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Update from Classifying the Unknown: the Lunar Edition

January 10th, 2016

9[Guest Blogger: Annette Hilton (’17)]

This past summer I had the privilege of working as an intern in the Earth and Planetary Sciences department at the American Museum of Natural History (AMNH) — please see my previous blog post. Since then I’ve been lucky enough to continue research with my advisor, Dr. Juliane Gross (Rutgers University, associate of AMNH).

Our project was to investigate a new meteorite found in Northwest Africa in 2015 to: 1) confirm its lunar origin and potential grouping, 2) classify the rock, 3) place constraints on its crystallization history and source location, and 4) improve our understanding of unsampled areas of the Moon and expand our knowledge of lunar highland rock types.

During our research we conducted Electron Probe Micro-Analysis (EPMA) at the AMNH and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) at the Lamont-Doherty Earth Observatory (LDEO) of Columbia University to obtain geochemical data. We additionally calculated modal mineralogy using qualitative elemental X-ray maps in combination with two computational programs called IDRISI Selva (Eastman, 2012; Fisher, 1936) and XMapTools (MATlab) (Lanari et al., 2013). Using this data set in conjunction with a computational program (Calzada-Diaz et al., 2015), we were able to estimate a few potential source locations on the lunar surface from which the meteorite might have originated.

The name and classification for the meteorite was accepted by the Meteoritical Society in late December 2015. Its official name is Northwest Africa 10401 and is one of 60 approved meteorites classified as lunar. We classified the petrography of the rock as an anorthositic troctolite with a granulitic texture, which means it contains mainly plagioclase with a mafic component (i.e., olivine and pyroxene) that has a granular (rounded) texture. Composition of the rock was based on our 6 x12mm thick section of the sample and is composed primarily of Ca-bearing plagioclase (59-65%), with lesser olivine (23-26%), pyroxene (12-15%) (orthopyroxene and clinopyroxene), glass, and accessory phases spinel and metal.

We submitted an abstract to the 47th Lunar and Planetary Sciences Conference in March 2016, at which Juliane Gross and I will present our research about this meteorite Northwest Africa 1040.
Annette010716Fig. 1: Mosaic X-ray elemental maps of the meteorite thick section. a) Si Kα map b) Ca Kα map d) combined RedGreenBlue (RGB-SiFeCa)) map. In general, blue-green = olivine; blue = orthopyroxene; light pink = clinopyroxene; pink = maskelynite (shocked plagioclase); white = epoxy (Hilton et al., 2016).

The meteoritical bulletin classification can be found at: http://www.lpi.usra.edu/meteor/metbull.php?code=62636

Acknowledgements: A big thank you to Juliane Gross, AMNH, NSF REU Program for Physical Sciences, Abigail Calzada-Diaz for running the computational program for the lunar surface, and Wooster’s excellent Geology professors and staff.

[College news release. January 11, 2016]

References:

Calzada-Diaz, A., Joy, K.H., Crawford, I.A., and Nordheim, T.A. 2015. Constraining the source regions of lunar meteorites using orbital geochemical data. Meteoritics & Planetary Science 50: 214–228.

Eastman, J.R., 2012. IDRISI Selva. Clark University, Worcester, MA.

Fisher, R.A. 1936. The use of multiple measurements in taxonomic problems. Annals of Eugenics 7: 179-188.

Hilton, A., Gross, J., Korotev, R., Calzada-Diaz, A. 2016. Classifying the unknown–the lunar edition: North West Africa 10401 a new type of the Mg-suite rock?  47th Lunar and Planetary Science Conference. Abstract.

Lanari, P., et al. 2013.  XMapTools: A MATLAB©-based program for electron microprobe X-ray image processing and geothermobarometry. Computers & Geosciences, http://dx.doi.org/10.1016/j.cageo.2013.08.010

Science Highlights from VMSG 2016

January 8th, 2016

Dublin, Ireland – The technical program of VMSG 2016 concluded today and I am saturated with new ideas about igneous systems. Abstracts for all of the talks and posters can be found on the VMSG 2016 website.  There were so many excellent presentations, but I thought I’d mention just a few of the highlights.

Ian Saginor at Keystone College shared his xxxx initiative to use 3-D models for volcanology education and outreach.

Ian Saginor  shared his Volcano Terrain Initiative to use 3-D models for volcanology education and outreach.

 

Maren Kahl used a clever systems approach to understand the magmatic plumbing system at Mt. Etna. She combined kinetic and thermodynamic modeling of complexly zoned olivine crystals erupted over time. (Link to her 2015 Journal of Petrology paper)

 
When Ben Hayes discussed his idea for the formation of plagioclase-pyroxene layering in the Bushveld Complex by downward percolation of a dense melt through a crystal mush, Mary Reinthal (’16) said she felt like she was reliving Petrology class. I guess that layered mafic intrusions lab had an impact!

 
Janine Kavanagh presented her experimental work on dikes in which she observed hybrid sill-dike intrusions when her injected fluids impinged on boundaries between layers in the host rock. (Link to her 2015 Earth and Planetary Science Letters paper)

 
John Maclennan gave a talk about the uncertainties (and deadly implications) of interpreting pressures from CO2 compositions of melt inclusions.

 
Chris Bean explained that, by recording long period (Lp) seismic events close to the source, we can see that they are better explained by brittle failure events in shallow edifice rocks rather than magma movement. (Link to his 2014 Nature paper)

 
Many presenters referred to the recent Nature paper by 2015 by Bergantz, Schleicher, and Burgisser on magma mush dynamics. Their study related magma injection rate to complex mineral textures and fabrics in magmatic systems. (Link to Bergantz et al., 2015 Nature paper)

Wooster’s Fossils of the Week: Atrypid brachiopods attached to a trepostome bryozoan from the Upper Ordovician of southern Indiana

January 8th, 2016

Zygospira Attached 585This is a follow-up post to our entry on Christmas Day two weeks ago. Above is a trepostome bryozoan (the long porous piece) with specimens of the atrypid brachiopod Zygospira modesta clustered around it. They are positioned with their ventral valves outward because in life they were attached to this bryozoan with tiny fleshy stalks called pedicles. They were buried quickly enough that this spatial relationship was preserved. Cool. This assemblage was found in the Liberty Formation (Upper Ordovician) exposed in a roadcut in southern Indiana.
Zygospira modesta dorsal annotatedThis is a view of the dorsal side of Zygospira modesta showing the pedicle opening in the ventral valve at the apex of the shell.

References:

Copper, P. 1977. Zygospira and some related Ordovician and Silurian atrypoid brachiopods. Palaeontology 20: 295-335.

Sandy, M.R. 1996. Oldest record of peduncular attachment of brachiopods to crinoid stems, Upper Ordovician, Ohio, USA (Brachiopoda; Atrypida: Echinodermata; Crinoidea). Journal of Paleontology 70: 532-534.

Good things happen at VMSG

January 7th, 2016

Dublin, Ireland – Congratulations to Mary Reinthal (’16) for a successful poster presentation at VMSG 2016!

image-5-768x1024_sizedMary did a fantastic job giving her ‘lightning talk,’ a two-minute round-robin-style presentation of her poster.

The poster session was everything that it should be. Mary received excellent feedback and advice on her research, met a number of people who are working on similar projects, and expanded her post-graduation career opportunities. She was an excellent representative of the Wooster Geology program. Well done!

Wooster Geologists in Ireland

January 6th, 2016

Greetings from Dublin! Mary Reinthal (’16) and I are attending the annual conference of the Volcano and Magmatic Studies Group (#VMSG2016) at Trinity College. Volcanologists, petrologists, geochemists, and geophysicists have gathered to share their research on igneous topics ranging from large igneous provinces (LIPs) to volcanic hazards. We started the conference, appropriately, with a tour of the architecture and building stones on Trinity’s campus.

The tour began in Parliament Square, so named for the Parliament that supported the construction of the surrounding buildings during the 1700s.

The tour began in Parliament Square, so named for the Parliament that supported the construction of the surrounding buildings during the 1700s.

In the background, you see the Chapel (1787-98), which is composed of the golden brown, granular Leinster granite. The windows are surrounded by Portland Stone, a fossiliferous limestone from Dorset.

The floor of the square is paved with polished glacial cobbles of a variety of lithologies, including limestone and andesite.

The floor of the square is paved with polished glacial cobbles of a variety of lithologies, including limestone and andesite.

Walkways of marble from China were added later to make the square more accessible.

Walkways of gneiss from China were added later to make the square more accessible.

Our last stop was the Museum Building, which houses the Geology and Engineering Departments. The building was recently cleaned in a painstaking effort that lasted ~4 years and involved the removal of gypsum deposits by dental drill and soot by a slow stream of water, but it was worth the effort. The architectural details of the Museum Building are breathtaking. On the exterior, the Portland Stone features intricate and unique carvings of leaves, birds, cats and mice, and other natural objects.

Visitors are greeted with robust pillars of limestone or Connemara marble.

Inside the building, visitors are greeted with robust pillars of limestone or Connemara marble.

Step past the pillars and you'll be awed by a soaring, colorful enameled brick ceiling.

Step past the pillars and you’ll be awed by a soaring, colorful enameled brick ceiling.

The Museum Building was the perfect venue for tonight’s conference ice-breaker, where we were finally able to connect faces to familiar names. Overall, it was a successful introduction to a vibrant and welcoming community of scientists. Tomorrow, Mary becomes an official member of that community when she’ll present her research on water on subglacial volcanics.

 

 

Five-Year Anniversary Edition of Wooster’s Fossil of the Week: A tabulate coral from the Devonian of northwestern Ohio

January 1st, 2016

AuloporaDevonianSilicaShale010211This post of Wooster’s Fossil of the Week marks five years of this feature. If you’re counting, that is 260 entries, with never a week missed. To celebrate, I’m returning to the very first fossil in the series, a beautiful encrusting tabulate coral. The original entry is below, with some updates and added links.

This week’s fossil was collected by Brian Bade of Sullivan, Ohio, and donated to Wooster as part of my hederelloid project.  It is a beautiful specimen of the tabulate coral Aulopora encrusting a brachiopod valve from the Silica Shale (Middle Devonian — about 390 million years old) of northwestern Ohio.  [Update: I now know the species is A. microbuccinata Watkins, 1959.] Auloporid corals are characterized by an encrusting habit, a bifurcating growth pattern, and horn-shaped corallites (individual skeletal containers for the polyps).

What is especially nice about this specimen is that we are looking at a well preserved colony origin.  The corallite marked with the yellow “P” is the protocorallite — the first corallite from which all the others are derived.  You can see that two corallites bud out from the protocorallite 180° from each other.  These two corallites in turn each bud two corallites, but at about 160°.  This pattern continues as the colony develops (a process called astogeny).  The angles of budding begin to vary depending on local obstacles; they never again go below 160°.

The polyps inside the corallites are presumed to have been like other colonial coral polyps.  Each would have had tentacles surrounding a central opening, and all were connecting by soft tissue within the skeleton.  They likely fed on zooplankton in the surrounding seawater.  This type of coral went extinct in the Permian, roughly 260 million years ago.

Again, we thank our amateur geologist friends for such useful donations to the research and educational collections in the Geology Department at Wooster.

Later I began to add information about a notable paleontologist associated with the highlighted fossil. I especially wanted to put a face and brief biography with a name we may often see in our taxonomic pursuits but know little about. We can now add this German gentleman from a previous entry —
August_Goldfuss_1841Aulopora was first described in 1826 by Georg August Goldfuss (1782-1848), a German paleontologist and zoologist. (Goldfuß is the proper spelling, if I can use that fancy Germanic letter.) He earned a PhD from Erlangen in 1804 and later in 1818 assumed a position teaching zoology at the University of Bonn. With Count Georg zu Münster, he wrote Petrefacta Germaniae, an ambitious attempt to catalog all the invertebrate fossils of Germany (but only got through some of the mollusks). The 1841 portrait above is by Adolf Hohneck (1812-1879).

Since the first few entries I began to add a few critical references for the fossils and related stratigraphy. At first these were for me so that I could remember where I got the information used in the text. Later I noted that students and others were finding these entries online and using them as brief introductions to particular taxa. A few references made each entry a starting point for someone else’s paleontological explorations. Here are some added citations for Aulopora

References:

Fenton, M.A. 1937. Species of Aulopora from the Traverse and Hamilton Groups. American Midland Naturalist 18: 115-119.

Fenton, M.A. and Fenton, C.L. 1937. Aulopora: a form-genus of tabulate corals and bryozoans. American Midland Naturalist 18: 109-115.

Goldfuß, G.A. 1826-1844. Petrefacta Germaniae. Tam ea, quae in museo universitatis Regia Borussicae Fridericiae Wilhelmiae Rhenanae servantur, quam alia quaecunque in museis Hoeninghusiano Muensteriano aliisque extant, iconibus et descriptionibus illustrata = Abbildungen und Beschreibungen der Petrefacten Deutschlands und der angränzenden Länder, unter Mitwirkung von Georg Graf zu Münster, Düsseldorf.

Helm, C. 1999. Astogenese von Aulopora cf. enodis Klaamann 1966 (Visby-Mergel, Silur von Gotland). Paläontologische Zeitschrift 73 (3/4): 241–246. [Courtesy of Paul Taylor]

Scrutton, C.T. 1990. Ontogeny and astogeny in Aulopora and its significance, illustrated by a new non‐encrusting species from the Devonian of southwest England. Lethaia 23: 61-75.

Watkins, J.L. 1959. Middle Devonian auloporid corals from the Traverse Group of Michigan. Journal of Paleontology 33: 793-808.

Wooster’s Fossil of the Week: Tiny atrypid brachiopods from the Upper Ordovician of southern Ohio

December 25th, 2015

Zygospira modesta Waynesville 585These exquisite little brachiopods are among the most abundant fossils in the Upper Ordovician of the Cincinnati area. My Invertebrate Paleontology students collected dozens of them from the Waynesville Formation on our field trip to Caesar Creek Lake last semester. Their ubiquity, though, doesn’t make them any less precious.
Zygospira modesta dorsalThis is Zygospira modesta (Say in Hall, 1847). Above is a dorsal valve view of a single specimen. At the apex you can see a tiny round hole from which a fleshy pedicle extended to attach the brachiopod to a hard substrate.
Zygospira modesta ventralHere is the ventral valve view. Zygospira is an atrypid brachiopod, meaning that its internal support (brachidium) for the filter-feeding lophophore is looped in a characteristic way, shown below.
Hall diagram ZygospiraThe diagrams above are from Hall (1867) who named the genus Zygospira and wished to further distinguish it from other atrypid brachiopods.

The taxonomy of Zygospira modesta is a bit messy, as many early 19th Century species descriptions tended to be. It was apparently first named Producta modesta by Thomas Say (see below) but not actually published as such. James Hall described it as Atrypa modesta in 1847. Later in 1862 he named Zygospira as a new genus, making Z. modesta its type species but not indicating a type locality.
Thomas_Say_1818We met Thomas Say (1787-1834) earlier in this blog, recognizing him as the scientist who named Exogyra costata in 1820. He is shown above in an 1818 portrait. Say was a brilliant American natural historian. Among his many accomplishments in his short career, he helped found the Academy of Natural Sciences of Philadelphia in 1812, the oldest natural science research institution and museum in the New World. He is best known for his descriptive entomology in the new United States, becoming one of the country’s best known taxonomists. He was the zoologist on two famous expeditions led by Major Stephen Harriman Long. The first, in 1819-1820, was to the Great Plains and Rocky Mountains; the other (in 1823) was to the headwaters of the Mississippi. Along with his passion for insects, Say also studied mollusk shells, both recent and fossil. He was a bit of an ascetic, moving to the utopian socialist New Harmony Settlement in Indiana for the last eight years of his life. It is said his simple habits and refusal to earn money caused problems for his family. Say succumbed to what appeared to by typhoid fever when he was just 47.

References:

Copper, P. 1977. Zygospira and some related Ordovician and Silurian atrypoid brachiopods. Palaeontology 20: 295-335.

Hall, J. 1862. Observations upon a new genus of Brachiopoda. Report New York State Museum, Natural History 15: 154-155.

Hall, J. 1867. Note upon the genus Zygospira and its relations to Atrypa. Report New York State Museum, Natural History 20: 267-268.

Sandy, M.R. 1996. Oldest record of peduncular attachment of brachiopods to crinoid stems, Upper Ordovician, Ohio, USA (Brachiopoda; Atrypida: Echinodermata; Crinoidea). Journal of Paleontology 70: 532-534.

Wooster’s Fossil of the Week: A tabulate coral from the Upper Ordovician of southern Ohio

December 18th, 2015

Calapoecia huronensis Billings, 1865 top 585We have here another fossil collected by a Wooster student on the August 2015 College of Wooster Invertebrate Paleontology field trip to Caesar Creek Lake, Ohio. Eduardo Luna picked up this specimen of the tabulate coral Calapoecia huronensis (Billings, 1865) from the Waynesville Formation (Upper Ordovician). For some reason in all my years of working in the Upper Ordovician, I’ve not come across this coral species before. Eduardo had sharp eyes as you can see it is rather small. The circular tubes are corallites, each of which held a coral polyp in life. This particular coral is distinctive for its septal spines along the inside rim of each corallite, giving them a beaded appearance.

Calapoecia huronensis Billings, 1865 bottom 585This is the underside of Eduardo’s coral. The corallites on the left side are eroded, showing the elongated septal spines that run lengthwise down their inside walls.

CNSPhoto-GEOLOGISTWe met the author of C. huronensis, Elkanah Billings (1820-1876), earlier this year, but why not show the handsome Canadian again? He originally described this coral species in 1865. He was Canada’s first government paleontologist, and he very much looked the part. Billings was born on a farm near Ottawa. He went to law school and became a lawyer in 1845, but he gave up stodgy law books for the bracing life of a field paleontologist. In 1856, Billings joined the Geological Survey of Canada, eventually naming over a thousand new species in his career. The Billings Medal is given annually by the Geological Association of Canada to the most outstanding of its paleontologists.

References:

Billings, E. 1865. Notice of some new genera and species of Palaeozoic fossils. Canadian Naturalist and Geologist, New Series 2: 432–452.

Browne, R.G. 1965. Some Upper Cincinnatian (Ordovician) colonial corals of north-central Kentucky. Journal of Paleontology 39: 1177-1191.

Cox, I. 1936. Revision of the genus Calapoecia Billings. Bulletin of the National Museum of Canada 80: 1–48.

Jull, R.K. 1976. Review of some species of Favistina, Nyctopora, and Calapoecia (Ordovician corals from North America). Geological Magazine 113: 457-467.

Wooster’s Fossil of the Week: A common trilobite from the Upper Ordovician of Ohio

December 11th, 2015

Flexicalymene meeki cephalon view 585This beautiful specimen was collected by Wooster student Eve Caudill on this year’s College of Wooster Invertebrate Paleontology field trip to Caesar Creek Lake, Ohio. It is the iconic trilobite Flexicalymene meeki (Foerste, 1910) from a soft, “buttery” shale in the Waynesville Formation (Upper Ordovician). This is one of the most common trilobite species in the world, and it has been photographed thousands of times, so I posed it at an unconventional, rakish angle. We are looking here at the cephalon (head) of the animal. I like the way the remnants of the enclosing sedimentary matrix cling to the low places, highlighting the bumps and ridges. The center of the cephalon shows the distinctive glabella with its side lobes. The stomach of the trilobite was housed underneath it. The two eyes are visible on either side of the glabella, the one on the right split by the slightly-open facial suture used for dividing its exoskeleton during molting (ecdysis).

Flexicalymene meeki pygidium view 585This is a view of the pygidium (tail end) of the same Flexicalymene meeki specimen. It is tucked under the leading edge of the cephalon in the classic enrollment position. Trilobites likely enrolled for several reasons, but the primary one was almost certainly to affect a pill-bug-like defense against predators.

Flexicalymene meeki side view 585This is a side view of the enrolled trilobite. The articulated segments between the cephalon and pygidium constitute the thorax.foerste-1936We met the author of Flexicalymene meeki four years ago in this blog, so let’s visit him again. August F. Foerste (1862-1936) was one of the pioneers of Cincinnatian paleontology and stratigraphy. He grew up and worked in the Dayton, Ohio, area. Foerste went to Denison University where he was a very successful undergraduate, publishing several geological papers. He returned to Dayton after graduation with a PhD from Harvard, teaching high school for 38 years. When he retired he was offered a teaching position at the University of Chicago, but instead went to work at the Smithsonian Institution until the end of his life.

A final note from the Invertebrate Paleontology class this year: We were greatly assisted by two fantastic paleontological websites, one by Alycia Stigall at Ohio University called The Digital Atlas of Ordovician Life, and the other by Steve Holland at the University of Georgia titled The Stratigraphy and Fossils of the Upper Ordovician near Cincinnati, Ohio. Thank you to my most excellent and productive colleagues.

References:

Brandt, D.S. 1993. Ecdysis in Flexicalymene meeki (Trilobita). Journal of Paleontology 67: 999-1005.

Brett, C.E., Thomka, J.R., Schwalbach, C.E., Aucoin, C.D. and Malgieri, T.J. 2015. Faunal epiboles in the Upper Ordovician of north-central Kentucky: Implications for high-resolution sequence and event stratigraphy and recognition of a major unconformity. Palaeoworld 24: 149-159.

Esteve, J., Hughes, N.C. and Zamora, S. 2011. Purujosa trilobite assemblage and the evolution of trilobite enrollment. Geology 39: 575-578.

Evitt, W.R. and Whittington, H.B. 1953. The exoskeleton of Flexicalymene (Trilobita). Journal of Paleontology 27: 49-55.

Foerste, A.F. 1910. Preliminary notes on Cincinnatian and Lexington fossils of Ohio, Indiana, Kentucky, and Tennessee. Denison University Science Laboratories Bulletin 16: 17-87.

Frey, R.C. 1987. The paleoecology of a Late Ordovician shale unit from southwest Ohio and southeastern Indiana. Journal of Paleontology 61: 242-267.

 

A True Liberal Arts Experience

December 9th, 2015

Guest Blogger: Mary Reinthal

If you were to poll the campus about their fall break, not many would say that they spent 20 hours over 2 days in an FTIR lab analyzing glass chips for volatile content. But if you were to ask geology senior Mary Reinthal and her advisor Dr. Meagen Pollock, that’s exactly what they would say. Fly in on a Monday; analyze samples at University of Massachusetts Amherst Tuesday and Wednesday; fly out Thursday. It was a lot of work, but somebody had to do it (for their Independent Study). The time was spent looking at the volatile spectra from individual, doubly polished glass chips collected from British Columbia, Canada.

Not a lot of windows in the FTIR lab, so Mary had to look at glass chips.

Not a lot of windows in the FTIR lab, so Mary had to look at glass chips.

After all that time in the lab, a lot of data were collected (yay!). These numbers will hopefully help us understand the evolution of glaciovolcanic tindars in British Columbia. Until then, however, these data will to be sifted through and looked at more closely as the semester continues.

Mary measuring thickness of glass wafers. To understand the bigger picture of volatile effects on eruptions you have to look small. Like micron-scale small.

Mary measuring thickness of glass wafers. To understand the bigger picture of volatile effects on eruptions you have to look small. Like micron-scale small.

Of course, the visit to U-Mass. Amherst wasn’t all science and glass chips. After finishing a 9-hour stint in the lab on Wednesday, Dr. Pollock and Mary ventured to Concord, Massachusetts to visit Walden Pond. In short, a truly liberal arts education was had by all.

Mary and Thoreau pondering life and science.

Mary and Thoreau pondering life and science.

 

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