عنوان

The weathering of dolomite marble on Thasos, Greece

شماره

TLpq304098482

زبان متن نوشتاري يا گفتاري و مانند آن

انگلیسی

عنوان اصلي

The weathering of dolomite marble on Thasos, Greece

نام عام مواد

[Thesis]

نام نخستين پديدآور

E. F. Doehne

نام ساير پديدآوران

J. F. Mount

نام ناشر، پخش کننده و غيره

University of California, Davis

تاریخ نشرو بخش و غیره

1994

نام خاص و کميت اثر

224

جزئيات پايان نامه و نوع درجه آن

Ph.D.

کسي که مدرک را اعطا کرده

University of California, Davis

امتياز متن

1994

متن يادداشت

Studies of archaeologically-dated carbonate surfaces on the islands of Cyprus and Thasos, Greece show that there are significant differences in the pathways, conditions and time-scales of the weathering reactions affecting these 1800-2700 year-old surfaces. Electron microprobe analyses of tesserae from ancient mosaics at Paphos, Cyprus indicate that several diagenetic processes are responsible for recent color changes of the mosaic surfaces. Some white limestone tesserae are stained by hydrated iron oxides due to the oxidation of small pyrite inclusions. Other limestone tesserae have thin, friable surface layers due to the formation of gypsum crusts. Studies of ancient marble surfaces on Thasos, Greece have provided information on three surficial carbonate reactions: dedolomitization, microstromatolite growth, and oxalate crust formation. The three reactions each differ by approximately an order of magnitude in net accumulation rate for surfaces exposed for 1900-2700 years. Net accumulation rates are fastest for microstromatolites (averaging 0.39 mum/yr.), slower for dedolomitization (0.05 mum/yr.), and are slowest for oxalate crusts (0.004 mum/yr.). Microstromatolite growth is related to seasonal seeps and small streams that support the development of algal mats on quarry surfaces. Due to their low solubility and dense, fine-grained structure, calcium oxalate crusts on Thasos appear to retard carbonate dissolution. The unexpected low-temperature dedolomitization of dolomite marble surfaces on Thasos can be explained by a model incorporating the preferential dissolution of calcite and possible uptake of Mg by microorganisms leading to a fluid with a high Ca/Mg activity ratio. Experiments show dedolomitization can occur in less than a week at elevated temperatures and is primarily a function of solution Ca/Mg, although dolomite crystal orientation and defects are also important. Dedolomitization experiments at 50 and 80C show that both fine and coarse-scale dedolomitization can occur simultaneously in different microenvironments on the same sample. Weathering crusts similar to those found on Thasos were documented in samples from Greek and Roman dolomite marble monuments and sculpture, suggesting that these reactions play an important role in marble preservation.

موضوع مستند نشده

Earth sciences

موضوع مستند نشده

Geochemistry

موضوع مستند نشده

Geology

موضوع مستند نشده

Geology

مستند نام اشخاص تاييد نشده

E. F. Doehne

مستند نام اشخاص تاييد نشده

J. F. Mount

نام الکترونيکي

فرمت انتشار

p

نوع ماده

[Thesis]

کد کاربرگه

276903

سطح دسترسي

a

تكميل شده

Y