Rhenium–osmium geochronology: Sulfides, shales, oils, and mantle

Abstract

Re–Os geochronology can be used to date earth materials (e.g., sulfides, shales, oils) previously undatable by other isotopic methods. Of pivotal importance, these materials are directly linked to natural resources, both minerals and hydrocarbon, critical to human civilization. For the immediate future, the challenge is no longer analytical, but geologic. We need to put forward bright and innovative thinking, with the basis for that thinking no longer tied to traditional models, but pointed toward new understanding of how earth’s resources are ultimately generated. Re–Os offers more than geochronology. Acquiring an age for an ore deposit, or shale, gives us the last step in a long process. We have the data in hand to start thinking about “how it came about.” Questions for the future must probe deeper than they have in the past. How can Re–Os be used to link the nascent beginnings of resource formation to the end product that is mined or drained from the earth’s crust for profit? This is not esoteric information, but needed information for responsible exploration in the next century. What conditions, far and wide, deep and shallow, make it possible to liberate metals and hydrocarbons? This is part of the slippery question of source – where and how does it start? Our thinking should not be limited to the lithosphere and hydrosphere, but must include atmospheric processes. These three spheres collectively govern resources. Not surprisingly, they also govern the timely issue of climate change. As a first next step and an easy one to take, reconciling seemingly disparate and non-isochronous data is a good place to start new thinking. There is no such thing as bad data; there is only complexity in data sets that should challenge our imaginations, not prompt us to look only toward the easily interpreted data sets. The barrage of analytical data in the last decade should drive new and thoughtful sampling with different questions in hand.