Adam Maloof - Publications
Chronological -- Topical
True Polar Wander
Maloof, A.C., Halverson, G.P., Kirschvink, J.L., Schrag, D.P., Weiss, B.P., and Hoffman, P.F. 2006, Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard; Geological Society of America Bulletin, 118 pp. 1099-1124. DOI: 10.1130/B25892.1 [pdf]
Halverson, G.P., Maloof, A.C., Schrag, D.P., Dudas, F.O., and Hurtgen, M.T. 2007, Stratigraphy and geochemistry of an 800 Ma negative carbon isotope stage in northeast Svalbard; Chemical Geology, 237 pp. 5-27. DOI: 10.1016/j.chemgeo.2006.06.013 [pdf]
Halverson, G.P., Dudas, F.O., Maloof, A.C. and Bowring, S.A. 2007, Evolution of the 87Sr/86Sr composition of Neoproterozoic seawater; Palaeogeography, Palaeoclimatology, Palaeoecology, 256 pp. 103-129 DOI:10.1016/j.palaeo.2007.02.028 [pdf]
Halverson, G.P., Hoffman, P.F., Schrag, D.P., Maloof, A.C., and Rice, A.H.N. 2005, Toward a Neoproterozoic composite carbon-isotope record; Geological Society of America Bulletin 117 pp. 1181-1207. DOI: 10.1130/B25630.1 [pdf]
Swanson-Hysell, N.L, Maloof, A.C., Halverson, G.P., and Hurtgen, M.T., Covariation in the carbon isotopes of carbonate and organic carbon across the Neoproterozoic Bitter Springs Stage - No pre-Sturtian Rothman Ocean, in prep .(AGU Fall 2008).
Hurtgen, M.T., Halverson, G.P., Swanson-Hysell, N.L. and Maloof, A.C., Early Neoproterozoic Sulfur Isotopes and the Rise (and Fall) of Oxygen, in prep. (AGU Fall 2008).
Jones, D.S., Maloof, A.C., Hurtgen, M.T., Rainbird, R.H. and Schrag, D.P., Regional and global chemostratigraphic correlation of the Early Neoproterozoic Shaler Supergroup, Arctic Canada, Precambrian Research, in prep.
Swanson-Hysell, N.L, Maloof, A.C., Halverson, G.P., and Hurtgen, M.T., Combined paleomagnetic, isotopic and stratigraphyic evidence for true polar wander from the Neoproterozoic Bitter Springs Formation, Central Australia, in prep.
Snowball Earth Glaciation
The snowball Earth hypothesis was developed to explain the juxtaposition of equatorial glacial sediments deposited at sea level and associated chemical sediments that may indicate long term isolation of the ocean from the atmosphere. However, a global carapace of thick sea ice may not be compatible with observations of (A) thick interbedded glacial and non-glacial deposits perhaps indicative of advancing and retreating temperate glaciers fed by a vigorous hydrological cycle, and (B) the survival of a diversity of eukaryotic lineages, including multicellular life, perhaps requiring open seas rather than just isolated refugia around cracks and volcanic islands. Our work is testing the snowball Earth hypothesis by mapping out basin-scale 3D glacial landscapes and the physical- and chemo-stratigraphic architecture of the pre-, syn- and post-glacial record.
Rose, C.V. and Maloof, A.C., The thermal regime of equatorial glaciers and the state of sea ice
cover, Marinoan glaciation, South Australia, in prep.
Rose, C.V. and Maloof, A.C. (2010), Testing models for post-glacial `cap dolostone' deposition: Nuccaleena Formation, South Australia, Earth and Planetary Science letters, in review. []
Halverson, G.P., Maloof, A.C., Hoffman, P.F. 2004, The Marinoan glaciation (Neoproterozoic) in northeast Svalbard, Basin Research 16 pp. 297-324. DOI: 10.1111/j.1365-2117.2004.00234.x [pdf]
Halverson, G.P., Hoffman, P.F., Schrag, D.P., Maloof, A.C., and Rice, A.H.N. 2005, Toward a Neoproterozoic composite carbon-isotope record; Geological Society of America Bulletin 117 pp. 1181-1207. DOI: 10.1130/B25630.1 [pdf]
Hoffman, P.F. and Maloof, A.C. 2003, Comment on: A complex microbiota from snowball Earth times: Microfossils from the Neoproterozoic Kingston Peak Formation, Death Valley, USA, by Corsetti, F.A., Awramik, S.M., and Pierce, D., Proceedings of the National Academy of Sciences 100 pp. 4399-4404. [pdf]
Maloof, A.C., Kellogg, J.B., and Anders, A.M. 2002, Neoproterozoic sand wedges: crack formation in frozen soils under diurnal forcing during a snowball Earth; Earth and Planetary Science Letters 204 pp. 1-15.DOI:10.1016/S0012-821X(02)00960-3 [pdf]
Hoffman, P.F. and Maloof, A.C. 2001, Tilting at Snowballs, A comment on Proterozoic equatorial glaciation: Has 'snowball Earth' a snowball's chance?, by Williams, G.E. and Schmidt, P.W., The Australian Geologist 117 pp. 21-25, 2000. [pdf]
Maloof, A.C. 2000, Superposed folding at the junction of the inland and coastal belts, Damaran orogen, NW Namibia; Communications of the Geological Survey of Namibia, Henno Martin Commemorative Volume 12 pp. 89-98. [pdf]
Hoffman, P.F. and Maloof, A.C. 1999, The Snowball theory still holds water; Nature 397 p. 384. DOI: 10.1038/17006 [pdf]
Non-Dipole contributions to the Geomagnetic Field
Central to all paleomagnetic studies is the Geocentric Axial Dipole Hypothesis, which states that, throughout Earth history, when averaged over 10,000 years or more, Earth’s magnetic field can be closely approximated by a dipole magnet aligned with the spin axis (i.e., geographic north). However, today there is a persistent 4% quadrupolar component to the field, and in the past, larger nondipole fields may have affected our paleomagnetic records of paleogeography and the supercontinent cycle. 1.1 billion year old lavas from a failed rift in Ontario, Canada reportedly contain at least three asymmetric magnetic reversals that may indicate an ancient 20% quadrupole and necessary reassessment of Rodinian Paleogeography.
Swanson-Hysell, N.L., Maloof, A.C., Weiss, B.P. and Evans, D.A.D. 2009, No asymmetry in geomagnetic reversals recorded by 1.1-billion-year-old Keweenawan basalts, Nature Geoscience, 2 pp. 713-717. DOI: 10.1038/NGEO622 [pdf]
Cambrian Radiation of Animals
By 1859, Darwin had recognized the sudden appearance of animal fossils in the geologic record, after more than three billion years with just bacteria and algae, as the most significant challenge to his hypothesis for the origin of species. Since Darwin, scientists have recognized animal fossils much older than trilobites. Ediacaran animals resembling jelly fish and sea pens appear at least 575 million years ago, and lipid biomarker and molecular phyologenetic studies indicate an even more ancient record back to 635 Ma for some animals like sponges. We are using the sedimentary rock record to detect and study coincident changes in ocean chemistry and sea level that may have caused or been caused by the radiation of animals between 550 and 510 million years ago.
Maloof, A.C., Dudas, F.O. and Bowring, S.A., 87Sr/86Sr variability during the transition from Ediacaran to late Early Cambrian times, in prep.
Maloof, A.C., Ramezani, J., Bowring, S.A., Fike, D.A., Porter, S.M. and Mazouad, M. (2010), Timing and duration of the Nemakit-Daldynian--Tommotian boundary d13C shift, Morocco, Geology, in review. []
Maloof, A.C., Schrag, D.P., Crowley, J.L., and Bowring, S.A. 2005, An expanded record of Early Cambrian carbon cycling from the Anti-Atlas Margin, Morocco; Canadian Journal of Earth Sciences, 42 pp. 2195-2216. DOI: 10.1139/E05-062 [pdf]
Most of the martian and lunar surface is made of basalt. Scientists would like to use the geometry of craters and ejecta blankets and patterns of crustal magnetization on Mars and the Moon to infer properties of Martian and Lunar crust, such as rheology, ice content, and mineralogy. By studying the only young crater on Earth that is preserved entirely in basalt, we have answered questions about the conditions necessary to generate rampart ejecta patterns and shock demagnetization.
Maloof, A.C., Stewart, S.T., Weiss, B.P., Soule, S.A., Swanson-Hysell, N.L., Louzada, K.L., Garrick-Bethell, I. and Poussart, P.M. 2009, Geology of Lonar Crater, Geological Society of America Bulletin, in press. [pdf]
Louzada, K.L., Weiss, B.P., Maloof, A.C., Stewart, S.T., Swanson-Hysell, 2008, Paleomagnetism of Lonar Impact Crater, India, Earth and Planetary Science Letters, 275 pp. 208-319. [pdf]
Fe-Cycling, Paleomagnetism and Stratigraphic Architecture of Holocene Platformal Carbonates
Virtually all of our pre-Mesozoic records of Earth history and climate change are derived from shallow water carbonates deposited on continental shelves. However, we know surprisingly little about how modern analogue sedimentary environments to these rocks record global change. By studying Holocene muds from the Bahamas, we have documented the origin and preservation of sedimentary magnetite and the stratal architecture controlled by the interplay of tidal channel processes and Holocene sea level rise.
Maloof, A.C. and Grotzinger, J.P. Migration rates of tidal channels on a Modern carbonate platform and the origin of upward shallowing parasequences, Triple Goose Creek, Andros Island, Bahamas, in prep. (AGU Fall 2008).
Maloof, A.C., Kopp, R.E., Grotzinger, J.P., Fike, D.A., Bosak, T., Vali, H., Poussart, P.M., Weiss, B.P. and Kirschvink, J.L. 2007, Sedimentary iron cycling and the origin and preservation of magnetization in platform carbonate muds, Andros Island, Bahamas; Earth and Planetary Science Letters, 259 pp.581-598. DOI: 10.1016/j.epsl.2007.05.021 [pdf]
Kopp, R.E., Weiss, B.P., Maloof, A.C., Vali, H., Nash, C.Z., and Kirschvink, J.L. 2006, Chains, clumps, and strings: Magnetofossil taphonomy with ferromagnetic resonance spectroscopy; Earth and Planetary Science Letters, 247 pp. 10-25. DOI: 10.1016/j.epsl.2006.05.001 [pdf]
Testing Milankovitch Theory in Cenozoic Sediments
The standard way to develop an age model for a column of sediment is to tune isotopic or lithological data to an astronomical timescale, and then to check to see that spectral power in the tuned signal is significant with respect to background red-noise at the expected frequencies. However, this technique does not account for the spectral power that tuning injects into pure red noise. Calculating confidence intervals for tuned red noise allows for more accurate determination of significance in tuned isotopic data.
Proistosescu, C., Huybers, P. and Maloof, A.C., An objective statistical test for eccentricity forcing of Oligo-Miocene climate, in prep. (AGU Fall 2008)
Last Ingerglacial Global Sea Level
Though its warmth (polar temperatures ~3-5°C warmer than today) was caused partly by variations in Earths obliquity, the Last Interglacial (LIG) stage (ca. 130,000 - 115,000 years ago ) serves as a partial analog for low-end future warming scenarios. Multiple indicators suggest LIG global sea level was higher than at present; based upon a small set of local sea level indicators, the IPCC Fourth Assessment Report inferred an elevation of ~4-6 meters. However, sea level is often mistakenly viewed as a simple function of changing global ice volume. This viewpoint neglects local variability, which arises from several factors, including the distortion of the geoid and the elastic and isostatic effects of lithospheric deformation by shifting ice masses. Therefore, we are attempting to generate an accurate reconstruction of past global and local sea levels during the LIG that integrates globally-extensive data sets of sea level indicators. We hope that this work will test the robustness of the IPCCs global estimate of future sea level change.
Kopp, R.E., Simons, F.J., Mitrovica, J.X., Maloof, A.C., Oppenheimer, M. (2009), Probabilistic assessment of sea level during the Last Interglacial, Nature, in press. []
