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O. Renz

Bio: O. Renz is an academic researcher from Naturhistorisches Museum. The author has contributed to research in topics: Ophiolite & Parkinsonia (ammonite). The author has an hindex of 1, co-authored 1 publications receiving 50 citations.

Papers
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Journal ArticleDOI
TL;DR: Ammonites from the pillow basalt associations of the Siquisique ophiolites located in west-central Venezuela indicate a minimum Bajocian to early Bathonian age for emplacement of the complex.
Abstract: Ammonites from the pillow basalt associations of the Siquisique ophiolites located in west-central Venezuela indicate a minimum Bajocian to early Bathonian age for emplacement of the complex. The ammonites have been identified as ? Stephanoceras ( Skirroceras ) cf. macrum (Quenstedt), ? Emileia ex gr. multiformis (Gottsche) et quenstedti Westermann, and ? Parkinsonia sp. This association of cosmopolitan Pacific and Tethyan elements aids in the location of the western end of the Middle Jurassic seaway set between the Tethys and the Pacific Oceans (Hispanic Corridor). The apparent age of the ammonites indicates that some of the Siquisique sediments, pillow basalts, and serpentines are the oceanic remnants of an arrested early phase of rifting between North and South America.

52 citations


Cited by
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01 Jan 1999
TL;DR: In this paper, the authors present a series of detailed paleogeographical analyses of the Caribbean region, beginning with the opening of the Atlantic basin in the Middle Jurassic and running to the end of the Middle Miocene.
Abstract: "This paper presents a series of detailed paleogeographical analyses of the Caribbean region, beginning with the opening of the Caribbean basin in the Middle Jurassic and running to the end of the Middle Miocene. Three intervals within the Cenozoic are given special treatment: Eocene-Oligocene transition (35-33 Ma), Late Oligocene (27-25 Ma), and early Middle Miocene (16-14 Ma). While land mammals and other terrestrial vertebrates may have occupied landmasses in the Caribbean basin at any time, according to the interpretation presented here the existing Greater Antillean islands, as islands, are no older than Middle Eocene. Earlier islands must have existed, but it is not likely that they remained as such (i.e., as subaerial entities) due to repeated transgressions, subsidence, and (not incidentally) the K/T bolide impact and associated mega-tsunamis. Accordingly, we infer that the on-island lineages forming the existing (i.e., Quaternary) Antillean fauna must all be younger than Middle Eocene. The fossil record, although still very poor, is consistent with the observation that most land mammals lineages entered the Greater Antilles around the Eocene-Oligocene transition. Western Laurasia (North America) and western Gondwana (South America) were physically connected as continental areas until the mid-Jurassic, ca. 170 Ma. Terrestrial connections between these continental areas since then can only have occurred via landbridges. In the Cretaceous, three major uplift events, recorded as regional unconformities, may have produced intercontinental landbridges involving the Cretaceous Antillean island arc. The Late Campanian/Early Maastrichtian uplift event is the one most likely to have resulted in a landbridge, as it would have been coeval with uplift of the dying Cretaceous arc. However, evidence is too limited for any certainty on this point. The existing landbridge (Panamanian Isthmus) was completed in the Pliocene; evidence for a precursor bridge late in the Middle Miocene is ambiguous. We marshal extensive geological evidence to show that, during the Eocene-Oligocene transition, the developing northern Greater Antilles and northwestern South America were briefly connected by a "landspan" (i.e., a subaerial connection between a continent and one or more offshelf islands) centered on the emergent Aves Ridge. This structure (Greater Antilles + Aves Ridge) is dubbed GAARlandia. The massive uplift event that apparently permitted these connections was spent by 32 Ma; a general subsidence followed, ending the GAARlandia landspan phase. Thereafter, Caribbean neotectonism resulted in the subdivision of existing land areas. The GAARlandia hypothesis has great significance for understanding the history of the Antillean biota. Typically, the historical biogeography of the Greater Antilles is discussed in terms of whether the fauna was largely shaped by strict dispersal or strict continent-island vicariance. The GAARlandia hypothesis involves elements of both. Continent-island vicariance sensu Rosen appears to be excludable for any time period since the mid-Jurassic. Even if vicariance occurred at that time, its relevance for understanding the origin of the modern Antillean biota is minimal. Hedges and co-workers have strongly espoused over-water dispersal as the major and perhaps only method of vertebrate faunal formation in the Caribbean region. However, surface-current dispersal of propagules is inadequate as an explanation of observed distribution patterns of terrestrial faunas in the Greater Antilles. Even though there is a general tendency for Caribbean surface currents to flow northward with respect to the South American coastline, experimental evidence indicates that the final depositional sites of passively floating objects is highly unpredictable. Crucially, prior to the Pliocene, regional paleoceanography was such that current-flow patterns from major rivers would have delivered South American waifs to the Central American coast, not to the Greater or Lesser Antilles. Since at least three (capromyid rodents, pitheciine primates, and megalonychid sloths) and possibly four (nesophontid insectivores) lineages of Antillean mammals were already on one or more of the Greater Antilles by the Early Miocene, Hedges' inference as to the primacy of over-water dispersal appears to be at odds with the facts. By contrast, the landspan model is consistent with most aspects of Antillean land-mammal biogeography as currently known; whether it is consistent with the biogeography of other groups remains to be seen"--P. 3.

569 citations

Journal ArticleDOI
TL;DR: The evolution of the former Tethys ocean in terms of successive positions of the involved plates, their boundaries, and the oceanic and continental elements they bore is described in this paper.

400 citations

Journal ArticleDOI
TL;DR: The formation of a Mesozoic marine seaway between western Tethys and the eastern Pacific, across west-central Pangea, has been postulated for the Early Jurassic (Hettangian-Pliensbachian) according to biogeographic considerations, but supporting stratigraphic data are lacking as mentioned in this paper.
Abstract: Since the latest Triassic, the Caribbean started to form as a system of rift valleys within westcentral Pangea, later evolving into a mediterranean sea where distinct volcanic and non-volcanic islands evolved. Since its very early formation, this sea has been playing an important role controlling the historical patterns of ocean water circulation, moderating the world climate, and determining the possibilities of biotic exchange of the surrounding terrestrial and marine ecosystems. The formation of a Mesozoic marine seaway between western Tethys and the eastern Pacific, across west-central Pangea, has been postulated for the Early Jurassic (Hettangian-Pliensbachian) according to biogeographic considerations, but supporting stratigraphic data are lacking. Probably since the Bathonian but certainly since the Oxfordian, the stratigraphic record indicates that this connection was fully functional and the Circum-Tropical marine current was active. Overland dispersal between western Laurasia (North America) and...

323 citations

Book ChapterDOI
01 Jan 2003
TL;DR: In this paper, an integrated synthesis and interpretation of the tectonic assembly of the entire Northern Andean Block (the Andes of Ecuador, Colombia, and Venezuela) is presented based on the identification and characterization of more than 30 distinct lithotectonic and morphostructural units and their bounding suture and fault systems.
Abstract: Based primarily on geologic field observations as recorded by numerous geoscientists over the last three decades, backed by more recent geochemical, seismic, gravity, magnetic, tomographic, and satellite-based techniques, an integrated synthesis and interpretation of the tectonic assembly of the entire Northern Andean Block (the Andes of Ecuador, Colombia, and Venezuela) is presented. Tectonic reconstruction is based on the identification and characterization of more than 30 distinct lithotectonic and morphostructural units (including terranes, terrane assemblages, physiographic domains, etc.) and their bounding suture and fault systems, which, based on geologic, geophysical, and dynamo-tectonic considerations, define four distinct tectonic realms representing the entire Northern Andean region. These include the Guiana Shield Realm (GSR), the Maracaibo subplate Realm (MSP), the Central Continental subplate Realm (CCSP), and the Western Tectonic Realm (WTR). The GSR provided the backstop for the progressive, accretionary continental growth of northwestern South America in the middle–late Proterozoic, in the middle Paleozoic, and finally during the Mesozoic-Cenozoic Northern Andean orogeny. Middle Cretaceous through Miocene time slices illustrate how, beginning in the Aptian, the sequential dextral-oblique accretion of the allochthonous oceanic WTR along the Pacific margin acted simultaneously with the northwest migration of the MSP (a detached segment of the Guiana Shield) into and over the Caribbean plate, exerting enormous transpression upon the CCSP trapped between them. Each tectonic realm contributed distinct tectonic mechanisms during Northern Andean cause and response orogenesis, and each realm records a unique internal deformational style, which in large part provides the basis for realm definition. Additionally, based on lithologic, geochemical, and paleomagnetic data and paleogeographic reconstructions, the intimate and complementary Mesozoic-Cenozoic history of the Northern Andean Block and the Caribbean plate are recognized. The migratory path of the Caribbean plate along the western and northern margin of the South American craton, as recorded by the accretionary history of the allochthonous WTR, has been instrumental in the modern-day configuration of the Northern Andean Block. Throughout this paper, the importance and contribution of underlying Proterozoic through middle Mesozoic geostructural elements in the development of Mesozoic-Cenozoic Northern Andean orogeny-phase tectonic configuration (structural style, uplift mechanisms, basin development, magmatism, etc.) are stressed. Additionally, the complex reality of Northern Andean Block assembly is contrasted with classical Central Andean Cordilleran-type orogenic models, and numerous differences are illustrated that render the application of typical Cordilleran-type models unacceptable. These differences are exemplified by the highly oblique collision/accretion/subduction tectonics of allochthonous oceanic terranes in the WTR, the detachment, migration and plis de fond–style of deformation in the MSP and the unique, transpressive pop-up of the Eastern Cordillera in the CCSP, all of which have no geologic analog in the Central Andes.

271 citations

Journal ArticleDOI
TL;DR: Cuba is considered to consist of two separate geological units: a foldbelt and a neo-autochthon as mentioned in this paper. But this is not the case in most of the existing works.
Abstract: Cuba is considered here to consist of two separate geological units: a foldbelt and a neo-autochthon.

170 citations