Marine Geosciences Division – M.J. Keen Medal – Reinhard Hesse

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The Michael J. Keen Medal 2009 Recipient:  Reinhard Hesse

Nomination of  Dr. Reinhard Hesse by Dr. David Piper

We wish herewith to nominate Professor Reinhard Hesse of the Department of Earth and Planetary Sciences of McGill University for the 2009 Michael J Keen award of the Marine Geosciences Division of the Geological Association of Canada. In support of this nomination, we review below the contributions that Dr Hesse has made to the advancement of marine geoscience and related fields. His CV is attached to this document. I have been assisted in preparing this document by Dr A.E. (Willy) Williams-Jones of McGill, who also supports this nomination. We have also attached the necessary letters of support from a wide range of colleagues and former students, attesting to the broad international recognition of his work.

Reinhard Hesse is an internationally renowned earth scientist who has made major contributions to the disciplines of sedimentary and marine geology through discoveries of lasting significance associated with his study of:

(1) the Northwest Atlantic Mid-Ocean Channel (NAMOC) system of the Labrador Sea as a continuation of the subglacial drainage system of the Laurentide Ice Sheet (LIS) of North America, 
(2) sediment supply to and redistribution on the Labrador continental slope and rise in the vicinity of one of the main ice streams of the LIS in the Hudson Strait,
(3) pore-water anomalies in gas-hydrate bearing sediments on the continental margins (gas-hydrate dissociation hypothesis),
(4) diagenesis and anchimetamorphism of fine-grained argillaceous and siliceous sediments, and
(5) turbidite sedimentation in ancient flysch troughs of orogenic belts.

(1) His pioneering work on the NAMOC and its tributary system in the Labrador Sea, one of the longest deep-sea channels in the world, links deep-sea sedimentation to continental ice sheet drainage. He and his team mapped major parts of the 3800 km long channel using sonar side scanning equipment and discovered geomorphologic features reminiscent of those of large rivers on land but also showing distinct differences such as low-sinuosity meanders, asymmetric submarine levees that are 10 times higher than subaerial levees, meandering talwegs, and yazoo-type tributary channels. These spectacular features provided the key for understanding transport processes in deep-sea channels and their natural levees. He proposed that a newly discovered braided sand plain (one of the largest sand bodies on Earth) was the product of catastrophic subglacial lake outburst flooding from the Hudson Strait during periods of intensified iceberg drift known as Heinrich events. The latter correlate with major, short-duration perturbations in the global climate system (cooling events followed by rapid warming) during glacial times, which are documented in Greenland ice cores and supported by the paleoclimatic information extracted by Hesse and his students from deep-sea sediment cores. A major contribution of his work was the discovery of a unique depositional facies of lofted sediments comprising ice-rafted debris (drop-stones) in graded muds which are only deposited during Heinrich events.

Another important finding by his group was that of an additional Heinrich Event, 5a, between known events 5 and 6, which provides strong support for the binge-purge model of ice sheet growth and decay (Rashid et al., 2004). It halves the anomalously long time interval (15000 yrs) between two successive events, which then is comparable to the average recurrence interval of 7000 yrs required to restore an ice sheet to its full thickness (3-4 km) after collapse during a Heinrich event.

(2) Dr Hesse’s piston-core and reflection seismic studies on the Labrador Slope have drawn attention to the significance of fresh-water turbid surface plumes issued from ice-tunnels which deliver fine-grained sediments to the continental slope adjacent to ice stream and glacier outlets. They have also shown how this sediment is redistributed to the lower slope and basin by slumping, debris flows, turbidity currents and contour currents, and how erosion by headward gullying and progressive upward canyon branching dominates the upper slope. As a result of this work, the sedimentation processes that shape the slope and control the facies distribution were better established in the Labrador Sea than on any other glaciated continental margin and have become an essential reference for related studies around Antarctica and elsewhere.

(3) In a landmark paper with Harrison (1981) stemming from his participation in the Deep Sea Drilling Project (DSDP) Leg 67, Dr Hesse proposed that the then recently discovered methane hydrate zones (a sleeping time bomb for global warming and possible next major source of fossil fuel) can be recognized by characteristic anomalies in the pore water chemistry caused by hydrate melting. Building on this early work, Hesse and collaborators in Ocean Drilling Program (ODP) Leg 164 later succeeded in developing the analysis of pore-water chemistry into what has now become the best method for estimating hydrate concentration and distribution in the subsurface. These two studies have since been cited in virtually every new paper on the subject.

The study of early diagenetic pore-water, this time in Ordovician rocks of the Gaspé Peninsula, was the source of another breakthrough when Hesse and his students demonstrated that some of the carbonate concretions started to precipitate in sediment so close to the sea floor (within a few cm) that the oxygen isotopic composition of the sea-water can be read directly. The findings helped resolve a long standing debate by supporting the hypothesis that Ordovician seawater was depleted in the heavy isotope and evolved to its modern value through water-rock interaction at mid-ocean ridges. Oxygen-isotopic analyses were also the focus of an important study of illite/smectite clays in the Beaufort-Sea/Mackenzie Delta where Hesse and students discovered a depth trend that they were able to relate to secular paleoclimatic changes in the Arctic from the Cretaceous to the Pleistocene.

Hesse has participated repeatedly in DSDP and ODP, two mega-programs in the earth sciences that serve as a model for international scientific cooperation. He was one of the first participants in the DSDP from Canada and was a member of the Leg 20 team (1971) in the West Pacific at a time when Canada was not yet a member country of the project. Moreover, as a member of this team, he was the lead author of a pelagic sedimentation model for the Pacific Ocean predicting the type of sediment reaching circum-Pacific subduction zones and affecting the sediment-derived geochemical signatures of subduction-zone magmas (Hesse et al., 1974). As a result of his participation in the expedition he was also able to study the diagenesis of an Early Tertiary seamount oolite recovered from a sunken atoll in the West Pacific, and provide evidence supporting the notion that earliest Tertiary seas were aragonite- rather than calcite-producing, implying a relatively low partial pressure of CO2 in the atmosphere as at present. In the mid-1980’s he was Canada’s representative on the Pacific Ocean panel of ODP.

(4) Over the last two decades, Hesse has enjoyed a very productive collaboration on clay diagenesis with H. Vali, an expert in transmission electron microscopy, whom he brought to McGill as a senior research associate from Germany. (Professor Vali is now Director of McGill’s Facility for EM Research). Together, they developed a new technique to study expandable clays after treatment with n-alkylammonium ions in ultrathin sections under high-resolution TEM which represented a breakthrough, referred to by some as the ‘magic bullet’ of direct TEM imaging I/S. This technique combined with other advanced methods (cryofixation; freeze etching) was used by his students to characterize the evolution of I/S mixed-layer clays during burial diagenesis in offshore and onshore oil wells (Beaufort Sea-Mackenzie Delta, Jeanne d’Arc Basin) It also enabled them to extend the range of measurable illite crystallinity (IC) of argillaceous rocks to include the loss of the few percent of smectite layers remaining during high-grade diagenesis/low-grade metamorphism, something which had not been possible with conventional X-ray diffraction methods. These methodological advances also provided the tools needed to address problems of clay diagenesis in the Appalachians and St. Lawrence Lowlands which lead to the production of diagenetic/metamorphic maps and the discovery in Quebec City and adjacent areas to the southeast of an inverted pattern in which lower grade rocks with petroleum potential occur in nappes and thrust sheets below sediments in higher grade units that matured beyond the oil “window”. In addition to its tectonic importance, the work has also helped guide exploration in the area – there are now several producing wells in the region – and in conjunction with fluid inclusions has shown that about 4 km of Paleozoic sedimentary cover has been eroded from the St. Lawrence Lowlands since the Cretaceous. Other notable contributions in the field of diagenesis include two widely cited papers on the origin of chert (Hesse, 1988, 1989; 85 citations) and several key studies of sandstone diagenesis in present-day offshore areas (e.g.,Hibernia oilfield).

(5) Some of Hesse’s most enduring work has been in the study of deep water turbidites in mountain belts which he began at the Technical University of Munich (TUM), Germany and for which he set standards not previously matched. His study of individual turbidites in the Rhenodanubian Flysch Zone of the East Alps, representing long distance tracers of single depositional events crossing different tectonic units, was a major breakthrough that paved the way for reliable palinspastic reconstructions in a complex thrust fold-belt. In a paleobathymetric study that added the third dimension to the paleogeographic reconstructions he went on to show that the turbidites had been deposited in very deep water below the Cretaceous calcite compensation level (CCL), most likely in a deep-sea trench (Hesse & Butt, 1976). whereas other smaller turbidite basins that were riding piggy-back on the nappe of the Northern Calcareous Alps were located above the CCL. These contributions earned him the Habilitation (D.Sc. degree) and the Credner Award of the German Geological Society. After arriving in Canada, Hesse extended his work on deep water sediments to the Taconian and Acadian orogenic belts of the Northern Appalachians, where he and his students established the facies relationships between turbidite channel and overbank deposits on the Cambrian continental margin of North America and in a Devonian orogenic shale basin as well as the relationship between provenance areas, sea-level change and turbidite petrology.

Dr Hesse’s greatest strength is a breadth of approach to problems in and marine geoscience that is matched by few in any field. He has explored to equal depth the problems of transport and deposition of clastic sediments and their diagenesis at a time when specialization has permitted most of his contemporaries to master only one of these fields. Most importantly, his contributions to knowledge have been fundamental, numerous and appear in 100 widely cited peer-reviewed publications that have made his a “household” name in the field of marine geoscience. If he has one weakness, it is that he tends to “hide his light under a bushel” which may explain why he has received less formal recognition than colleagues of comparable merit.

I would also emphasise, from my personal knowledge, the dogged determination that Reinhard has shown throughout his long career to work in one of the meteorologically most unpleasant areas of the Earth, the Labrador Sea. He was always convinced of the importance of this Canadian sea for sedimentology. His work laid the foundation for more recent studies on paleo-oceanography of the region. It is also important to view his contributions from the context of his times: in the 1960’s, for example, no-one could understand that muds might be deposited from turbidity currents; in the 1970’s, marine geology was carried out with only transit satellite and flaky Loran-C navigation. It was against this intellectual and technical backdrop that Reinhard brought consistent thoroughness of interpretation and a stream of new ideas. At the same time, the artificial barrier of the coastline has never stopped him from applying fundamental principles of physics and chemistry to geological problems. In the scope of his interests and his search for new ideas, he resembles Mike Keen.

In conclusion, Reinhard Hesse is one of the foremost marine geoscientists of his time and a most worthy candidate for the Michael J. Keen Medal of the Marine Geosciences Division of GAC.

Yours sincerely,

David J.W. Piper
Research Scientist, Geological Survey of Canada

A. E. (Willy) Williams-Jones
Professor, Earth and Planetary Sciences
McGill University

Recipients of the Michael J. Keen Medal may be a Canadian or a non-Canadian who have made a contribution in Canada or with a distinctively Canadian flavour. For more information please see: http://www.gac.ca/wp/?page_id=13345

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