Dedolomitization of the Cambrian Ledger and Kinzers Formations, York County, PA
Abstract
The Great American Bank, deposited off the coast of Laurentia in the Cambrian
and Ordovician consists of over 3000 meters of carbonate deposits, and in these deposits
the early history of the North American continent is preserved (Matter, 1966). These
deposits provide us, 500 million years later, with an understanding of the natural
processes that have occurred in the area. This paper builds upon previous studies
conducted at the LWB Refractories in York, PA, on the Middle Cambrian Ledger
Formation. This study analyses the dedolomitized facies through petrographic and
geochemical studies. Dedolomitization is the calcitization of dolomite (Carozzi, 1993).
Petrographic and geochemical data is used to understand the process of dedolomitization
and the environment in which these deposits formed.
Isotopic and trace element data supports field and petrographic observations of
localized calcitization of Ledger dolomite deposits. By comparing the data from the
dedolomitized samples to data from dolomite of the Ledger Formation (Dinterman, 1998)
we are able to understand the process of dedolomitization in relation to other diagenetic
processes the deposits have undergone.
Geochemical data indicate that the diagenetic fluids responsible for the
dedolomitization were primarily low temperature meteoric waters. Geochemical data of
the dolomite suggest the formation occurred through deep burial and warm waters
(Dinterman, 1998). The presence of the Triassic unconformity directly overlying the
dedolomite deposits suggest they formed after regional rifting, allowing for the
introduction of meteoric water along faults. This supports the near surface model for
dedolomitization (Carozzi, 1993).
Description
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2008
Collections
- F&M Theses Collection [322]