Evan Kelly Modern analogs for ancient transpressional basin sedimentary deposits

● The Walden Creek Group ● Stratigraphy ● Olistostrome definition ● Tectonic Setting? ● Modern transtensional basins ● Sea of Marmara ● Korea ● Baja California ● Conclusions: do they match? Outline

Wilhite – 1000 m sandy silt/cgl carbonate olistostromes Shields- 750 m white pbl cgl + lenses course ss Licklog – 100 m siltstone / shale Walden Creek Group – Blue Ridge

An accumulation of submarine gravity flows as (semi-fluid bodies) Lack true bedding, yet are intercalated between normal sedimentary bedding sequences. Olistostromes

Wilhite – fossils in olistostromes Walden Creek Group: Age Unrug et al 2000

Wu et al. 2009

Modern Transtensional Basins ● Sea of Marmara ● Korea ● Gulf of California

Anatolia Carton et al. 2007

Anatolia Carton et al. 2007

Anatolia – Sea of Marmara Wong et al 1995

Anatolia – Sea of Marmara Wong et al 1995

Anatolia – Sea of Marmara Wong et al 1995

South Korea Chough et al. 2010

S. Korea - Eumsung Basin SW SE

Gulf of California

Gulf of CA - San Jose Island Umhoefer et al. 2007

Conclusions/Further Issues ● Basin geometry is central to the expected facies patterns in transtensional basins ● Olistostromes reasonable IF rapid change in fault offset ● Otherwise, don't match other megabreccias ● On what was WCG deposited? ● How much of WCG is missing?

● Carton, H., Singh, S.C., Hirn, A., Bazin, S., de Voogd, B., Vigner, A., Ricolleau, A., Cetin, S., Ocakoglu, N., Karakoc, F., Sevilgen, V., Seismic imaging of the three-dimensional architecture of the Cinarcik Basin along the North Anatolian Fault. Journal of Geophysical Research 112, ● Ryang, W.H., Contrasting basin fills in a strike-slip setting, Eumsung Basin, Korea. Geosciences Journal 7, ● Ryang, W.H., Chough, S.K., Alluvial-to-lacustrine systems in a pull-apart margin: southwestern Eumsung Basin, Korea. Sedimentary Geology 127, ● Umhoefer, P.J., Schwennicke, T., Del Margo, M.T., Ruiz-Geraldo, G., Ingle, J.C.J., McIntosh, W., Transtensional fault-termination basins: an important basin type illustrated by the Pliocene San Jose Island basin and related basins in the southern Gulf of California, Mexico. Basin Research 19, ● Unrug, R., Ausich, W.I., Bednarczyk, J., Cuffey, R.J., Mamet, B.L., Palmes, S.L., Unrug, S., Paleozoic age of the Walden Creek Group, Ocoee Supergroup, in the western Blue Ridge, southern Appalachians: Implications for evolution of the Appalachian margin of Laurentia. Geological Society of America Bulletin 112, ● Wong, H.K., Ludmann, T., Ulug, A., Gorur, N., The Sea of Marmara: a plate boundary sea in an escape tectonic regime. Tectonophysics 244, ● Wu, J.E., McClay, K., Whitehouse, P., Dooley, T., D analogue modelling of transtensional pull-a-apart basins. Marine and Petroleum Geology 26.8, References