Marcelle K. BouDagher-Fadel

Timing of India‐Asia collision: Geological, biostratigraphic, and palaeomagnetic constraints

[1] A range of ages have been proposed for the timing of India-Asia collision; the range to some extent reflects different definitions of collision and methods used to date it. In this paper we discuss three approaches that have been used to constrain the time of collision: the time of cessation of marine facies, the time of the first arrival of Asian detritus on the Indian plate, and the determination of the relative positions of India and Asia through time. In the Qumiba sedimentary section located south of the Yarlung Tsangpo suture in Tibet, a previous work has dated marine facies at middle to late Eocene, by far the youngest marine sediments recorded in the region. By contrast, our biostratigraphic data indicate the youngest marine facies preserved at this locality are 50.6–52.8 Ma, in broad agreement with the timing of cessation of marine facies elsewhere throughout the region. Double dating of detrital zircons from this formation, by U-Pb and fission track methods, indicates an Asian contribution to the rocks thus documenting the time of arrival of Asian material onto the Indian plate at this time and hence constraining the time of India-Asia collision. Our reconstruction of the positions of India and Asia by using a compilation of published palaeomagnetic data indicates initial contact between the continents in the early Eocene. We conclude the paper with a discussion on the viability of a recent assertion that collision between India and Asia could not have occurred prior to ∼35 Ma.

The Cretaceous-Tertiary biotic transition

Mass extinctions are recognized through the study of fossil groups across event horizons, and from analyses of long-term trends in taxonomic richness and diversity. Both approaches have inherent flaws, and data that once seemed reliable can be readily superseded by the discovery of new fossils and/or the application of new analytical techniques. Herein the current state of the Cretaceous-Tertiary (K-T) biostratigraphical record is reviewed for most major fossil clades, including: calcareous nannoplankton, dinoflagellates, diatoms, radiolaria, foraminifera, ostracodes, scleractinian corals, bryozoans, brachio-pods, molluscs, echinoderms, fish, amphibians, reptiles and terrestrial plants (macrofossils and palynomorphs). These reviews take account of possible biasing factors in the fossil record in order to extract the most comprehensive picture of the K-T biotic crisis available. Results suggest that many faunal and floral groups (ostracodes, bryozoa, ammonite cephalopods, bivalves, archosaurs) were in decline throughout the latest Maastrichtian while others (diatoms, radiolaria, benthic foraminifera, brachiopods, gastropods, fish, amphibians, lepidosaurs, terrestrial plants) passed through the K-T event horizon with only minor taxonomic richness and/or diversity changes. A few microfossil groups (calcareous nannoplankton, dinoflagellates, planktonic foraminifera) did experience a turnover of varying magnitudes in the latest Maastrichtian-earliest Danian. However, many of these turnovers, along with changes in ecological dominance patterns among benthic foraminifera, began in the latest Maastrichtian. Improved taxonomic estimates of the overall pattern and magnitude of the K-T extinction event must await the development of more reliable systematic and phylogenetic data for all Upper Cretaceous clades.

The early evolutionary history of planktonic foraminifera

List of Contributors. Preface and Acknowledgements. 1. Introduction M.K. BouDagher-Fadel, et al. 2.The Jurassic Favusellacea, the Earliest Globigerinina M.D. Simmons, et al. 3. The Early Cretaceous Families M.K. BouDagher-Fadel, et al. 4. The Favusellidae-the Cretaceous Acme of the Favusellacea M.K. BouDagher-Fadel, et al. 5. The Practical Taxonomy of the Praehedbergellidae M.K. BouDagher-Fadel, et al. 6. The Earliest Praehedbergellidae-Gorbachikella M.K. BouDagher-Fadel et al. 7. The Flowering of the Praehedbergellidae: Praehedbergella M.K. BouDagher-Fadel, et al. 8. Blefuscuiana, The Longest Ranging and Most Diverse of the Praehedbergellidae M.K. BouDagher-Fadel, et al. 9. The Praehedbergellidae with Elongate Chambers-Lilliputianella, Lilliputianelloides gen.nov. and Wondersella. M.K. BouDagher-Fadel, et al. 10. The Planispiral Schackoinidae (Blowiella, Claviblowiella gen.nov., Globigerinelloides, Leupoldina and Schackoina M.K. BouDagher-Fadel, et al. 11. The Evolution of the Hedbergellidae M.K. BouDagher-Fadel, et al. 12. The Evolution of the Planomalinidae M.K. BouDagher-Fadel, et al. 13. Aspects of the Probable Physiology and Ecology of the Praehedbergellidae, Aided by Studies of Living Globigerinaccea M.K. BouDagher-Fadel, et al. Appendix. References.

Xigaze forearc basin revisited (South Tibet): Provenance changes and origin of the Xigaze Ophiolite

Our new stratigraphic, sedimentological, and micropaleontological analysis, integrated with basalt geochemistry, sandstone petrography, and detrital-zircon U-Pb and Hf isotope data, suggests the revision of current models for the geological evolution of the Asian active margin during the Cretaceous. The Xigaze forearc basin began to form in the late Early Cretaceous, south of the Gangdese arc, during the initial subduction of the Neotethyan oceanic lithosphere under the Lhasa terrane. Well-preserved stratigraphic successions document the classical upwardshallowing pattern of the forearc-basin strata and elucidate the origin of the associated oceanic magmatic rocks. The normal midocean-ridge basalt (N-MORB) geochemical signature and stratigraphic contact with the overlying abyssal cherts (Chongdui Formation) indicate that the Xigaze Ophiolite formed by forearc spreading and represents the basement of the forearc sedimentary sequence. Volcaniclastic sedimentation began with thick turbiditic sandstones and interbedded shales in the late Albian–Santonian (Ngamring Formation) followed by shelfal, deltaic, and fl uvial strata (Padana Formation), with fi nal fi lling of the basin by the Campanian age. Forearc sandstones do not show the classical trend from feldspatholithic volcaniclastic to quartzo-feldspathic plutoniclastic compositions, indicating limited unroofi ng of the Gangdese arc prior to collision. U-Pb age spectra of detrital zircons are unimodal with a 107 Ma peak in the lower Ngamring Formation (104–99 Ma), bimodal with a subordinate additional peak at 157 Ma in the middle Ngamring Formation (99– 88 Ma), and multimodal with more abundant pre-Mesozoic ages in the upper Ngamring and Padana Formations (88–76 Ma). These three petrofacies with distinct provenances document the progressive erosional evolution of the Gangdese arc, with uplift of the central Lhasa terrane and expanding river catchments to include the central Lhasa terrane during the Late Cretaceous.

A revision of some larger foraminifer of the Miocene of southeast Kalimantan

Larger benthic foraminifera from the upper part of the lower Miocene to the middle Miocene, upper Burdigalian-Serravallian (Tf1-Tf2), from previously unstudied sections in East Kalimantan are described and figured. Lepidocyclina praedelicata is described as a new species. This comprises a new ancestral link in the evolution of the Lepidocyclina from L. praedelicata in the early Miocene (Burdigalian; uppermost Te to lower Tf1) into L. delicata in the middle Miocene (Serravallian; Tf2). Analysis of the larger benthic foraminifera has allowed accurate dating of the carbonate sections studied using the East Indian Letter Classification.

Geology of the Cenozoic Indus Basin sedimentary rocks: Paleoenvironmental interpretation of sedimentation from the western Himalaya during the early phases of India-Eurasia collision

This study reassesses the stratigraphy, sedimentology, and provenance of the Indus Basin sedimentary rocks, deposited within the Indus Tsangpo Suture Zone (ITSZ) during the early phases of India-Eurasia collision. Using field observations, biostratigraphy, and petrographic and isotopic analyses we create a paleodepositional reconstruction within the paleotectonic setting of the early phases of India-Eurasia collision. We then re-examine existing constraints to the timing of India-Eurasia collision previously interpreted from the earliest occurrence of mixed Indian- and Eurasian-derived detritus in the succession. From mid-Cretaceous to early Paleocene times the Jurutze and Sumda Formations were deposited within an arc-bounded marine basin between the Dras and Kohistan-Ladakh Island arcs. The <51 Ma aged deltaic Chogdo Formation then filled the basin until deposition of the 50.8–49.4 Ma aged Nummulitic Limestone during a marine incursion, before continental facies developed in an evolving intermountain basin with the deposition of the Paleogene Indus Group. Within these systems, sediment was sourced from the Eurasian margin to the north and was transported southward into the suture zone. In this section, we see no unequivocal evidence of Indian Plate input to the sedimentary succession (and thus no evidence of mixed Indian-Eurasian-derived detritus indicative of India-Asia collision) until the upper stratigraphic horizons of the Indus Group, when facies are representative of an axial, northwesterly flowing river system. We suggest that the paleo-Indus River was initiated within the ITSZ during late Oligocene-early Miocene times. Sedimentation of the Indus Group continued until the late Miocene.

Revision of the stratigraphic significance of the oligocene-miocene “Letter-Stages”

Abstract A new correlation is proposed between the “Letter Stages” of the Far East, the Planktonic Foraminiferal Zones of the Oligocene-Miocene and the European Stages. Constructive criticisms are invited.

Chapter 1 Biology and evolutionary history of larger benthic foraminifera

Publisher Summary Larger foraminifera are biologically complex and highly versatile. They are both robust but can be highly specialized and therefore highly sensitive to their environment. Their study provides, as a result, considerable insights into evolutionary process as well as into the major geological mechanisms associated with extinction and recovery. Larger foraminifera also have and continue to occupy the very important ecological niche of being a reef-forming group. The worldwide distribution of carbonate biota, especially reef biota, contains important information on the environmental factors, including oceanographic parameters, which control this most sensitive of habitats. The study of the distribution patterns of this niche, over different time slices, provides valuable information on how the climate of the Earth has evolved in the past 350 Ma. Finally, the carbonate-rich shallow marine and reef environments favored by larger foraminifera are also those that may give rise to economically vital deposits of oil and gas. So larger foraminifera are now central to our ability to date, correlate and analyze the sedimentary basins that are the key to the economic well-being of the world. A detailed understanding of the taxonomy of the larger foraminifera is essential, therefore, for any applied biostratigraphic analysis.

Lower Jurassic Foraminifera and Calcified Microflora from Gibraltar, Western Mediterranean

Benthic foraminifera are described for the first time from the Gibraltar Limestone Formation of the Rock of Gibraltar. The new species Siphovalvulina colomiS. gibraltarensisRiyadhella praeregularis occur with Duotaxis metula Kristan, Everticyclammina praevirguliana Fugagnoli, Siphovalvulina sp.,an atypically early example of Textulariopsis sp., and Nodosaria sp. Microflora are present as the probable cyanobacterium Cayeuxia ?piae Frollo, the alga Palaeodasycladus ?mediterraneus (Pia), and the disputed alga Thaumatoporella ?parvovesiculifera (Raineri). The foraminifera compare most closely with poorly-known taxa from Italy, Spain and Morocco, and are consistent with an Early Jurassic (Sinemurian) age for the upper part of the &62;460-m-thick Gibraltar Limestone. Most are textulariids and more primitive than species well known from the later Early Jurassic (Pliensbachian) of the Mediterranean region, especially Morocco and Italy. The biota as a whole is characteristic of inner carbonate platform environments widespread along the rifted western margins of the Early Jurassic Tethys, notably those recorded from Morocco, Italy and Greece as well as southern Spain.

Early Jurassic benthic foraminiferal diversification and biozones in shallow-marine carbonates of western Tethys

Low-latitude carbonate platforms dominated the southern and northern margins and microplates of western Tethys during the Early Jurassic. However, these have proved difficult to date in the past partly due to a lack of study but also a perception of low biotic diversity following the Triassic-Jurassic extinction event. Detailed logging and sampling of seven continuously exposed sections of Lower Jurassic shallow-marine carbonates in Gibraltar, Morocco, Tunisia, Greece, Italy, and in Spain reveals the occurrence of 12 benthic foraminifera species. These taxa are described and illustrated, and include: one new speciesTextulariopsis sinemurensis, new records for the Early Jurassic, and new records for this region. Five new biozones for the late Hettangian to early Pliensbachian time interval are erected from the consecutive appearance of benthic foraminifera within these sections, from top to base:Lituosepta compressa, Lituosepta recoarensis, Everticyclammina praevirguliana, Siphovalvulina colomi andSiphovalvulina gibraltarensis. This has enabled the correlation of these sections for the first time from the northern and southern Tethys margins and from the Apuleian and Pelagonian microplates within Tethys. The foraminiferal occurrences indicate a similarity of associations from the southern and northern shallow carbonate shelves of Tethys, whilst reflecting the relative isolation of the Apuleian and Pelagonian microplates within Tethys. The foraminifera show a progressive diversification of forms through the late Hettangian to early Pliensbachian interval that is interpreted to reflect the evolutionary recovery and diversification of these biotas following the Triassic-Jurassic extinction event.