmms’ as I peered into the oculars, I finally answered ‘yes’ to the geologists’ question, ‘Do you know the age?’ ‘Well then tell us!’ they insisted. ‘But if I tell you, then I will no longer be the only person on the planet who knows the age of these strata! I quite like being the only person who knows.’
I realized that I was experiencing the peak of my career in palaeontology. After all the years of friendly jabs, I was getting my revenge!
To my co-workers’ great jubilation, I proclaimed that the sample’s age was Early Cretaceous, around the Valanginian–Hauterivian boundary. They were elated because it proved that there are Mesozoic sediments on the Jan Mayen Ridge. Unfortunately, their joy was short lived. A few days later, high-resolution video from the ROV showed that samples having ages older than Eocene were not from the outcrop but were lying loose on the sea floor. They were part of the enormous debris field of dropstones from icebergs sourced from Greenland. Samples that the ROV’s mechanical arm broke off the outcrop consistently contained Eocene and Early Oligocene dinoflagellate assemblages. It was an important discovery.
The path to robust biostratigraphical interpretations is often long and winding, but the fun is in the adventure of discovery of the earth’s deep history. I feel very fortunate to be working with these lovely fossils. Dinoflagellate evolution produced innumerable fantastic morphologies, and it is always a pleasure to share them with those who appreciate them!