Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris, Carlos Gay García, Clair Hanson, Hideo Harasawa, Kevin Hennessy, Saleemul Huq, Roger Jones, Lucka Kajfež Bogataj, David Karoly, Richard Klein, Zbigniew Kundzewicz, Murari Lal, Rodel Lasco, Geoff Love, Xianfu Lu, Graciela Magrín, Luis José Mata, Roger McLean, Bettina Menne, Guy Midgley, Nobuo Mimura, Monirul Qader Mirza, José Moreno, Linda Mortsch, Isabelle Niang-Diop, Robert Nicholls, Béla Nováky, Leonard Nurse, Anthony Nyong, Michael Oppenheimer, Jean Palutikof, Martin Parry, Anand Patwardhan, Patricia Romero Lankao, Cynthia Rosenzweig, Stephen Schneider, Serguei Semenov, Joel Smith, John Stone, Jean-Pascal van Ypersele, David Vaughan, Coleen Vogel, Thomas Wilbanks, Poh Poh Wong, Shaohong Wu, Gary Yohe

Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change

Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

https://science.sciencemag.org/content/sci/235/4793/1156.full.pdf

Chronology of fluctuating sea levels since the triassic.

A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor.

Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings

http://www.zetaware.com/public/McKenzie_1978.pdf

Some remarks on the development of sedimentary basins

I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Methods in Enzymology.

Preface Acknowledgments Notation 1. Historical development of the concept of isostasy 2. Isostasy and flexure of the lithosphere 3. Theory of elastic plates 4. Geological examples of the flexure model of isostasy 5. Isostatic response functions 6. Isostasy and the physical nature of the lithosphere 7. Isostasy and the origin of geological features in the continents and oceans 8. Isostasy and the terrestrial planets Bibliography Index.

Isostasy and Flexure of the Lithosphere

Subsidence of the Atlantic-type continental margin off New York

The Bouguer gravity anomaly over the Himalayan, Alpine, and Appalachian mountains is characterized by a generally asymmetric gravity “low”, which spans the mountains and associated foreland basins. The minimum of the gravity “low” is generally systematically displaced from the region of greatest topographic relief and shows no obvious relationship to surface geology. In addition, the Alps and Appalachians are associated with a generally symmetric gravity “high” that is unrelated to the topographic relief. Together the gravity low and high form a characteristic positive-negative anomaly “couple”. The steep gravity gradient between the positive and negative couple correlates with the Insubric line and its equivalents in the Alps and the Brevard Zone in the southern Appalachians. This gravity anomaly couple is interpreted as evidence for flexure of the continental lithosphere by subsurface (buried) and surface (topographic) loading. The magnitude of the subsurface load is estimated from the integrated excess mass represented by the positive anomaly and the magnitude of the surface load from the topography. By combining these loads the flexure of the lithosphere and the associated Bouguer gravity anomaly are calculated for different assumed values of the elastic thickness Te of continental lithosphere. The best fitting value of Te for the Himalayas is 80–100 km, for the Alps 25–50 km, and for the Appalachians 80–130 km. The model calculations suggest that the main contribution to the gravity couple in the Alps and Appalachians arises not from surface loads such as thrust sheets and nappes but from subsurface loads. However, in the case of the Himalayas the topography appears to be a sufficient load to explain the observed asymmetric gravity low. When subsurface loads do exist therefore, we would not expect a close correlation between mountain topographic relief and depth to the M discontinuity as required by classical models of isostasy. Rather, the M discontinuity is expected to relate to the center of mass of all the loads acting on the lithosphere. The surface and subsurface loads, inferred from the gravity anomaly, play a major role in the development of mountains and foreland basins. The emplacement of large subsurface loads represents the primary event in the Alps and Appalachians, while in the Himalayas the emplacement of the surface load is the primary event. The emplacement of the subsurface load probably marks the initiation of foreland basin development. The regional characteristics of the basin are controlled by the primary load, while local variations are controlled by the secondary, thrust sheet loads. Subsequent movement of either load will produce migration of the basin depocenter. The origin of the subsurface load is not clear, but its association with the insubric line in the Alps and the Brevard Zone in the Appalachians suggests that it may be related to the “obduction” of crustal blocks/flakes onto the underlying plate during continental collision or possibly to the preloaded crustal structure of the underlying plate.

Gravity anomalies and flexure of the lithosphere at mountain ranges

Cross-spectral techniques have been used to analyze the relationship between gravity and bathymetry on 14 profiles of the Hawaiian-Emperor seamount chain. The resulting filter or transfer function has been used to evaluate the state of isostasy along the chain. The transfer function can be best explained by a simple model in which the oceanic lithosphere is treated as a thin elastic plate overlying a weak fluid. The best-fitting estimate of the elastic thickness of the plate is in the range 20–30 km. Analysis of individual profiles shows significant differences in the elastic thickness along the seamount chain. Relatively low estimates of the elastic thickness were obtained for the Emperor Seamounts north of 40°N, and relatively high estimates for the Emperor Seamounts south of 40°N and the Hawaiian Ridge. These differences cannot be explained by a simple model in which there is a viscous reaction to the seamount loads through time. The best explanation is a simple model in which the elastic thickness depends on age and hence temperature gradient of the lithosphere. The low values can be explained if the Emperor Seamounts north of 40°N loaded a relatively young hot plate, and the high values can be explained if the Emperor Seamounts south of 40°N and the Hawaiian Ridge loaded a relatively old cold plate. These estimates of the elastic thickness along with determinations from other loads on the Pacific lithosphere suggest that the elastic thickness corresponds closely to the 450 ± 150°C isotherm, based on simple cooling models. Thus the large deformations and associated flexural stresses (>1 kbar) at seamount loads do not appear to change appreciably through time. This conclusion is in agreement with subsidence data along the seamount chain and with some gravity observations in the continents.

Anthony Watts

Papers

Isostasy and Flexure of the Lithosphere

Subsidence of the Atlantic-type continental margin off New York

Gravity anomalies and flexure of the lithosphere at mountain ranges

An analysis of isostasy in the world's oceans 1. Hawaiian-Emperor Seamount Chain

Slope failures on the flanks of the western Canary Islands