Trusheim, F., 1960, Mechanism of salt migration in northern Germany: AAPG Bulletin, v. 44, p. 1519-1540.
Ferdinand Trusheim was a paleontologist, but he laid the tectono-stratigraphic foundation to understand salt tectonics. His signal contribution was to develop the tools needed to analyze sequential growth of salt pillows and diapirs. He showed how the tectono-stratigraphy of the flanking strata acts like a tape recorder and tracks salt movement though time. First published in German (1957) then in English (1960), the papers coined the terms "halokinesis".
An objective measure of lasting impact is that Trusheim (1960) has been cited 207 times, with an additional 59 citations for Trusheim (1957). His 1960 paper continues to be cited, though at declining rates because of its age. Books and training courses invariably include a review of the concepts and illustrations presented in the original paper. Trusheim's technique and ideas are familiar to and admired by almost all scientists working on salt tectonics, whether or not they have read his paper.
This paper showed that to understand salt diapirism, you could virtually ignore the internal structure of the diapir and instead focus on how thicknesses in flanking sediments vary spatially and how these thicknesses vary over time. As a result, this paper introduced new concepts to salt tectonics: primary, secondary and tertiary peripheral sinks and turtle structures; variable timing of salt movement on different sides of a diapir in response to local differential loading; pinched-off diapirs (a radical idea at the time); and duplication of post-salt layers on thrust faults with salt. He was among the first to estimate the regional flow rate of salt (0.3 mm/yr). He also made a seminal contribution to understanding the physical control of thick overburden inhibiting diapirism and thick salt promoting salt flow.
Trusheim also provided a sound overview of regional salt tectonics in Germany. He used excellent maps, block diagrams, and charts to illustrate the variable structural styles and periods of movement. His paper overturned the 50-year-old prevailing view in North Germany that salt structures resulted purely from Saxonian tangential tectonic compression. As a petroleum explorationist, he illustrated the paper with several examples of exploratory plays related to salt tectonics and included case histories depicting diverse stages of structural evolution controlling structural and stratigraphic traps.
Trusheim opened his paper with its object: "…to describe and explain the formation of salt stock structures in Northern Germany and to contribute in this way to a better understanding of similar phenomena in other parts of the world." This global application has succeeded. Despite being published in English by AAPG, the concepts were slow to be applied outside of Germany. Once they took hold, for example in Brazil and the US Gulf Coast, most supra-salt exploration targets relied on variations of Trusheim's concepts.
Trusheim was a pioneer, largely working alone. He was the first to use the sedimentary record of surrounding strata to decipher the history of salt flow. This counter-intuitive thinking was a brilliantly innovative breakthrough.
We rate the paper's readability as 10/10. This paper has flawless grammar, despite being written by an author whose first language was German.
Vendeville, B. C., and M. P. A. Jackson, 1992, The rise of diapirs during thin-skinned extension: Marine and Petroleum Geology, v. 9, p. 331-353.
The primary contribution of this paper was the recognition that extension causes diapir growth, instead of vice versa. This recognition provided a key to understanding the process of salt diapir development by combining hitherto separate lines of thought on regional extension and salt diapirism into one self-consistent model.
This paper has been cited some 400 times. In three research volumes on salt tectonics released in the four years following publication of this paper, it was cited in 34 of 56 papers. Many of the citations over the years relate to applied work in oil and gas exploration where the central idea of this paper is clearly adopted. Incidentally, the link established in this paper between extension and intrusion has also been applied in other geoscience disciplines, notably igneous intrusions.
The paper led a shift away from a "halocentric" view of spontaneous, active salt diapirism to a focus on regional tectonics with many salt diapirs originating as local responses to regional extension. This inaugurated the "brittle era" of salt tectonics, in which salt deformation is understood by examining the deformation of its brittle overburden.
This paper is also an excellent example of combining subsurface exploration data with analog-model results and theoretical reasoning to converge on a solution. By reconciling regional tectonic and halokinetic schools of thought into a simple model, this paper demonstrated that by considering a broader perspective, solutions to geological problems can on occasion be straightforward.
This paper undoubtedly had, and continues to have, global impact. The geographical spread of examples in published works that apply the concept of this paper covers most of the world's salt basins and in particular the passive margin salt basins where regional thin-skinned extension is prevalent. A notable feature of citing works are the number of highly-applied case studies published by practitioners and consultants working for hydrocarbon exploration companies, testament to the direct commercial relevance of this work.
This paper ushered in two new paradigms for salt tectonics. First, the cause and effect relationship between a salt diapir and the intruded strata was completely flipped, paving the way for understanding the distribution of salt structures in terms of tectonic frameworks.
Second, the paper made the fundamental observation that diapir overburdens should be considered as brittle material, thereby invalidating many of the previous 50 years' ideas on diapir initiation and growth.
In crisply yet rigorously drawing together a historical perspective, regional examples, analog models and logical analysis with clearly spelled-out conclusions, this paper is an exemplar of scientific geoscience writing. 10/10.
Diegel, F. A., J. F. Karlo, D. C. Schuster, R. C. Shoup, and P. R. Tauvers, 1995, Cenozoic structural evolution and tectono-stratigraphic framework of the northern Gulf Coast continental margin, in M. P. A. Jackson, D. G. Roberts, and S. Snelson, eds., Salt tectonics: a global perspective: AAPG Memoir 65, p. 109-151.
Prior to 1995, existing literature on the Gulf Coast margin consisted of relatively local studies of individual regions or examination of single transects which, even if they were of high quality, did not provide an understanding of the whole margin. The most important contribution made by this paper was to show that integrated regional analysis on a basin scale is not only possible but also critical and extremely valuable. The paper showed that a salt-involved passive margin system can be understood, and described, as a whole, but it needs to be properly characterized, and its lateral changes mapped, because no single dip line can work as a paradigm for the whole margin.
The paper has been cited 133 times but its influence is significantly greater because much of its impact has occurred within exploration companies. Moreover, the details of the regional framework have stood up remarkably well to later data and later work. Although modern seismic data have, of course, revealed some complexities and surprises, the interpretations shown in this paper have proven to be remarkably prescient.
The paper set the bar for regional analyses of salt-involved margins. It demonstrated that we must consider the whole margin, its lateral variability, and its evolution through time: salt basins have complexity in all four dimensions. This lesson – look at the details, think about the big picture – fundamentally changed how both academic studies and exploration of salt basins are carried out.
The paper is specifically about the Gulf Coast margin of the USA, but it set an example of how to put together a regional story that has been successfully emulated worldwide. Many of the citations of this work are in papers that describe other basins in other parts of the world.
This paper is not so much about paradigm change, instead it has established best practice.
We rate the paper's readability as 10/10. This paper has flawless English grammar and is structured in a way that makes complicated geology easy to understand.