Published:January 01, 2006
- PDF LinkChapter PDF
Lionel L. Siame, Didier L. Bourlès, Erik T. Brown, 2006. "Preface", In Situ-Produced Cosmogenic Nuclides and Quantification of Geological Processes, Ana María Alonso-Zarza, Lawrence H. Tanner
Download citation file:
As accelerator mass spectrometric techniques matured in the 1980s, measurement of the exceedingly low levels of cosmogenic nuclides present in natural materials became relatively routine. These new analytical capabilities led to expansion of the application of cosmogenic nuclides in earth sciences, as manifested by the rapid increase in peer-reviewed publications (Fig. 1). Since the mid-1990s, most of this growth came from studies utilizing in situ–produced cosmogenic nuclides, which accumulate within surface rocks and soils during exposure to cosmic rays. In situ–produced cosmogenic nuclides can provide chronologies of environmental change over the past few thousand to several millions of years, and may be used to quantify a wide range of weathering and sediment transport processes. These nuclides are thus now used across a broad spectrum of earth science disciplines, including paleoclimatology, geomorphology, and active tectonics. As chronometers, they have been successfully applied to determine: (i) age, extension, and dynamics of glaciers and ice-shields; (ii) the timing of riverine responses to climate change or tectonic movement; (iii) the timing of landslides; (iv) ages and process rates of landscapes; and (v) ages and rates of earthquake fault displacements. As tools for quantitative study of surface processes, they may be used to evaluate collapse, denudation, burial, bio-turbation, and soil creep. They may also provide a qualitative basis for distinguishing allochthonous from autochthonous materials. In addition, new methods are being developed to measure cosmogenic nuclides in a broader suite of mineral phases (e.g., 10Be in sanidine and carbonates, 10Be and 36Cl in clinopyroxenes). Study of other lithologies will permit application of wider range of surface environments, expanding both spatially and temporally their applications. A recent review article on cosmogenic nuclides (Gosse and Phillips, 2001) included a compilation of studies that employed cosmogenic nuclides; to update that reference list we propose a compilation of the most prominent papers published since their review article.
Recognizing the growing interest in this field, a session titled “Application of Cosmogenic Nuclides to the Study of Earth Surface Processes: The Practice and the Potential” was held during the 32nd International Geological Congress (Florence, 21–28 August 2004). This symposium was not only aimed at researchers already applying cosmogenic nuclides but also at scientists whose research might benefit from cosmogenic nuclide analyses, but who have little knowledge of the technique. The creation of a Geological Society of America publication built around the philosophy of the session in Florence was then suggested by Abhijit Basu (Indiana University; GSA books science editor). The present volume represents the fruits of that endeavor.
This book is organized around sections that focus on specific aspects of the utilization of cosmogenic nuclides in earth sciences. The first section presents development of new methods for application of in situ produced cosmogenic nuclides. The article by D. Granger reviews the development of burial dating methods over the past 50 years and presents ways in which multiple cosmogenic nuclides with differing decay rates can be used to quantify the time since burial of rocks in a range of geological settings. The paper by R. Braucher et al. presents new perspectives to extend the time span and erosion rate range quantifiable in carbonate-rich environments, and provide new insights for the possibility of deciphering complex exposure histories by differential radioactive decay over several m.y. in mafic environments. The second section is dedicated to glacial geology. J. Briner et al. and S. Ivy-Ochs et al. review the application of in situ cosmogenic nuclides to study of the Laurentide Ice Sheet during the last glacial cycle and of the timing of glacial advances in the northern Alps, respectively. The third section deals with active tectonics, focusing on applications of in situ–produced cosmogenic nuclides to constrain slip rates of active faults in Asia. F. Ryerson et al. present a review of their studies in Tibet and discuss the apparent disparity between geomorphic and geodetic slip-rates. J.-F. Ritz et al. present an updated synthesis of morphotectonic studies that quantify active tectonics along the Gurvan Bogd mountain range in the Mongolian Gobi-Altay. The final section is dedicated to landscape development. A. Heimsath's paper focuses on the use of cosmogenic 10Be and 26Al, extracted from quartz in bedrock, saprolite, and detrital material to quantify sediment production or erosion rates and processes. The paper by R. Sewell et al. presents the application of exposure dating using cosmogenic nuclides to natural terrain landslides in Hong Kong.
We would like to acknowledge all the people that greatly helped us in editing the present book. At the Geological Society of America, we thank Sara Colvard, Abhijit Basu, and the GSA publications staff for their constant help during the editing process. We also would like to thank the individual reviewers whose constructive and helpful comments greatly improved this work.