Henri Temianka Correspondence; (kievman)

This collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_correspondence/3841/thumbnail.jp

Sub-Milankovitch cycles in periplatform carbonates from the early Pliocene Great Bahama Bank

High-resolution bulk sediment (magnetic susceptibility and aragonite content) and δ18O records from two different planktonic foraminifera species were analyzed in an early Pliocene core interval from the Straits of Florida (Ocean Drilling Program site 1006). The δ18O record of the shallow-dwelling foraminifera G. sacculifer and the aragonite content are dominated by sub-Milankovitch variability. In contrast, magnetic susceptibility and the δ18O record of the deeper-dwelling foraminifera G. menardii show precession cycles. The relationship between the aragonite and the paleoproxy data suggests that the export of sediment from the adjacent Great Bahama Bank was triggered directly by atmospheric processes rather than by sea level change. We propose a climate mechanism that bears similarities with the semiannual cycle component of eastern equatorial Pacific sea surface temperatures under present-day conditions

Match between late Pleistocene Great Bahama Bank and deep-sea oxygen isotope records of sea level

Throughout the Pliocene and Pleistocene, a hierarchy of sea-level fluctuations alternately flooded and exposed the Great Bahamas Bank, controlling its sedimentary evolution. The persistent rhythm of sea level is best shown in the upper Pleistocene to Holocene section in which 10 cycles of sea-level rise and fall are identified in core borings on the lee side of the bank. The same number of sea-level oscillations is indicated within the Brunhes chron of the deep-sea oxygen isotope record. In the Bahamas, sea-level oscillations are inferred from meter-scale parasequences of shallow-marine carbonates, interpreted largely as transgressive and highstand deposits, sandwiched between discontinuity horizons interpreted as subaerial-exposure horizons that developed during lower sea level. Subaerial exposure shifted from being largely restricted to the platform interior during the late Pliocene (Olduvai chron), to occurring across the entire lee side of the platform at the beginning of the Brunhes chron. This change on the platform is highly suggestive of the deep-sea oxygen isotope proxy of sea level which indicates a fundamental paleoclimatic shift at approximately the same time. Despite dating limitations, results from the Bahamian cores can be used to push the calibration of the sea-level record back to the late Pliocene

Interpreting carbonate and organic carbon isotope covariance in the sedimentary record

Many negative δ(13)C excursions in marine carbonates from the geological record are interpreted to record significant biogeochemical events in early Earth history. The assumption that no post-depositional processes can simultaneously alter carbonate and organic δ(13)C values towards more negative values is the cornerstone of this approach. However, the effects of post-depositional alteration on the relationship between carbonate and organic δ(13)C values have not been directly evaluated. Here we present paired carbonate and organic δ(13)C records that exhibit a coupled negative excursion resulting from multiple periods of meteoric alteration of the carbonate δ(13)C record, and consequent contributions of isotopically negative terrestrial organic matter to the sedimentary record. The possibility that carbonate and organic δ(13)C records can be simultaneously shifted towards lower δ(13)C values during periods of subaerial exposure may necessitate the reappraisal of some of the δ(13)C anomalies associated with noteworthy biogeochemical events throughout Earth history