Division of Geological and Planetary Sciences.
Science progresses by a process called hypothesis testing, which involves proposing an idea and then subjecting it to experimental tests. However, someone has to initially propose scientifically plausible hypotheses for this process to work. Prof. Kirschvink has originated several such ideas aimed at increasing our understanding of how biological evolution has influenced, and has been influenced by, major events on the surface of the Earth. In more-or-less chronological order, the major contributions include:
Prof. Kirschvink delivered the Carl Sagan Memorial Lecture at the 2001 American Geophysical Union Fall meeting in San Francisco, a webcast of which is posted on the AGU www site. Click here for the current location of Asteriod 27711 Kirschvink, a member of the Phocaea family with an unusually high eccentricity, orbiting between Mars and Jupiter, with a magnitude of 15, about 3 km in diameter.
Joe is also the real Iron Man!. Additional contributions include various studies in rock- and paleomagnetism and Biomagnetism, and those from recent or current students: Prof. Robert Ripperdan, Prof. David A. Evans, Dr. John Holt, Prof. Benjamin Weiss, Prof. Robert Kopp.
The Caltech Paleomagnetics Laboratory has two 2G Enterprises pass-through SQuID magnetometers (one retrofitted from a two-axis Superconducting Technology, Inc.) to measure three-axis magnetic moments with background noise sensitivity of 10-12 Am2 per axis. Currently, both magnetometers are operating in vertical mode, but one can swivel to operate in either horizontal or vertical mode. Both magnetometers have an RAPID automatic sample changer that can hold between 100-120 samples and can measure ~1 sample per minute including axis rotations (5 measurements total, Kirschvink et al. 2008). One is a snake-chain model, the other is the newer xy table model both designed by Professor Kirschvink. The quartz sample holder systems on both instruments reduce holder noise to 10-10 emu levels allowing measurement of weakly magnetized samples. These magnetometers are housed in two separate shielded rooms: 1) a 8 m3 two-layer mu-metal shield with residual fields ranging from 100 to less than 5 nT and 2) a 9 m x 3 m x 3 m room Gary Scott room made with transformer steel with residual magnetic fields of < 200 mT. Within each shielded room is a magnetically shielded ASC furnace, permitting up to 100 paleomagnetic specimens to be thermally demagnetized at once with a cycle time of > 1 hour using automated controlling software with optional controlled nitrogen atmosphere to prevent oxidation during heating.
The larger shielded room in Caltech’s Paleomagnetics Laboratory also houses an Ultra-High Resolution Scanning SQuID Microscope, developed in the Kirschvink Laboratory, can map the vertical component of the magnetic field above room temperature samples using an automated xy nanostage. Housed in an additional 4 layers of mu-metal shields, it has a sensitivity of 10-16 Am2 and a spatial resolution down to 40 μm. Although utilized for rock magnetic applications as well, through software and procedures developed with collaborators at MIT and Harvard, the magnetic moment can be calculated from very weak magnetic samples to address paleomagnetic questions.
Both of the 2G Enterprises SQuID magnetometers have an integrated in-line computer-controlled pulse magnetizer, an ARM acquisition system, and the 2G/Applied Physics alternating field demagnetization unit. The total setup thereby allows fully automated rock magnetic measurements to be made such as AF demagnetization, IRM acquisition and demagnetization (AF), ARM acquisition and demagnetization, rotational remanent magnetization (RRM) and demagnetization, and backfield IRM acquisition and demagnetization. User inputs for number of steps can change sample measurement time, but a complete IRM acquisition and AF demagnetization cycle of 30 measurements takes ~30 minutes. Plotting and analysis of rock magnetic experiments is performed using the RAPID MatlabTM scripts. In-line susceptibility bridges also allow susceptibility measurements to be made on each sample run using the magnetometers. For more detailed susceptibility measurements, the laboratory has an AGICO MFK1-FA KappaBridge with rotator, cryostat and furnace attachments for partially automated measurements of anisotropy of magnetic susceptibility and fully automated low-temperature and high-temperature susceptibility measurements. Other supplies and equipment in Professor Kirschvink's paleomagnetics lab include liquid nitrogen for low-temperature cycling, hall probes, portable fluxgates, and pass-through susceptibility bridges.
The 9m x 3m x 3m shielded room is an epoxy-sealed dust and particle-free clean laboratory maintained under positive pressure with a deionized water shower entryway and includes distilled-water sink. This allows magnetic measurements of weak biological samples on the 2G SQuID magnetometer as well as the Ultra-High Resolution Scanning SQuID Microscope. The laboratory also has a fume hood and an optical microscope to help biological analyses and experiments. Recent study of human magnetoreception has been done in a separate 8 m3 metal room with built-in coils to produce directed magnetic fields through automated software protocols.
The controlling hardware and software for the 2G SQuID magnetometer is currently being upgraded to improve the system's performance, flexibility, and user interface. The next generation of controlling software will be moved from Visual Basic to C#. Work is being done on the hardware and software of the magnetically shielded ASC furnace to add additional thermocouples for extra precision in thermal measurements. Lastly, the lab has experimented in using gallium in the cryocooler system of the 2G SQuID magnetometers to allow more efficient cooling and reduce liquid helium consumption (e.g. Kirschvink, GP13A-1380 abstract, AGU Fall Meeting 2015).
Simons Postdoctoral Fellow
Peer-Reviewed Publications & Books, 1991+: Google scholar lists the most popular articles, and citation stats.
|1||2016c. Kobayashi, A., Golash, H.N., and J.L. Kirschvink, A First Test of the Hypothesis of Biogenic Magnetite-Based Heterogeneous Ice-Crystal Nucleation in Cryopreservation. Cryobiology Vol. 72, 216-224. doi:10.1016/j.cryobiol.2016.04.003|
|2||2016b. Slotznick, S.P., Winston, D., Webb, S.W., Kirschvink, J.L., and Fischer, W.W. Iron mineralogy and redox conditions during deposition of the mid-Proterozoic Appekunny Formation, Belt Supergroup, Glacier National Park. in: MacLean, J.S., and Sears, J.W., eds., Belt Basin: Window to Mesoproterozoic Earth: Geological Society of America Special Paper 522, p. , doi:10.1130/2016.2522(09).|
|3||2016a. Ward, L.M., J.L. Kirschvink, & W.W. Fischer. Timescales of Oxygenation Following the Evolution of Oxygenic Photosynthesis. Origins of Life and Evolution of Biospheres, March 2016, Volume 46 (1), pp 51-65. DOI 10.1007/s11084-015-9460-3|
|4||2015g. Ross N. Mitchell, Timothy D. Raub, Samuel C. Silva, & Joseph L. Kirschvink. Was the Cambrian explosion both an effect and an artifact of true polar wander? American J. Science, Vol. 315, December, 2015, P. 945-957, DOI 10.2475/10.2015.02|
|5||2015f. Benjamin P. Weiss, Adam C. Maloof, Nicholas Tailby, Jahandar Ramezani, Roger R. Fu, Veronica Hanus, Dustin Trail, E. Bruce Watson, T. Mark Harrison, Samuel A. Bowring, Joseph L. Kirschvink, Nicholas L. Swanson-Hysell, & Robert S. Coe, Pervasive Remagnetization of Detrital Zircon Host Rocks in the Jack Hills, Western Australia and Implications for Records of the Early Geodynamo. Earth and Planetary Science Letters, 430, 115-128 (DOI.org/10.1016/j.epsl.2015.07.067).|
|6||2015e. Sarah P. Slotznick, Jerry Zieg, Samuel M. Webb, Joseph L. Kirschvink, and Woodward W. Fischer, Iron Mineralogy and Redox Chemistry of the Mesoproterozoic Newland Formation in the Helena Embayment, Belt Supergroup, Montana. Northwest Geology, v. 44, 2015, p. 55-72 (2015).|
|7||2015d. Kirschivnk, J.L., The Accidental Discovery of a Chemotactic Override on the Swimming Direction of Magnetotactic Bacteria (an Amusing Story). Japan Geoscience Letters v. 11, special, (2015).|
|8||2015c. Jeroen Hansma, Eric Tohver, Maodu Yan, Kate Trinajstic, Brett Roelofs, Sarah Peek, Sarah P. Slotznick, Joseph L. Kirschvink, Ted Playton, Peter Haines, & Roger Hocking. Late Devonian carbonate magnetostratigraphy from the Oscar and Horse Spring Ranges, Lennard Shelf, Canning Basin, Western Australia. Earth and Planetary Science Letters 409 (2015) 232-242. Supplemental data here.|
|9||2015b. Kirschvink, J.L., Yukio Isozaki, Hideotoshi Shibuya, Yo-ichiro Otofuji, Timothy D. Raub, Isaac A. Hilburn, Teruhisa Kasuya, Masahiko Yokoyama, & Magali Bonifacie. Challenging the sensitivity limits of Paleomagnetism: Magnetostratigraphy of weakly magnetized Guadalupian-Lopingian (Permian) Limestone from Kyushu, Japan. Palaeogeography, Palaeoclimatology, Palaeoecology 418 (2015) 75-89. Stats spreadsheet here.|
|10||2015a. Ward, P.D. and Kirschvink, J.L. A New History of Life: The radical new discoveries about the origins and evolution of life on Earth. Bloomsbury Press, N.Y. (391 pp). ISBN: 9781608199075|
|11||2014b. Kirschvink, J.L. Sensory Biology: Radiowaves zap the biomagnetic compass. Nature (2014), doi:10.1038/nature13334, published online 07 May 2014.|
|12||2014a. Fisher, W.W., Fike, D.A., Johnson, J.E., Raub, T.D., Guan, Y., Kirschvink, J.L., Eiler, J.M. SQUID-SIMS, a useful approach to uncover primary signals in the Archean sulfur cycle Proc. Natl. Acad. Sciences 111(15), 5468-5473 www.pnas.org/cgi/doi/10.1073/pnas.1322577111. See also: A new Tool for unscrambling the rock record.|
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