Condensed sections are associated commonly with apparent marine hiatuses and 

 often occur as thin, but continuous, zones of burrowed, slightly lithified 

 beds (omission surfaces)or as marine hardgrounds . In addition, condensed 

 sections may be characterized by abundant and diverse planktonic and benthic 

 microfossil assemblages, authigenic minerals (such as glauconite, phosphorite, 

 and siderite) , organic matter, and bentonites and may possess greater 

 concentrations of platinum elements such as iridium. Condensed sections are 

 important because they tie the temporal stratigraphic framework provided by 

 open-ocean microfossil zonations to the physical stratigraphy provided by 

 depositional sequences in shallower, more landward sections. Condensed 

 sections represent a physical stratigraphic link between shallow- and deep- 

 water sections and are recognized by the analysis of seismic, well-log, and 

 outcrop data. Within each depositional sequence, condensed sections are best 

 recognized and utilized within an area from the shelf/slope break landward to 

 the distal edge of inner neritic-sand deposition. Where sedimentation rates 

 are generally low, as in the deep oceanic, a number of condensed sections may 

 coalesce to form a composite condensed section. Data from detailed analyses 

 of continental -margin condensed sections are presented to illustrate the 

 nature and importance of condensed sections for dating and correlating 

 continental -margin sequences and reconstructing ancient depositional 

 environments. (Authors). 



196 LOUTIT, T. S., and KENNETT. J. P. 1981. "New Zealand and Australian 

 Cenozoic Sedimentary Cycles and Global Sea-Level Changes," American 

 Association of Petroleum Geologists . Bulletin 65, No. 9, pp 1586-1601. 



A global sea-level history determined by Vail et al consists of 23 sea- 

 level cycles between the base of the Cenozoic and the Pliocene-Pleistocene 

 boundary (65 to 1.8 Ma). We have examined the relation between this global 

 sea- level history and the New Zealand and Australian continental margin 

 shallow-marine sedimentary record. 



Sedimentary cycles in the Australian Cenozoic marginal -marine sequences 

 are bounded by unconformities of various durations. The tectonic stability 

 and aridity of the western and southwestern margin of Australia during the 

 Cenozoic produced a sedimentary record dominated by hiatuses. This contrasts 

 with the relatively complete sequences of the tectonically more active south- 

 eastern marginal basins. The four major sedimentary cycles in the Australian 

 Cenozoic (Paleocene to early Eocene; middle to late Eocene; latest Oligocene 

 to late middle Miocene; and latest Miocene to Quaternary) correlate with the 

 supercycles Ta, Tb , Tc, Td, and Te of Vail et al . 



In New Zealand most of the Cenozoic stages represent classic sedimentary 

 cycles bounded by unconformities or correlative conformities formed as a 

 result of large, rapid eustatic sea-level changes. The marine Tertiary 

 sequence in New Zealand consists of 23 stages. Of the 18 stage boundaries 

 between the end of the Paleocene (53 Ma) and the end of the Miocene (5 Ma), 16 

 appear to correlate with the boundaries of eustatic sea- level cycles. 



Eustatic sea- level lowstands are well recorded (as unconformities) in 

 New Zealand as a result of its unique tectonic setting during the Cenozoic. 

 For most of the early Cenozoic until the middle Oligocene (-30 Ma) New Zealand 

 was generally subsiding. After the middle Oligocene this region began to be 

 uplifted as the Pacific-Australian plate boundary migrated onto New Zealand, 



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