Ateleocystites? lansae sp. nov. is characterized by an elongate body with short spines that taper relatively rapidly. It has granular plate ornament adorally in addition to cuesta‐like ridges. Ateleocystites? lansae occurs commonly in a 5‐cm‐thick fine‐ to medium‐grained sandstone bed, which was rapidly emplaced and transported fossils from shallower water, within the Upper Ordovician (Katian), Slade and Redhill Beds along the A477 road and in the new quarry above The Old Mill Café, Tenby Road (now C3236), west of Llanddowror, Carmarthenshire. Other specimens are known from Sholeshook, Pembrokeshire. On the convex surface, the Welsh species differs from A. guttenbergensis Kolata and Jollie in having a larger central ‘placocystitid’ plate (C17) in contact with six, not five other plates. In addition, the marginal plates are scarcely visible on the convex surface. Plating on the planar surface agrees well with that of both A. guttenbergensis and the type species, A. huxleyi Billings. The presence of articulated appendages and spines and the lack of sediment fill in the bodies suggest that the new specimens were alive when buried. Ateleocystites? lansae probably lived largely buried in the sediment with the convex surface below and moved with the appendage in front. Copyright © 2015 John Wiley & Sons, Ltd.
Subduction of Bangong Suture Ocean and collision between the Lhasa and Qiangtang blocks were keys to better understand the development of central Tibet. However, the initiation and closure timing, and nature and structure of the Bangong suture are still poorly constrained. Mesozoic intrusions are widely distributed in central Tibet. Petrology, geochronology and geochemistry of the Renacuo pluton and their microgranular enclaves in the Gaize area to the north of the Bangong–Nujiang suture zone, south of the Longmu Co–Shuanghu suture zone, are used to constrain the tectonic history of the Bangong suture. Results of our SHRIMP U–Pb dating of the zircons are as follows: quartz diorite is 139 ± 4 Ma, MSWD = 1.6; the microgranular enclave is 147.3 ± 3.3 Ma, MSWD = 0.45. The evolutionary trend of the major elements, trace elements and rare earth elements of the microgranular enclaves and the host rocks are almost similar, suggesting that the enclaves and the host rocks may have had the same source. They most likely originated from magma mixing between mantle‐derived and crust‐derived melts. On the basis of our mapping and geochronologic studies, we suggest that the formation of the Renacuo pluton is consistent with previously suggested northward subduction of the Bangong Suture Ocean, which occurred in the Late Jurassic–Early Cretaceous. Copyright © 2015 John Wiley & Sons, Ltd.
…and keeps surviving them barely scathed. Chile has this year been rocked by its 3rd Great earthquake this century–its 14th if you include the last. Though the earthquake’s magnitude and the resulting Pacific-wide tsunami earned it headlines, it was a very mild earthquake in the global scheme of seismic impacts. This has a bit to do with the nature of offshore, subduction zone earthquakes, and a LOT to do with …
The first fossil echinoids are recorded from the Cayman Islands. A regular echinoid, Arbacia? sp., the spatangoids Brissus sp. cf. B. oblongus Wright and Schizaster sp. cf. S. americanus (Clark), and the clypeasteroid Clypeaster sp. are from the Middle Miocene Cayman Formation. Test fragments of the mellitid clypeasteroid, Leodia sexiesperforata (Leske), are from the Late Pleistocene Ironshore Formation. Miocene echinoids are preserved as (mainly internal) moulds; hence, all species are left in open nomenclature because of uncertainties regarding test architecture. All Miocene taxa are recorded from single specimens apart from the 27 assigned to Brissus. Schizaster sp. cf. S. americanus (Clark) is compared to a species from the Oligocene of the south‐east USA. Brissus sp. cf. B. oblongus is close in gross morphology to a taxon from the Miocene of Malta. Leodia sexiesperforata is identified from fragments with confidence, being the only extant Antillean sand dollar with elongate ambulacral petals that is limited to carbonate substrates. The Miocene echinoids of Grand Cayman, although of limited diversity, are mainly comprised of genera common in comparable mid‐Cenozoic carbonate environments. Copyright © 2015 John Wiley & Sons, Ltd.