Lamont-Doherty Geological Observatory Research Articles

85 ЛЕТ МОРСКОМУ ГЕОЛОГУ Е. Г. МИРЛИНУ

December 16, 2023 to the former chief researcher of the V. I. Vernadsky State Geological Museum of the RAS, Doctor of Geological and Mineralogical Sciences, Evgeniy Mirlin turned 85 years old. The main direction of E. G. Mirlin’s research is the study of lithospheric plates and rifting, mineralogy, geodynamics and minerals, magnetic heterogeneity of the Earth’s crust and the structure of the spreading zones of the Atlantic and Indian Oceans. Dr. Mirlin took part in many expeditions to various regions of the World Ocean, and in 1975, together with colleagues from the United States, took part in an expedition on the ship “Knorr” in the North Atlantic, where the tectonics of the ocean floor was studied using deepsea towed vehicles. He processed experimental data at leading research centers in the USA: the Lamont-Doherty Geological Observatory, the Massachusetts Institute of Technology and the University of California. Awarded orders and medals: in 1982 E. G. Mirlin led the country’s first oceanological expedition to Lake Baikal, where the “Pysis” underwater manned vehicles were used for the first time, as a result of which he was awarded the Order of the Red Banner of Labor. For his great contribution to the geological structure of the subsoil, in 1999 he was awarded the “Excellence in Subsoil Exploration” badge; in 2002 the “Honorary Subsoil Prospector” badge; in 2011 the “Academician A. L. Yanshin” medal; in 2012 – the sign “Mining Glory” of the third degree.

CSEG interview: Leon Thomsen

Leon Thomsen attended the California Institute of Technology, “a small school in Los Angeles—800 students, 800 faculty,” he jokes, with an outstanding geosciences program. Upon graduation in 1964, Thomsen went to Columbia University, and its associated Lamont-Doherty Geological Observatory, from where he graduated in 1969.

Microearthquake Data Elucidate Details of Caribbean Subduction Zone

While the Caribbean is commonly thought of as a tranquil place for a vacation, with turquoise waters and swaying palm trees, it faces devastating natural hazards, including hurricanes, earthquakes, and tsunamis. Hurricanes get their due attention every year with the onset of the hurricane season. To the credit of local authorities, earthquakes and tsunamis began to receive much more consideration in the last quarter of the 20th century. This happened in spite of the fact that damaging quakes and tsunamis may strike any given island only once every century or two. Complicating the development of a long-term earthquake monitoring program, however, has been the diverse political nature of the entities in the Caribbean. The northeastern corner contains two distinct U.S. territories; possessions of Great Britain, France, and the Netherlands; and numerous small independent countries. The U.S. territories in the Caribbean are occupied by nearly 4 million U.S. citizens. Their 500-year written history demonstrates the vulnerability of these rather isolated islands to the effects of major earthquakes. The island of Puerto Rico has suffered from four major shocks with weeks of aftershocks in 1670 ( Mw perhaps 6.5), 1787 ( Mw ∼8), 1867 ( Mw ∼7.3), and 1918 ( Mw 7.3) (McCann et al. , 2002). The last event caused about $25,000,000 in damage (in 1980 dollars) and 116 fatalities. The Virgin Islands have been affected by major seismic events in 1690, 1785, and 1867. The last event caused enough chaos to convince the U.S. government to delay its purchase of the islands for 50 years. Local seismic monitoring in Puerto Rico and the Virgin Islands began in 1975. Monitoring was undertaken by two different organizations, and the two seismic networks spatially and temporally overlapped. The Eastern Network, operated by Lamont-Doherty Geological Observatory (now Lamont-Doherty Earth Observatory, LDEO), reached as far …

Ocean Drilling Program: Recent Highlights and Future Expeditions

During the past year, exploration of the deep ocean floor through scientific ocean drilling has yielded important results with respect to evolution of ocean crust and continental margins and paleoceanography. This paper describes the Ocean Drilling Program's (ODP's) scientific and technical achievements during its ninth year of field operations and discusses areas of future study.

The Lamont—Doherty Geological Observatory Isolab 54 isotope ratio mass spectrometer

The Lamont—Doherty Geological Observatory (LDGO) Isolab 54 is a double focussing isotope ratio mass spectrometer that allows the measurement of thermal ions produced on a hot filament, (thermal-ionization mass spectrometry (TIMS)), secondary ions produced by sputtering a sample using a primary ion beam, (secondary ion mass spectrometry (SIMS)), and sputtered neutrals resonantly ionized using laser radiation, (sputter-induced resonance ionization mass spectrometry (SIRIMS)). Sputtering is carried out using an Ar primary beam generated in a duoplasmatron and focussed onto the sample using a two-lens column. Resonance ionization is accomplished using a frequency-doubled dye laser pumped by an excimer laser. The Isolab's forward geometry analyzer, consisting of an electrostatic followed by a magnetic sector, allows the simultaneous collection of different isotopes of the same element. This instrument is the first to have a multicollector that contains an ion-counting system based on a microchannel plate as well as traditional Faraday cups. A second electrostatic sector after the multicollector is equipped with an ion-counting Daly detector to allow high abundance sensitivity for measurements of large dynamics range. Selectable source, collector, α and energy slits on the instrument allow analyses to be made over a range of mass resolving powers and analyzer acceptances. Recent applications of the instrument have included the analyses of U by TIMS, Hf, Th and Re by SIMS and Re and Os by SIRIMS.

Gas exchange in a contaminated estuary inferred from chlorofluorocarbons

A new method of quantifying mean rates of gas exchange for natural water systems using the distribution of pollutant chlorofluorocarbons (CFCs) is presented. Concentrations of dissolved CCl3F (F‐11), CCl2F2 (F‐12), and CC12FCC1F2 (F‐113) in the Hudson estuary are supersaturated with respect to the remote troposphere by as much as an order of magnitude. The most plausible source appears to be discharges from waste water treatment facilities. Loss of these compounds from the estuary water to the atmosphere occurs both upstream and downstream of the zone of input. Using a multi‐box model, gas exchange coefficients were calculated to be between 2 and 4 cm hr−1 based on the observed concentrations. This rate of gas exchange is similar to values determined in lakes and coastal bays and substantially lower than the mean value for the open ocean.

NADW formation as a branch of the hydrological cycle

The wide interest in the nature and evolution of deep ocean circulation as a key factor to understanding climate change set the stage for a conference devoted to North Atlantic Deep Water (NADW) formation held at Lamont‐Doherty Geological Observatory (LDGO), Palisades, N.Y., from November 11 to 12, 1991. Sponsored by the LDGO Climate Center and hosted by Wally Broecker, about seventy scientists attended. Twenty‐seven invited papers were presented at the 2‐day conference.The rates and paths of NADW formation were the focus of the first day. Bob Dickson, Lowestoft, U.K., summarized the present state of the “northern end” of global thermohaline circulation. In contrast to the view one obtains from many existing numerical models, especially the simpler ones, NADW derives, in reality, from a mixture of distinctly different water masses before it spreads into the world ocean. At most, 50% of the estimated 20 Sv (1 sverdrup = 106 m3/s) of North Atlantic overturning actually comes from the Arctic via the overflows east and west of Iceland; the rest is thought of as recirculating water from the Labrador Sea. The Greenland‐Iceland ridge overflow conspicuously lacks both seasonal and interannual variability in the transport. This is an important constraint for future modeling efforts.

Doubts raised on ocean fertilization with iron

The ability of the ocean waters off Antarctica to absorb significant amounts of atmospheric carbon dioxide after fertilization with iron has been called into question by researchers who have modeled the dynamics of the process. Using a model calibrated with data on atomic bomb-produced radiocarbon in ocean waters, Wallace S. Broecker, of Columbia University's Lamont-Doherty Geological Observatory, Palisades, N.Y., and T.-H. Peng, of Oak Ridge National Laboratory, Oak Ridge, Tenn., calculate that 100 years of completely successful iron fertilization would reduce atmospheric C0 2 by only 10% [ Nature , 349 , 227 (1991)]. That is not enough, they say, to have a positive effect on projected global warming due to the greenhouse effect. The notion that the iron content of some large expanses of ocean determines the biological productivity of those waters was first proposed by John H. Martin, director of Moss Landing Marine Laboratories, Moss Landing, Calif. (C&EN, July 2, 1990, page 21). Martin has shown that ...

Recent crustal movement studies in Aswan region, Egypt: introduction

After the November 1981 earthquake in the Aswan area along the Kalabsha fault, Nubian Desert, studies on its origin were initiated in the Helwan Institute of Astronomy and Geophysics [now National Research Institute of Astronomy and Geophysics (NRIAG) in Helwan]. As a first step an array of seismic stations were established in cooperation with the Lamont-Doherty Geological Observatory and the correlation between the number of seismic events and the water level in Lake Nasser was investigated. In order to understand the eartqquake mechanism, additional information on the crustal deformation due to water load was required, and the International Center on Recent Crustal Movements (ICRCM) was invited to consult in the necessary procedures aimed at recent crustal movement studies around part of the western bank of Lake Nasser. The first local network of horizontal and vertical geodetic measurements was established and measured in 1984. Simultaneously, with respect to the extreme meteorological conditions in the desert, additional investigations as refraction studies, stability of bench marks etc. were initiated. The extension of the network and an increase of repeated measurements first brought results during the last few years. The results of these studies will be reported in the following papers in detail as a homogenous block of scientific communication.

Structural style of intra-plate deformation, Central Indian Ocean Basin: evidence for the role of fracture zones

The structural style of the intraplate deformation developed in the Central Indian Ocean Basin was investigated in an area (78°E–82°E, 0°S–6°S) to the west of the Afanasy Nikitin seamount using an integrated data set of seismic reflection profiles from Edinburgh University and Lamont-Doherty Geological Observatory. The study area contains two fracture zones, which strike ~ 005° E to 010 °E, with oceanic lithosphere (age range ~ 65–78 Ma B.P.) younging westwards across them. No evidence for recent fault activity in the oceanic basement along the fracture zones could be detected in this area, although the close association between intraplate earthquakes and fracture zones elsewhere suggests reactivation of the fracture zones at upper mantle depths in a left lateral strike-slip sense. A statistical study was carried out into the first and second orders of deformation, long wavelength basement undulations and high-angle reverse faults respectivelyand the relationships between them. The orientations of the axes of the undulations vary from 065 ° E to 085 ° E while the high-angle faults strike consistently at 090 ° E to 100 ° E. The results of this analysis suggest that the high-angle faults are the result of the reactivation of two sets of pre-existing spreading-centre normal faults, one set originally facing towards the spreading centre and the other facing away. Furthermore, although the long wavelength undulations are not fault generated, the high-angle faults have modified the basement topography causing the accentuation of some of the basement highs. The observation that the undulations are not fault-generated is consistent with them being of flexural origin (including buckling of the crust and/or lithosphere). Basement undulations are clearly discontinuous across fracture zones and the facing direction of faulting is also offset. This discontinuity, the orientation of the axes of the undulations, the presence of other strong oblique basement trendsand information from regional earthquake studies suggest that the deformation resulted from not only ~ N-S compression as a result of the continental collision between India and Asia, but also left lateral strike-slip along fracture zones caused by the difference in resistance to plate motion between the continental collision to the north and subduction at the Sunda Arc to the northeast.

SYSTEM FOR MEASUREMENT OF 222Rn AT LOW LEVELS IN NATURAL WATERS

1 Lamont-Doherty Geological Observatory of Columbia University, Palisades, NY 10964 2 Department of Geology, University of Southern California, Los Angeles, CA 90007 (Received 13 April 1987; accepted 16 August 1988)

A downhole magnetic logging tool for the Ocean Drilling Program

In October 1986 the Ocean Drilling Program (ODP) program of the National Science Foundation funded the University of Washington (UW), Seattle, to construct, test, and initially deploy a downhole magnetometer as part of the logging program for the drilling ship JOIDES Resolution. The success of the initial deployment of the magnetometer in a 500‐m gabbroic crustal section during Leg 118 in December 1987 (Leg 118 Scientific Party, 1988), and the general availability of this tool as part of the ODP suite of logging tools, prompted this brief announcement.The UW/ODP magnetic logging tool was designed by IFG Corporation of Toronto, Canada, and underwent several design modifications specifically for ODP use by both URTEC Instrument Sales Limited, of Toronto, and the Borehole Research Group (BRG) at Lamont‐Doherty Geological Observatory (LDGO), Palisades, N.Y. The tool consists of three orthogonally oriented ring core fluxgate magnetometers, a susceptibility sensor, and two thermocouples which monitor the internal temperature of the probe. The fluxgate magnetometers each have a range of +/−100,000 n T and a sensitivity of 0.1 nT. The fluxgates have been calibrated in magnetic fields ranging from 3000 to 100,000 n T and at a range of temperatures between 25° and 90°C. The susceptibility coil has a sensitivity of approximately 10∼5 SI units when run in a borehole 10″ (25 cm) in diameter. In addition to magnetic susceptibility, the coil measures electrical resistivity, but with this particular type of sensor, the measurement is only useful in formations with very high electrical conductivities. The entire magnetometer syst em is currently capable of being run at operating temperatures up to 125°C without damage. Although the fluxgate magnetometer output remains linear within this range, the susceptibility probe becomes nonlinear and exhibits some thermal hysteresis at elevated temperatures. T h e susceptibility probe will require more detailed calibration in order to utilize measurements made at these higher (>60°C) temperatures. Although the magnetometer probe does not currently have an independent system for azimuthal orientation in highly magnetic media (e.g., accelerometers or a gyroscope), this is a desirable feature which is hoped to eventually be included in the magnetic logging package.

Reconnaissance de structures tectoniques et volcaniques sous-marines de l'arc recent des Petites Antilles (Kick'em Jenny, Qualibou, Montagne Pelee, nordouest de la Guadeloupe)

A multibeam bathymetric survey (SEACARIB 1) was carried out in April 1985, on board the R.V. Conrad (Lamont-Doherty Geological Observatory) off the western coasts of several islands of the Lesser Antilles, complementing a previous survey of the same type (ARCANTE 2-THERMOSITE, 1980) devoted to adjoining areas in Guadeloupe, Martinique and St. Lucia. It allowed us to precisely map submarine volcanoes in a marginal setting behind the recent arc, the main volcanic axis of the archipelago, emplaced during the Neogene. The Kick'em Jenny volcano (south of the Grenadines) is the only active submarine volcano of the Lesser Antilles. It is a small and very young cone (probably only tens or hundreds of years old) which was hydrothermally active during the survey. The Directeur volcano (Guadeloupe) is the largest submerged volcanic centre thus far detected in the Lesser Antilles having been formed between 3.3 and 2.9 Ma. During the 1980 survey, two other large volcanoes were discovered: off southern Basse-Terre, Guadeloupe (Vieux Fort volcano, 2.5–2.0 Ma) and in front of Fort de France Bay, Martinique (Schoelcher volcano, older than 4.2 Ma). Several other much smaller volcanoes have been mapped off the same coasts, particularly the Bouillante seapeaks (Guadeloupe).Moreover, large tectonic structures cut the recent arc transversally and obliquely. The well-known Qualibou depression, on the island of St. Lucia, was interpreted in various ways; neither the hypothesis of a large caldera, the western side of which collapsed offshore, nor the suggestion of a huge rotational gravity slide, are confirmed. The depression seems more likely to have been controlled by tectonic factors shaping a complex graben structure. The seaward extension appears to be restricted to a northern channel, the Soufrière Channel. The St. Pierre fault, in Martinique, is a large transverse feature, extending seaward down to some 2000 m depth. To the south, it bounds the Mount Pelée active volcanic system, and the escarpment of the fault forms a “dam” against subaqueous pyroclastic flows running down from the volcano. These flows are responsible for the unusually smooth morphology of the submarine flanks. The Zombi fault of northwest Guadeloupe is part of a first-order feature, extending along at least 130 km, from Montserrat in the north, to Marie-Galante in the east. This curved fracture cuts across the northern central part of the Lesser Antilles, passing progressively from a subparallel to a transverse orientation with respect to the axis of the island arc.These types of surveys are important, because they provide better understanding of the structure and recent geological evolution of the recent volcanic arc. They are also a useful complementary tool for geothermal and seismological studies.

William L. Donn 1918–1987

William L. Donn, Professor Emeritus of the Department of Earth and Planetary Sciences, City College of New York, and Special Research Scientist at Lamont‐Doherty Geological Observatory (LDGO) of Columbia University (Palisades, N.Y.), died at his home on June 30, 1987, at the age of 69. Bill demonstrated expertise in a wide range of fields, with a highly productive and creative research and writing career that included geology, oceanography, climatology, atmospheric physics, and meteorology.Donn was born in Brooklyn, N.Y., on March 2, 1918. At the tender age of 10 years, he demonstrated his love and talent for science by building a telescope with his brother, Bertram. During his undergraduate years at Brooklyn College, he switched his major from astronomy to geology. He was largely selftrained in both meteorology and oceanography, serving as head of the Meteorology Section, U.S. Merchant Marine Academy during World War II . One by‐product of these years was the textbook Meteorology—With Marine Applications, first published in 1946. This widely adopted text became a standard for a generation of mariners and college students.

Best Student Papers for 1987 Spring Meeting

As they did at previous national meetings, several AGU sections selected Best Student Papers at the 1987 Spring Meeting in Baltimore, Md., during May 1987 as a means of encouraging student participation.Pal Wessel was selected by the Geodesy Section to receive their Best Student Paper Award for his paper entitled “Global Gravity Crossover Corrections: Implications and Applications,” which was coauthored by A. B. Watts (Lamont‐Doherty Geological Observatory (LDGO), Palisades, N.Y.). Wessel received his B.Sc. (1982) and M.S. (1984) from the University of Oslo, Norway, in applied geophysics, while working on inversion of gravity anomalies over a continental rift (Oslo Graben). He is currently a Ph.D. candidate at LDGO. Wessel's research in gravity includes statistical analysis of shipboard gravity data, gridding algorithms, and computation of gravimetric geoids. He is also working on flexre of young oceanic lithosphere caused by thermal stresses.

A new airgun array for Conrad

The research vessel Robert D. Conrad, owned by the U.S. Navy and operated by Lamont‐Doherty Geological Observatory (LDGO) of Columbia University (Palisades, N.Y.), is a multi‐use ship that is principally employed for marine geology and geophysics surveys. For the last 10 years, the Conrad has had a multichannel seismic (MCS) capability, which is used to determine deep structure and velocity of the suboceanic crust around the world. While it is expected that the Conrad will be replaced by a new vessel sometime in the 1990s, the needs of current and future projects required that her MCS capability be upgraded and enhanced now. The National Oceanic Reflection Profiling Organization (NORPO) recommended in 1985 that up to $2 million be invested in the immediate upgrading of the MCS capability of the U.S. academic research fleet (see “Marine Multichannel Seismology Workshop ” in Eos, February 11, 1986, p. 70). This recommendation bore first fruit in late 1985, when The National Science Foundation (NSF) granted $425,000, matched by $ 100, 000 in Lamont‐Doherty institutional funds, for an upgrade to the seismic source system on the Conrad.

Radiolaria: Opal Artisans in the Sea

0. Roger Anderson 0. Roger Anderson, professor of Natural Sciences at Columbia Univ. Teachers College and Senior research scientist, Biological Oceanography, Lamont-Doherty Geological Observatory of Columbia Univ., Pallisades, NY 10964. Anderson attended Washington University in St. Louis, Missouri, earning his Bachelors degree (1959), Masters (1961) and Doctorate (1964) in Biology and Education. Appointed at Columbia Univ. in 1964, he has served as educational consultant in biology and is a member of the editorial advisory board of Marine Microbial Food Webs (Villefranche) and The Journal of Foraminiferal Research. During 1976-77 he was president of The National Association for Research in Science Teaching. Anderson has been a visiting research biologist at major biological laboratories throughout the world. He has published numerous articles on topics in marine biology, cell biology of protozoa, and the teaching of biology. He is coeditor of a book on Cytomechanics (Springer-Verlag, Heidelberg), and the author of four books, including his most recent one on Radiolaria (1983) (Springer-Verlag, NY).

Supernovae: Little Bear's mass loss rate

Supernovae: Little Bear's mass loss rate

Geophysicists as parents

About 30 people attended an evening panel session on combining career and family during the 1985 AGU Spring Meeting in Baltimore, Md. The panel, sponsored by the Education and Human Resources Committee, was moderated by Constance Sancetta (Lamont‐Doherty Geological Observatory (LDGO) of Columbia University, Palisades, N.Y.) and consisted of Claire Davidson (U.S. Geological Survey (USGS), Reston, Va.), M. Grant Gross (Ocean Sciences, National Science Foundation (NSF), Washington, D.C. ) , and Joseph J. Morley (LDGO). Each panelist was asked to describe his or her experiences and the lessons that he or she learned from them.

Problems of structural correlation in accretionary prisms. : I. W. D. Dalziel, Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964, U.S.A.

Problems of structural correlation in accretionary prisms. : I. W. D. Dalziel, Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964, U.S.A.