Speakers Club: Samantha Gwizd, Miranda Stripe and Luyuan Ding

Event Date: 

Thursday, May 14, 2015 - 2:00pm

Event Location: 

  • Webb Hall 1100

Samantha Gwizd, Miranda Stripe and Luyuan Ding, all three of whom are UCSB graduate students, will give talks at Speakers Club on Thursday.  Samantha's talk is entitled Paleoceanography of the Eastern Equatorial Pacific Ocean: Dissolution cycles in the stratigraphic record, Miranda's talk is entitled Enigmatic fossils from the middle Cambrian of Australia and Luyuan's talk is entitled Stress Drop Uncertainty for Central California Earthquakes.

Samantha's ABSTRACT:

The Eastern Equatorial Pacific (EEP) Ocean is a dynamic and variable region in terms of water masses, biological productivity, temperature gradients, and its response to climate change. Past studies of the paleoceanography of the EEP commonly use stable oxygen isotopes of CaCO3 foraminifera tests to establish the isotope “stratigraphy” of sediment cores and evaluate glacial-interglacial fluctuations throughout the Pleistocene.  We seek to establish a temporal link between glacial cyclicity and changes in ocean chemistry within the EEP over the past 720 kyr (The Middle and Upper Pleistocene). We present a new stable isotope record generated using the benthic foraminifera C. wuellerstorfi from giant piston core CDH-36 (3° 35.85’ S, 83° 57.79’ W; 3225 m), cored from the Carnegie Platform south of the Galapagos Islands. This core triples the timespan of other cores previously studied at this site (Shackleton et al., 1988; Martin et al., 2002). We measured four radiocarbon dates and stable oxygen isotopes throughout the core to establish the chronology of CDH-36 by aligning it with the LR04 Benthic Stack (Lisiecki and Raymo, 2005). The record is then evaluated alongside %Coarse Fraction (%CF), the sand-sized fraction (>150 micrometers) in each sample. %CF is a common physical proxy for CaCO3 dissolution, and exhibits similar cyclicity to glacial-interglacial cycles and changing sedimentation rates in CDH-36, thus representing the influence of Pleistocene climate on the CaCO3 cycle.


Miranda's ABSTRACT:

The Cambrian marked a significant rise in metazoan morphological diversity and disparity, making the investigation of its taxa essential to understanding the evolution of modern groups. Middle Cambrian fauna of the Monastery Creek Formation (MCF) in the Georgina Basin, Australia have been studied by numerous authors. Many of these small shelly fossils have been securely assigned to various higher taxa, including brachiopods, molluscs, and hyoliths. Others, however, many of them remaining to be described, have defied taxonomic placement and are considered problematica. Herein I describe a collection of unidentified tubular-shelled and net-like fossils from the MCF, including their microstructure and morphology. The former resemble orthothecid hyoliths, while the latter likely represent fragments of echinoderm ossicles.


Luyuan's ABSTRACT:


Samantha Gwizd, Miranda Stripe and Luyuan Ding