Journal Article

Ordovician reef and mound evolution: the Baltoscandian picture

HINTS, LINDA, LEHNERT, OLIVER, KRÖGER, BJÖRN

2017

Overview

The widespread growth of reefs formed by a framework of biogenic constructors and frame-lacking carbonate mounds began on Baltica during Ordovician time. Previously, Ordovician reef and mound development on Baltica was considered to be sporadic and local. A review of all known bioherm localities across the Baltic Basin reveals a more consistent pattern. Ordovician bioherms grew in a wide E–W-aligned belt across the Baltic Basin and occur in several places in Norway. Substantial reef development began simultaneously across the region during the late Sandbian – early Katian interval and climaxed during the late Katian Pirgu age. The current spatiotemporal distribution of bioherms is a result of interdependent factors that involve original drivers of reef development such as relative sea level, climate during the time of deposition and effects of post-depositional erosion. Oceanographic conditions were likely more favourable during times of cooler global climates, low sea level and glacial episodes. At the same time, the likelihood that bioherms are preserved from long-term erosion is higher when deposited during low sea level in deeper parts of the basin. A main factor controlling the timing of the reef and mound evolution was Baltica's shift toward palaeotropical latitudes during Late Ordovician time. The time equivalence between initial reef growth and the Guttenberg isotope carbon excursion (GICE) suggests that global climatic conditions were important.

• Publisher: Cambridge University Press
• Subject: Age composition / Algae / Anthozoa / assemblages / Atlantic Ocean / Baltic region / Baltic Sea / basin analysis / basins / biodiversity / biogenic structures / Bioherms / C-13/C-12 / carbon / carbonate platforms / carbonate rocks / Carbonates / chemostratigraphy / Climate / Climatic conditions / Cnidaria / Current distribution / deposition / depositional environment / Earth and Related Environmental Sciences / Erosion / Europe / Evolution / Frameworks / Geological time / Geology / Geovetenskap och relaterad miljövetenskap / Global climate / Great Ordovician Biodiversification Event / Invertebrata / Islands / isotope ratios / Isotopes / Katian / marine sedimentation / Mounds / Multidisciplinary Geosciences / Multidisciplinär geovetenskap / Natural Sciences / Naturvetenskap / North Atlantic / Ordovician / Original Articles / paleoclimatology / paleoecology / paleoenvironment / Paleozoic / Pirgu / Plate tectonics / Reefs / Sandbian / Sea level / sea-level changes / sed rocks, sediments / Sedimentary petrology / sedimentary rocks / sedimentary structures / sedimentation / Sediments / Spatial distribution / stable isotopes / Stratigraphy / Temporal distribution / Upper Ordovician