The Sima de los Huesos (Burgos,northern Spain): palaeoenvironment and habitats of Homo heidelbergensis during the Middle Pleistocene     

Nuria García  Juan Luis Arsuaga 《Quaternary Science Reviews》2011,30(11-12):1413-1419

Interpreting how environmental dynamics respond to global climate change and how this has affected human evolution and dispersal is an on-going topic of debate. During the early Middle Pleistocene (～0.6–0.4 Ma), as compared to earlier, environmental conditions were relatively more stable, with longer climatic cycles alternating between open and forested landscapes. During this interval, humans spread successfully providing an important number of fossil sites where fossils or tools are reported. The Atapuerca-Sima de los Huesos (Burgos, northern Spain) site (Atapuerca-SH) is one of the earliest localities with hominin evidence in the European Middle Pleistocene, with the most important accumulation of Homo heidelbergensis so far. We have analyzed the abundant faunal record from Sima de los Huesos, which is mainly comprised of carnivores, in order to approach an interpretation of the palaeoenvironmental circumstances where these hominids inhabited within the Sierra. Other sites from Sierra de Atapuerca referred to the same Faunal Unit (FU 6), are roughly contemporaneous, and include important ungulates, which are here analyzed with Atapuerca-SH. Additional information provided by isotopic analysis helps elucidate the ancient ecology of taxa present in Sima de los Huesos allowing for an accurate portrayal of the setting in which humans lived. The timing of the spread of Homo heidelbergensis is dominated by a relative climatic and environmental stability and points to a landscape dominated by savannah-like open woodland.  相似文献   

Barringer,Back to the Future: Airborne Geochemistry and Many Related Topics,Peter Bradshaw,Association of Applied Geochemists,Nepean, ON,Canada (2015), 159 pp. Hard Cover book,including shipping US$ 68.00. Soft Cover book,including shipping US$ 58.00. ISBN: 978-0-09691014-5-1. Available from: www.appliedgeochemists.org     

《Ore Geology Reviews》2016

  相似文献   

Asymmetric continental deformation during South Atlantic rifting along southern Brazil and Namibia     

《Gondwana Research》2017

Plate restoration of South America and Africa to their pre-breakup position faces the problem of gaps and overlaps between the continents, an issue commonly solved with implementing intra-plate deformation zones within South America. One of these zones is often positioned at the latitude of SE/S Brazil. However, geological evidence for the existence of a distinct zone in this region is lacking, which is why it remains controversial and is not included in all modeling studies. In order to solve this problem we present a study of multiple geological aspects of both parts of the margin, SE/S Brazil and its conjugate part NW Namibia at the time of continental breakup. Our study highlights pronounced differences between these regions with respect to Paraná-Etendeka lava distribution, magmatic dyke emplacement, basement reactivation, and fault patterns. In Namibia, faults and dykes reactivated the rift-parallel Neoproterozoic basement structure, whereas such reactivation was scarce in SE/S Brazil. Instead, most dykes, accompanied by small-scale grabens, are oriented margin-perpendicular along the margin from northern Uruguay to São Paulo. We propose that these differences are rooted in large-scale plate movement and suggest a clockwise rotation of southern South America away from a stable northern South America and Africa, in a similar way as proposed by others for a Patagonian continental section just prior to South Atlantic rifting. This rotation would produce margin-parallel extension in SE/S Brazil forming margin-perpendicular pathways for lava extrusion and leading to the asymmetric distribution of the Paraná-Etendeka lavas. NW Namibia instead remained relatively stable and was only influenced by extension due to rifting, hot spot activity, and mantle upwelling. Our study argues for significant margin-parallel extension in SE/S Brazil, however not confined to a single distinct deformation zone, but distributed across ~ 1000 km along the margin.  相似文献   

The Mesoproterozoic Abra polymetallic sedimentary rock-hosted mineral deposit,Edmund Basin,Western Australia     

《Ore Geology Reviews》2016

Abra is a blind, sedimentary rock-hosted polymetallic Fe–Pb–Zn–Ba–Cu ± Au ± Ag ± Bi ± W deposit, discovered in 1981, located within the easterly trending Jillawarra rift sub-basin of the Mesoproterozoic Edmund Basin, Capricorn Orogen, Western Australia. The Edmund Basin contains a 4–10 km thick succession of siltstone, sandstone, dolomitic siltstone, and stromatolitic dolomite. The age of the Edmund Group is between 1.66 and 1.46 Ga. The Abra polymetallic deposit is hosted in siltstone, dolostone, sandstone and conglomerate of the Irregully and Kiangi Creek Formations, but the mineralised zones do not extend above an erosion surface marking the change from fluvial to marine facies in the lower part of the Kiangi Creek Formation. The Abra deposit is characterised by a funnel-shaped brecciated zone, interpreted as a feeder pipe, overlain by stratiform–stratabound mineralisation. The stratiform–stratabound mineralisation includes a Red Zone and an underlying Black Zone. The Red Zone is characterised by banded jaspilite, hematite, galena, pyrite, quartz, barite, and siderite. The jaspilite and hematite cause the predominant red colouration. The Black Zone consists of veins and rhythmically banded sulphides, laminated and/or brecciated hematite, magnetite, Fe-rich carbonate and scheelite. In both zones, laminations and bands of sulphide minerals, Fe oxides, barite and quartz commonly exhibit colloform textures. The feeder pipe (Stringer Zone) merges with Black Zone and consists of a stockwork of Fe-carbonate-quartz, barite, pyrite, magnetite and chalcopyrite, exhibiting fluidised and/or jigsaw textures.The Abra mineral system is characterised by several overprinting phases of hydrothermal activity, from several stages of brecciation and fluidisation, barite and sulphide veining to barren low-temperature chalcedonic (epithermal regime) veining. Hydrothermal alteration minerals include multi-stage quartz, chlorite, prehnite, Fe-rich carbonate and albite. Albite (Na metasomatism) is an early alteration phase, whereas Fe-rich carbonate is a late phase. Fluid inclusion studies indicate that the ore fluids had temperatures ranging from 162 to 250 °C, with salinities ranging from 5.8 to about 20 wt.% NaCl. In the course of our studies, microthermometric and Raman microprobe analyses were performed on fluid inclusions in carbonate, quartz and barite grains. Fluid inclusions in quartz show homogenisation temperatures ranging from 150 to 170 °C with calculated salinities of between 3.7 and 13.8 wt.% NaCl.The sulphur isotopic system shows δ³⁴S values ranging from 19.4 to 26.6‰ for sulphides and from 37.4 to 41.9‰ for barite (Vogt and Stumpfl, 1987, Austen, 2007). Sulphur isotope thermometry between sulphides and sulphide–barite pairs yields values ranging from 219 to 336 °C (Austen, 2007).Galena samples were analysed for Pb isotope ratios, which have been compared with previous Pb isotopic data. The new Pb isotope systematics show model ages of 1650–1628 Ma, consistent with the formation of the host Edmund Basin.Re–Os dating of euhedral pyrite from the Black Zone yielded an age of ~ 1255 Ma. This age corresponds to the 1320–1170 Ma Mutherbukin tectonic event in the Gascoyne Complex. This event is manifested primarily along a WNW-trending structural corridor of amphibolite facies rocks, about 250 km to the northwest of the Abra area. It is possible that the Re–Os age represents a younger re-activation event of an earlier SEDEX style system with a possible age range of 1640–1590 Ma.A genetic model for Abra is proposed based on the above data. The model involves two end-members ore-forming stages: the first is the formation of the SEDEX style mineral systems, followed by a second multi-phase stage during which there was repeated re-working of the mineral system, guided by seismic activity along major regional faults.  相似文献   

Partial least squares-discriminant analysis of trace element compositions of magnetite from various VMS deposit subtypes: Application to mineral exploration     

《Ore Geology Reviews》2016

The petrography and mineral chemistry of magnetite from fifteen volcanogenic massive sulfide (VMS) deposits in Canada, and the Lasail VMS deposit in Oman, as well as from two VMS-associated banded iron formations (BIF), Austin Brook (New Brunswick, Canada) and Izok Lake (Nunavut, Canada), were investigated using optical microscopy, electron probe micro-analyzer (EPMA), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The method of robust estimation for compositional data (robCompositions) was applied to investigate geochemical censored data. Among thirty-seven elements analyzed by EPMA and/or LA-ICP-MS in magnetite from the studied deposits/bedrock lithologies, only the results for Si, Ca, Zr, Al, Mg, Ti, Zn, Co and Ni contain < 40% censored values, and thus could be imputed using robCompositions. Imputed censored data were transformed using centered log-ratios to overcome the closure effect on compositional data. Transformed data were classified by partial least squares-discriminant analysis (PLS-DA) to identify different compositional characteristics of magnetite from VMS deposits and BIFs. The integration of petrography and mineral chemistry identifies three types of magnetite in VMS settings: magmatic, hydrothermal, and metamorphic. Magmatic magnetite in VMS deposit host bedrocks is characterized by ilmenite exsolution and may be overprinted by metamorphism. Some VMS deposits contain hydrothermal magnetite, which is intergrown with sulfides, and shows a metamorphic overprint as it is partly replaced by common metamorphic minerals including chlorite, sericite, anthophyllite, and/or actinolite, whereas the majority of the deposits are characterized by metamorphic magnetite formed by replacing pre-existing sulfides and/or silicates, and is intergrown with metamorphic minerals. Among VMS deposits of the Noranda mining district, the West Ansil deposit is characterized by hydrothermal-metamorphic magnetite zoned by inclusion-free cores and Si- and Mg-rich rims. Magnetite from the studied VMS-associated BIFs is also metamorphic in origin. Aluminum, Ti and Zn contents of magnetite can separate BIF from the other mineralized and un-mineralized bedrock lithologies in the studied VMS settings.PLS-DA shows that variable compositions of magnetite slightly discriminate different studied deposits/bedrock lithologies. The geochemical observations suggest that the variation in magnetite chemistry from different VMS settings might be sourced from differences in: 1) the composition and temperature of parental magmas or hydrothermal fluids, 2) the composition of host bedrocks, 3) the composition of co-forming minerals, and 4) oxygen fugacity. PLS-DA distinguishes magnetite compositions from the studied VMS deposits and BIFs from that of the other ore deposit types including Ni–Cu, porphyry Cu-Mo-Au, iron oxide-copper- gold, iron oxide-apatite, and the Bayan Obo REE-Fe-Nb deposit. Magnetite from the VMS settings on average contains lower concentrations of Si, Zr, Al, Mg, Ti, Zn, Co and Ni relative to that from the other mineral deposit types. PLS-DA of magnetite data from VMS deposits and BIFs of the Bathurst mining camp as well as PLS-DA of magnetite compositions from various mineral deposit types yield discrimination models for application to mineral exploration for VMS deposits using indicator minerals in Quaternary lithified sedimentary rocks.  相似文献   

Apatite geochemistry of the Taihe layered intrusion,SW China: Implications for the magmatic differentiation and the origin of apatite-rich Fe-Ti oxide ores     

《Ore Geology Reviews》2016

The Taihe intrusion is one of the layered intrusions situated in the central zone of the Emeishan Large Igneous Province (ELIP), SW China. The cyclic units in the Middle Zone of the intrusion are composed of apatite-magnetite clinopyroxenite at the base and gabbro at the top. The apatite-rich oxide ores contain 6–12 modal% apatite and 20–50 modal% Fe-Ti oxides evidently distinguished from the coeval intrusions in which apatite-rich rocks are poor in Fe-Ti oxides. Most of apatites of the Taihe Middle and Upper Zones are fluorapatite, although four samples show slightly high Cl content in apatite suggesting that they crystallize from a hydrous parental magma. Compared to the apatite from the gabbro of the Panzhihua intrusion, situated 100 km to the south of the Taihe intrusion, the apatite of the Taihe rocks is richer in Sr and depleted in HREE relative to LREE. The calculated magma in equilibrium with apatite of the Taihe Middle and Upper Zones also shows weakly negative Sr anomalies in primitive mantle normalized trace element diagrams. These features indicate that the apatite of the Taihe Middle and Upper Zones crystallizes after clinopyroxene and before plagioclase. The apatite of the Taihe Middle and Upper Zones shows weakly negative Eu anomalies suggesting a high oxygen fugacity condition. The high iron and titanium contents in the oxidizing magma result in crystallization of Fe-Ti oxides. Crystallization of abundant Fe-Ti oxides and clinopyroxenes lowers the solubility of phosphorus and elevates SiO₂ concentration in the magma triggering the saturation of apatite. The positive correlations of Sr, V, total REE contents and Ce/Yb ratio in apatite with cumulus clinopyroxene demonstrate approximately compositional equilibrium between these phases suggesting they crystallized from the same ferrobasaltic magma. Early crystallization and accumulation of Fe-Ti oxide together with apatite produced the apatite-rich oxide ores at the base of the cyclic units of the Taihe Middle Zone.  相似文献   

Saurischian track assemblages from the Lower Cretaceous Shenhuangshan Formation in the Yuanma Basin,Southern China     

《Cretaceous Research》2016

Cretaceous dinosaur tracks from Hunan Province are historically significant as the basis for three ichnotaxa: Xiangxipus chenxiensis, Xiangxipus youngi, and Hunanpus jiuquwanensis all representing theropodan tracks, described from a single site in 1982. Although the type locality has since been destroyed, the type specimen and replicas remained available for restudy in 2006, when paratype Hunanpus tracks and sauropod footprints were described from a second, nearby locality. Material from both localities is here re-described in detail. It is proposed that while Xiangxipus chenxiensis can be regarded as a distinct ichnospecies, probably representing an ornithomimid trackmaker, Xiangxipus youngi cannot be accommodated in the same ichnogenus. We consider it similar to the ichnogenus Wupus from the Lower Cretaceous of Sichuan Province, and therefore of possible avian affinity. We also find no justification for regarding Hunanpus jiuquwanensis as generically distinct from the widespread ichnogenus Grallator, and therefore rename it Grallator jiuquwanensis comb. nov. The Hunan track record is generally consistent with the sparse record of theropod skeletal remains in the province, but adds evidence of sauropods that was previously lacking.  相似文献   

Small scale scrapes suggest avian display behavior by diminutive Cretaceous theropods     

《Cretaceous Research》2016

A set of about 25 diminutive sub-parallel scrapes in the Cretaceous Haman Formation of South Korea fit the morphology of the small theropod track Minisauripus which is also known from this formation. The scrapes are interpreted as evidence of display behavior, and suggest that the trace maker was an adult engaged in avian-like courtship behavior. Although avian theropods are also known from this formation, the scrapes are inconsistent with their foot morphology. Although large theropod scrapes have been interpreted as evidence of display behavior they are only known from North America. Thus, the scrapes described here are the first reported from Asia, and the first interpreted as evidence of display behavior in such a diminutive species.  相似文献   

A new species of the Late Cretaceous ‘sail-finned’ bony fish,Pentanogmius (Actinopterygii: Tselfatiiformes), from Texas,USA     

《Cretaceous Research》2016

Pentanogmius Taverne (Actinopterygii: Tselfatiiformes) is a Late Cretaceous bony fish. Here, the diagnosis for the genus is emended and a new species, P. fritschi sp. nov., described. The new species is based on a nearly complete skeleton from the Britton Formation (upper Cenomanian–lower Turonian) of the Eagle Ford Shale in Dallas County, Texas, USA. The skeleton measures about 1.7 m in total length and represents the sole Cenomanian–Turonian example of Pentanogmius in North America. The most peculiar aspect of this new species is the morphology of the dorsal fin in which its anterior one-third is elongate to form a ‘hook-shaped sail.’ Pentanogmius fritschi sp. nov. was likely an active swimmer in open ocean environments that possibly fed opportunistically on a variety of relatively small pelagic fishes and invertebrates. The present stratigraphic record and anatomical evidence indicate the following phylogenetic hypothesis among the three North American Pentanogmius species: [P. fritschi sp. nov. [P. evolutus + P. crieleyi]].  相似文献   

Late Cenomanian environmental conditions at the submerged Tatric Ridge,Central Western Carpathians during the period preceding Oceanic Anoxic Event 2 – A palaeontological and isotopic approach     

《Cretaceous Research》2016

Micropalaeontological and isotopic studies of the upper Cenomanian turbiditic/hemipelagic sediments from the High-Tatric unit (Central Western Carpathians; Polish part of the Tatra Mountains) has been undertaken to characterize the sedimentary conditions in the Tatric basin, a part of the Western Tethys, related to the interval preceding the late Cenomanian oceanic anoxic event (OAE2). The deposition of these sediments, including organic-rich layers (TOC up to 0.7%), corresponds to the Rotalipora cushmani foraminiferal Zone. Microfacial, foraminiferal and palynological analyses show that the sea floor was located at upper bathyal depths and the water column was poorly oxygenated. The intrabasinal carbonate material indicates moderate primary productivity with rare periods of upwellings. The scarcity of marine fossils in redeposited material and features of carbonate lithoclasts suggest very low productivity in the nearshore surface water, most probably due to a low-density hyposaline cap as surface runoff from the southern margin of the basin. The carbon isotopic study documents the negative values of δ¹³C_carb in the whole section as an effect of transfer of isotopically light carbon sourced from various sources. Such negative values of δ¹³C_carb are characteristic of the upper Cenomanian sediments, deposited in relatively shallow water basins, characterized by input of terrestrial organic matter and/or carbonate particles known from the Western Interior sections, the Atlantic coastal plain, the northwestern African margin, the eastern margin of the Apulian Platform and shelf sediments in the NW Europe and Tethyan Himalayas. Most probably, all of these events could be related to the global sea level fluctuations that occurred ca. 95.5–94.5 Ma comparing with the Haq (2014) eustatic curve.  相似文献