ABSTRACT: Using Short Wave Infrared (SWIR) Spectroscopy for Stratigraphic Mapping: Paris Basin, France

HAUFF, PHOEBE, Spectral Research, Lafayette, CO, MEDARD THIRY, Ecole des Mines de Paris, Fontainebleau, France, and TERRY COCKS, Integrated Spectronics Pty Ltd, Baulkham Hills, Australia

The SWIR technique described here originated with spectral remote sensing applications. SWIR is particularly sensitive to sedimentary minerals such as clays, carbonates, sulfates, hydroxides, and iron oxides and to hydrocarbons. SWIR detects octahedral layer bonding, water, and hydroxyls and can be used, after training, to differentiate layer percentages of interstratified clay species such as illite/smectite and kaolinite/smectite. Recent developments in technology from Australia have made it possible to easily transport the method from the laboratory to a portable, hand-held instrument that can be taken to the outcrop and the core shed. Data collection is rapid (30-90 seconds per sample), making this an efficient identification and screening technique. The integrated method proposed by this research combines X-ray diffraction and chemical and thermal analysis to construct an informational data base. Utilizing this data base, the portable instrument can take in situ readings in the field, identify the mineral phases present, and plot this spectral data against stratigraphic columns originated from core or outcrop information.

Field tests were run in the Paris basin quarries in the summers of 1990 and 1991. Within 100 km of Paris an entire paragenetic sequence of kaolinite/smectite interstratified clays exists that defines diverse environments. Changes across the basin in the Eocene Argiles Plastique Formation were mapped and show development of smectites in weathering profiles above a flint-bearing chalk through the interstratified kaolinite/smectite clays produced from alkaline leaching to kaolinites created in the acidic environments associated with argillaceous and sandy sediments in deltas. Samples analyzed are from both outcrop and core.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)