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Titolo:
Diagenetic comparisons between non-tropical Cenozoic limestones of New Zealand and tropical Mississippian limestones from Indiana, USA: Is the non-tropical model better than the tropical model?
Autore:
Dodd, JR; Nelson, CS;
Indirizzi:
Indiana Univ, Dept Geol Sci, Bloomington, IN 47405 USA Indiana Univ Bloomington IN USA 47405 Geol Sci, Bloomington, IN 47405 USA Univ Waikato, Dept Earth Sci, Hamilton, New Zealand Univ Waikato Hamilton New Zealand Dept Earth Sci, Hamilton, New Zealand
Titolo Testata:
SEDIMENTARY GEOLOGY
fascicolo: 1-2, volume: 121, anno: 1998,
pagine: 1 - 21
SICI:
0037-0738(199810)121:1-2<1:DCBNCL>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
SKELETAL CARBONATE SEDIMENTS; COOL-WATER; TEMPERATE CARBONATES; SOUTHERN AUSTRALIA; SEAWATER CHEMISTRY; BURIAL DIAGENESIS; EUCLA PLATFORM; NEW-MEXICO; SHELF; CEMENTATION;
Keywords:
limestone; diagenesis; Cenozoic; Mississippian; Indiana; New Zealand;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
96
Recensione:
Indirizzi per estratti:
Indirizzo: Dodd, JR Indiana Univ, Dept Geol Sci, Bloomington, IN 47405 USA Indiana Univ Bloomington IN USA 47405 Bloomington, IN 47405 USA
Citazione:
J.R. Dodd e C.S. Nelson, "Diagenetic comparisons between non-tropical Cenozoic limestones of New Zealand and tropical Mississippian limestones from Indiana, USA: Is the non-tropical model better than the tropical model?", SEDIMENT GE, 121(1-2), 1998, pp. 1-21

Abstract

Mississippian limestones exposed in Indiana, U.S.A., were deposited in a shallow tropical ocean. However, many properties of these limestones are more like those of modem and Cenozoic non-tropical limestones such as those found in New Zealand. The dominant skeletal grains in the Indiana limestones are calcitic echinoderms, bryozoans, and brachiopods. The dominant skeletalgrains in most Cenozoic limestones of New Zealand are calcitic bryozoans, echinoderms, bivalve molluscs, and foraminifera. In contrast, modern and Cenozoic tropical limestones contain an abundance of aragonitic green algae, corals, and molluscs. Early in diagenesis the metastable aragonite dissolves and reprecipitates as calcite, causing early cementation of the sediments. Originally aragonitic fossils that have dissolved can be identified as molds that are commonly filled with secondary calcite. Because they containedlittle aragonite, most of the Indiana and New Zealand limestones did not have an abundant source of early cement, Except for local cases in which grains were cemented in contact with carbonate supersaturated seawater, grainstones were relatively deeply buried with little cement between the grains. This resulted in mechanical and chemical compaction of skeletal grains, producing a 'fitted fabric' with greatly reduced pore space, either open or filled with cement between the grains. Cement in these aragonite-poor grainstones comes largely from pressure dissolution between grains and along stylolitic seams in the rock, features that are common only after burial beyond a few hundred meters. The final product of deeply buried (up to 2000 m) Cenozoic New Zealand grainstones is similar to the Mississippian grainstones of Indiana. In the Indiana limestones we have only the final product of thisextensive burial diagenesis. However, the New Zealand sediments and rocks reveal all steps of formation of the final deeply buried limestone. The reason for the scarcity of originally aragonitic fossil grains in Paleozoic rocks worldwide is unknown. Organisms with aragonitic skeletons such as some molluscan groups and calcareous green algae were present, but seldom in much abundance. The aragonitic scleractinian corals had not yet evolved. Previous researchers have noted that non-skeletal precipitates such as ooids andcements have at times during the Paleozoic been predominantly aragonite and at other times calcite. They have attributed this difference to secular variation in seawater chemistry (icehouse vs. greenhouse seas). Abundance ofaragonitic and calcitic skeletal grains does not follow this pattern. (C) 1998 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 04:01:00