Boring bivalve traces in modern reef and deeper-water macroid and rhodolith beds

Macroids and rhodoliths, made by encrusting acervulinid foraminifera and coralline algae, are widely recognized as bioengineers providing relatively stable microhabitats and increasing biodiversity for other species. Macroid and rhodolith beds occur in different depositional settings at various localities and bathymetries worldwide. Six case studies of macroid/rhodolith beds from 0 to 117m water depth in the Pacific Ocean (northern Central Ryukyu Islands, French Polynesia), eastern Australia (Fraser Island, One Tree Reef, Lizard Island), and the Mediterranean Sea (southeastern Spain) show that nodules in the beds are perforated by small-sized boring bivalve traces (Gastrochanolites). On average, boring bivalve shells (gastrochaenids and mytilids) are more slender and smaller than those living inside shallow-water rocky substrates. In the Pacific, Gastrochaena cuneiformis, Gastrochaena sp., Leiosolenus malaccanus, L. mucronatus, L. spp., and Lithophaga/Leiosolenus sp., for the first time identified below 20m water depth, occur as juvenile forms along with rare small-sized adults. In deep-water macroids and rhodoliths the boring bivalves are larger than the shallower counterparts in which growth of juveniles is probably restrained by higher overturn rates of host nodules. In general, most boring bivalves are juveniles that grew faster than the acervulinid foraminiferal and coralline red algal hosts and rarely reached the adult stage. As a consequence of phenotypic plasticity, small-sized adults with slow growth rates coexist with juveniles. Below wave base macroids and rhodoliths had the highest amounts of bioerosion, mainly produced by sponges and polychaete worms. These modern observations provide bases for paleobiological inferences in fossil occurrences.Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) 25247083Erasmus+FAR2012-2017FIR2016FIR2018PRIN "Biotic resilience to global change: biomineralization of planktonic and benthic calcifiers in the past, present and future" 2017RX9XXXYBioMed Central-Prepay Membership at the University of FerraraJunta de Andalucía RNM 190Committee on ResearchMuseum of PaleontologyDepartment of Integrative Biology, UC BerkeleyUC Pacific Rim Projec

Palynology of Early Cretaceous (Barremian to Aptian) hydrocarbon (methane) seep carbonates and associated mudstones, Wollaston Forland, Northeast Greenland

Palynostratigraphic and palynofacies analysis have been performed on hydrocarbon seep carbonate, carbonate nodule and mudstone samples from the Early Cretaceous Kuhnpasset Beds in the Kuhnpasset area of Wollaston Forland, Northeast Greenland. Three informal palynostratigraphic zones have been defined based on dinoflagellate cyst occurrences. The zones range from ?early Barremian to early Aptian in age, and correlate with previously defined dinoflagellate cyst zones in Northeast Greenland. These zones indicate hydrocarbon seepage in Kuhnpasset spanned the ?early–late Barremian age range, but did not continue into the Aptian, and thus seep activity continued for as much as three million years. Palynofacies analysis is used to interpret the depositional environment of the Kuhnpasset Beds and indicate that the hydrocarbon seeps and associated mudstones from this sedimentary sequence were deposited in a proximal shelf setting

Structural evolution and basin architecture of the Traill Ø region, NE Greenland: A record of polyphase rifting of the East Greenland continental margin

Fault block basins exposed along NE Greenland provide insights into the tectonic evolution of East Greenland and the Norwegian-Greenland Sea. We present a new geological map and cross sections of the Traill Ø region, NE Greenland, which formed the western margin of the Vøring Basin prior to Cenozoic seafloor spreading. Observations support a polyphase rift evolution with three rift phases during Devonian-Triassic, Jurassic-Cretaceous, and Cenozoic time. The greatest amounts of faulting and block rotation occurred during Cenozoic rifting, which we correlate with development of the continent- ocean transition after ca. 56 Ma and the Jan Mayen microcontinent after ca. 36 Ma. A newly devised macrofaunal-based stratigraphic framework for the Cretaceous sandy mudstone succession provides insights into Jurassic- Cretaceous rifting. We identify a reduction in sedimentation rates during the Late Cretaceous; this corresponds to a transition from structurally confined to unconfined sedimentation that coincides with increased clastic sedimentation to the Vøring and Møre Basins derived from East Greenland. With each rift phase we record an increase in the number of active faults and a decrease in the spacing between them. We attribute this to fault block rotation that leads to an excess build-up of stress that can only be released by the creation of new steep faults. In addition, we observe a stepwise migration of deformation toward the rift axis that we attribute to preexisting lithospheric heterogeneity that was modified during subsequent rift and post-rift phases. Such observations are not readily conformable to classic rift evolution models and highlight the importance of post-rift lithospheric processes that occur during polyphase rift evolution

Structural evolution and basin architecture of the Traill Ø region, NE Greenland: A record of polyphase rifting of the East Greenland continental margin

Fault block basins exposed along NE Greenland provide insights into the tectonic evolution of East Greenland and the Norwegian-Greenland Sea. We present a new geological map and cross sections of the Traill Ø region, NE Greenland, which formed the western margin of the Vøring Basin prior to Cenozoic seafloor spreading. Observations support a polyphase rift evolution with three rift phases during Devonian-Triassic, Jurassic-Cretaceous, and Cenozoic time. The greatest amounts of faulting and block rotation occurred during Cenozoic rifting, which we correlate with development of the continent- ocean transition after ca. 56 Ma and the Jan Mayen microcontinent after ca. 36 Ma. A newly devised macrofaunal-based stratigraphic framework for the Cretaceous sandy mudstone succession provides insights into Jurassic- Cretaceous rifting. We identify a reduction in sedimentation rates during the Late Cretaceous; this corresponds to a transition from structurally confined to unconfined sedimentation that coincides with increased clastic sedimentation to the Vøring and Møre Basins derived from East Greenland. With each rift phase we record an increase in the number of active faults and a decrease in the spacing between them. We attribute this to fault block rotation that leads to an excess build-up of stress that can only be released by the creation of new steep faults. In addition, we observe a stepwise migration of deformation toward the rift axis that we attribute to preexisting lithospheric heterogeneity that was modified during subsequent rift and post-rift phases. Such observations are not readily conformable to classic rift evolution models and highlight the importance of post-rift lithospheric processes that occur during polyphase rift evolution