Comment on 'Restoration of Cenozoic deformation in Asia and the size of Greater India' by D. J. J. van Hinsbergen et al.

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Upper Paleocene radiolarians from DSDP Sites 549 and 550, Goban Spur, NE Atlantic

Upper Paleocene-lower Eocene sequences of mainly pelagic sediments in DSDP Sites 549 and 550 of Goban Spur, NE Atlantic, representing time periods of 10 and 6. m.y. respectively, were examined to investigate the biotic response of radiolarians to the PETM. The preservation of radiolarians in the lower Eocene sequences for both sites is poor. Upper Paleocene radiolarian assemblages, representing a time interval of ~59-56. Ma at Site 549 and a much shorter period at Site 550, are generally moderately well-preserved. Fifty-four species were identified. Four species occur significantly earlier in the middle high latitude NE Atlantic than in New Zealand, where the sudden appearance during the PETM has been taken as evidence of global pole-ward migration of warm-water radiolarians. Available model shows that the Goban Spur area should belong to the subpolar surface ocean gyre in the early Paleogene. Thus, our investigation questions the validity of the previously used index species of subtropical warm water masses. High-latitude offshore sections across the P/E boundary with well preserved radiolarians are needed to test the hypothesis of pole-ward migration of warm-water radiolarians during this geologically transient global warming period. © 2011 Elsevier Ltd and Nanjing Institute of Geology and Palaeontology, CAS.postprin

Reply to comment by Eduardo Garzanti on "When and where did India and Asia collide"

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Lowermost Ordovician (basal Tremadoc) radiolarians from the Little Port Complex, western Newfoundland

Lowermost Ordovician (basal Tremadoc) cherts from the Little Port Complex, western Newfoundland, contain a distinctive, moderately well-preserved, radiolarian assemblage. The fauna differs from those reported from the Arenig, suggesting that somes of the earliest radiolarian forms may have biostratigraphic potential. The abundance of radiolarians in chert and the ease with which they can be extracted suggest that they are a potentially valuable tool for use in investigation of the timing and development of early Palaeozoic orogenic systems. A previously undescribed radiolarian Beothuka terranova sp. nov., belonging to a new genus Beothuka gen. nov. and of uncertain higher-level affinity is formalized herein.published_or_final_versio

Inter-shell casts of entactiniid radiolarians from the Devonian of SW China

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The sedimentary geology, palaeoenvironments and ichnocoenoses of the Lower Devonian Horlick Formation, Ohio Range, Antarctica

Six ichnocoenoses in the clastic Devonian Horlick Formation (max. 56 m) confirm the nearshore marine character of eight of the nine lithofacies present. A basal sand sheet overlies a weathered granitic land surface (Kukri Erosion Surface) on Cambro - Ordovician granitoids. The level nature of this surface and the way it cuts across weathering profiles, suggests that the surface had been modified by marine processes prior to deposition. The basal sand sheet (Cross-bedded Sand sheet Lithofacies) contains tidal bundles, and at its top, abundant Monocraterion (Monocraterion Ichnocoenosis). The second sand sheet (Pleurothyrella Lithofacies) is heavily burrowed and shows alternating periods of sedimentation, burrowing, and erosion below wave base as the sea deepened (Catenarichnus Ichnocoenosis). With increasing transgression, finer sediments were deposited (Laminated Mudstone and Feldspathic lithofacies) in an unstable pattern of coarse sandbars and finer troughs (Cruziana-Rusophycus and Arenicolites ichnocoenoses) crossed by active longshore marine channels (Poorly-sorted Lithofacies, Spirophyton Ichnoocoenosis). Short-lived but powerful storms produced thin shelly tempestites (Shell-bed Lithofacies), whereas sporadic, very thin phosphate rich beds (Phosphatic Lithofacies) may have resulted from marine transgressions across the basin. The deepest water is probably represented by sediments of the Spirifer Lithofacies (Rosselia Ichnocoenosis). The Schulthess Lithofacies is regarded as fluvial, deposited in the lower reaches of a river draining a land area that lay towards Marie Byrd Land. Channels in the basal sand sheet indicate movement to the southwest, but orientation became more variable higher in the sequence. Four new measured sections are figured. The relationship of the Ohio Range to the rest of Antarctica during the Devonian is suggested.published_or_final_versio

North Luzon and the Philippine Sea Plate motion model: Insights following paleomagnetic, structural, and age-dating investigations

Results of one of the most comprehensive paleomagnetic and supporting geological programs ever carried out in offshore SE Asia on North Luzon, northern Philippines, are reported. Six new results, based on 66 sites, are reported from a total collection of 243 individual sites. Declinations in the data subset are sometimes scattered, likely reflecting combinations of major plate and local rotations in both clockwise and counterclockwise directions, and thus have a somewhat limited value for tectonic modeling. The inclination data are, however, much more valuable and can be best explained if North Luzon traveled as part of the Philippine Sea Plate for most of its history, a scenario which is compatible with the known geology of the eastern Philippines and broader region. In the proposed model, for all of its Eocene-Pliocene history, North Luzon is placed on the western edge of the Philippine Sea Plate, effectively always just to the west of the site where the Benham Plateau formed ~40 Ma. The paleomagnetic data indicate a substantial northward migration of the area since the start of the Neogene, with an earlier interval stretching back to at least the mid-Early Cretaceous when this part of the plate occupied equatorial latitudes. Post-15 Ma motion of the plate has involved the indentation of the Palawan microcontinental block into the western side of the Philippine Archipelago. Deformations induced by this process offer the most likely explanation for the scattered declinations observed in North Luzon and areas a short distance to the south. Copyright 2007 by the American Geophysical Union.published_or_final_versio

Written records of historical tsunamis in the northeastern South China Sea - Challenges associated with developing a new integrated database

Comprehensive analysis of 15 previously published regional databases incorporating more than 100 sources leads to a newly revised historical tsunami database for the northeastern (NE) region of the South China Sea (SCS) including Taiwan. The validity of each reported historical tsunami event listed in our database is assessed by comparing and contrasting the information and descriptions provided in the other databases. All earlier databases suffer from errors associated with inaccuracies in translation between different languages, calendars and location names. The new database contains 205 records of "events" reported to have occurred between AD 1076 and 2009. We identify and investigate 58 recorded tsunami events in the region. The validity of each event is based on the consistency and accuracy of the reports along with the relative number of individual records for that event. Of the 58 events, 23 are regarded as "valid" (confirmed) events, three are "probable" events and six are "possible". Eighteen events are considered "doubtful" and eight events "invalid". The most destructive tsunami of the 23 valid events occurred in 1867 and affected Keelung, northern Taiwan, killing at least 100 people. Inaccuracies in the historical record aside, this new database highlights the occurrence and geographical extent of several large tsunamis in the NE SCS region and allows an elementary statistical analysis of annual recurrence intervals. Based on historical records from 1951-2009 the probability of a tsunami (from any source) affecting the region in any given year is relatively high (33.4%). However, the likelihood of a tsunami that has a wave height >1 m, and/or causes fatalities and damage to infrastructure occurring in the region in any given year is low (1-2%). This work indicates the need for further research using coastal stratigraphy and inundation modeling to help validate some of the historical accounts of tsunamis as well as adequately evaluate the recurrence intervals of tsunamis along the now heavily developed coastlines of the region. © Author(s) 2010.published_or_final_versio

Geochemistry and geobarometry of Eocene dykes intruding the Ladakh Batholith

We present further distinguishing characteristics among Eocene dykes found along the Southern margin of the Ladakh batholith (NW-India). Coupled evidence from field structures and Nd-Sr isotope data showed that there are two broad dyke provinces extending over 50 km: between Leh and Tunglung, an 'eastern', ENE-trending family with higher crustal assimilation; between Tunglung and Hemis Shugpachan, the ...postprin

Precise radiolarian age constraints on the timing of ophiolite generation and sedimentation in the Dazhuqu terrane, Yarlung-Tsangpo suture zone, Tibet

Well-preserved, abundant radiolarians provide high-precision biostratigraphic age constraints on the timing of the eruption of ophiolitic basalts exposed along the Yarlung-Tsangpo suture zone in southern Tibet. Dazhuqu terrane ophiolites were generated in an intra-oceanic supra-subduction zone setting within a relatively short (<10 Ma) interval from late Barremian to late Aptian. Accumulation of sediments upon the newly generated ophiolite initially occurred in a series of discrete rift-controlled sub-basins associated with various spreading centres. An increasing flux of arc-derived volcaniclastic sediment up-section indicates nearby volcanic are activity. The Dazhuqu terrane developed in an intra-oceanic setting within Tethys where it was isolated from any continental influence.published_or_final_versio