DOCSLIB.ORG

U-Pb Zircon Geochronology of Major Lithologic Units in the Eastern Himalaya: Implications for the Origin and Assembly of Himalayan Rocks

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
U-Pb Zircon Geochronology of Major Lithologic Units in the Eastern Himalaya: Implications for the Origin and Assembly of Himalayan Rocks U-Pb zircon geochronology of major lithologic units in the eastern Himalaya: Implications for the origin and assembly of Himalayan rocks A. Alexander G. Webb1,†, An Yin2, and Chandra S. Dubey3 1Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095, USA 3Department of Geology, Delhi University, Delhi-110007, India ABSTRACT The ca. 280–220 Ma detrital zircons of the Indian basement and cover sequences (Argand, Late Triassic strata are derived from an arc 1924; Heim and Gansser, 1939; Dewey and Models for the origin and deformation of developed along the northern margin of the Bird, 1970; Le Fort, 1975). Himalayan rocks are dependent upon geo- Lhasa terrane. Detritus from this arc was de- metric and age relationships between major posited on the northern margin of India dur- Assembling the Himalaya units. We present fi eld mapping and U-Pb ing India-Lhasa rifting. Along-strike hetero- dating of igneous and detrital zircons that es- geneity in Main Central thrust footwall Structural evidence provided the fi rst intima- tablish the lithostratigraphic architecture of chronostratigraphy is indicated by detrital tion that the kinematic evolution might have the eastern Himalaya, revealing that: (1) the zircon age spectrum differences from central involved complexities beyond thrust tectonics. South Tibet detachment along the Bhutan- western to far western Arunachal. Nonethe- Recognition of top-to-the-north shear structures China border is a top-to-the-north ductile less, the Late Proterozoic rocks in the Main along the gently north-dipping GHC-THS con- shear zone; (2) Late Triassic and Early Cre- Central thrust hanging wall and footwall in tact at the range crest (e.g., Caby et al., 1983; taceous sedimentary samples from the north- far western Arunachal can be correlated to Burg et al., 1984) quickly led to acceptance of a ern Indian margin show a similar age range each other, and to previously analyzed rocks new paradigm—that this contact was defi ned by of detrital zircons from ca. 3500 Ma to ca. in the South Tibet detachment hanging wall a top-to-the-north low-angle normal fault sys- 200 Ma, but the Late Triassic rocks are distin- to the west and in the Indian craton to the tem with tens or even hundreds of kilometers of guished by a signifi cant age cluster between south. These fi ndings are synthesized in a slip (e.g., Searle, 1986; Burchfi el et al., 1992). ca. 280 and ca. 220 Ma and a well-defi ned reconstruction showing Late Triassic India- This fault system is termed the South Tibet de- age peak at ca. 570 Ma, (3) an augen gneiss Lhasa rifting and Cenozoic eastern Hima- tachment. Current models for the assembly of in the South Tibet detachment shear zone layan construction via in situ thrusting of the Himalayan units focus on the emplacement in southeast Tibet has a Cambrian–Ordo- basement and cover sequences along the of the GHC along the South Tibet detachment vician crystallization age, (4) Main Central north Indian margin. and the Main Central thrust, which emplaced thrust hanging-wall paragneiss and footwall the GHC southward over the LHS. quartzites from the far western Arunachal INTRODUCTION The fi rst kinematic model proposed for this Himalaya share similar provenance and Late emplacement is wedge extrusion, in which the Proterozoic maximum depositional ages, and Simple questions of Himalayan geology— GHC extruded southward between the other (5) Main Central thrust footwall metagray- i.e., where does Himalayan material originate, two units as a northward-tapering wedge (Fig. wacke from the central western Arunachal and how was it assembled?—may have surpris- 2A; Burchfi el and Royden, 1985). Some recent Himalaya has a Paleoproterozoic maximum ingly complex answers. The geometric frame- workers associated these kinematics with criti- depositional age, indicated by a single promi- work of the Himalayan orogen was established cal taper–Coulomb wedge theory (e.g., Robin- nent age peak of ca. 1780 Ma. Recent work by Heim and Gansser (1939), who divided it son et al., 2006; Kohn, 2008; Zhang et al., 2011), in the eastern Himalaya demonstrates that into a generally north-dipping stack of three which suggests that normal faulting may occur in the early-middle Miocene, the Himalayan units separated from foreland detritus to the during collapse of overthickened thrust wedges crystalline core here was emplaced south- south and Asian plate rocks to the north. These (e.g., Davis et al., 1983; Dahlen, 1990). In the ward between two subhorizontal shear zones units are now termed the Lesser Himalayan Se- second kinematic model, channel fl ow–focused that merge to the south. A proposed subse- quence (LHS, at the base), the Greater Himala- denudation, the GHC represents partially mol- quent (middle Miocene) brittle low-angle yan Crystalline complex (GHC, in the middle), ten lower to middle crust that tunneled south- normal fault accomplishing exhumation of and the Tethyan Himalayan Sequence (THS, at ward during the Eocene–Oligocene (Fig. 2B), a these rocks along the range crest can be pre- the top) (Fig. 1; e.g., Yin, 2006). Early models process driven by the lateral pressure gradient cluded because new and existing mapping for the origin and assembly of these units were created by the gravitational potential difference demonstrates only a ductile shear zone here. straightforward, suggesting that as the southern between the Tibetan Plateau and its margins front of the India-Asia collision, the Himalayan (e.g., Beaumont et al., 2001, 2004; Godin et al., †E-mail: [email protected] orogen was generated via in situ thrusting of 2006). Subsequently, this channel was exhumed GSA Bulletin; March/April 2013; v. 125; no. 3/4; p. 499–522; doi: 10.1130/B30626.1; 12 fi gures; 2 tables; Data Repository item 2012341. For permission to copy, contact [email protected] 499 © 2013 Geological Society of America Webb et al. 7070°EoE 8080°EoE 9090°EoE N 3030°NoN China Figure 4A India Bhutan 30°N Myanmar Pakistan India Bangladesh (Burma) Tethyan Himalayan Sequence: Quaternary Main Central thrust (MCT) < Precambrian - Cambrian Late Cretaceous - Tertiary < Ordovician - Mesozoic South Tibet detachment (STD) (includes Pulchauki Group) Asian and Indo-Burman plate rocks Greater Himalayan Crystalline Great Counter thrust complex Indian Craton Main Central thrust - South Tibet detachment Ophiolite / Ophiolitic Lesser Himalayan Sequence intersection line (white dash = buried, black melange dash = eroded) Figure 1. Simplifi ed geological map of the Himalaya, based on Webb et al. (2011b, and references therein). by enhanced erosion (in response to a climatic nating top-to-the-north and top-to-the-south nel tunneling” because of the proposed early change) across a narrow zone where precipita- shear along the South Tibet detachment (e.g., Miocene timing, and because the leading edge tion was focused along the topographic front of Hodges et al., 1996; Mukherjee and Koyi, 2010) of the modeled GHC was not exhumed by ex- the orogen (e.g., Beaumont et al., 2001; Hodges could be accommodated by slip transfer along a trusion. Rather, a localized, hinterland portion et al., 2001; Clift et al., 2008). second thrust wedge geometry across the GHC of the GHC and the early Miocene “lower” In both wedge extrusion and channel fl ow– hinter land (Webb et al., 2007). South Tibet detachment was extruded between focused denudation models, the Main Central Some workers have noted similarity be- the low-angle normal fault, termed the “upper” thrust and South Tibet detachment were active, tween tectonic wedging and channel tunneling South Tibet detachment, and an out-of-sequence surface-breaching faults during early-middle processes , as both feature southward motion thrust (the Kakhtang thrust). Restricted low- Miocene GHC emplacement. However, the of the GHC between two subhorizontal shear angle normal fault motion may be consistent South Tibet detachment map pattern in the west- zones that merge to the south (Kellett and Godin , with critical taper theory, as discussed above. ern and Bhutan Himalaya (Yin, 2006) and fi eld, 2009; Larson et al., 2010a). Modes of inter- and Alternatively, such faulting could result from structural, and U-Pb geochronologic studies in intra-unit shearing may indeed correspond. sub hori zontal shear tractions applied to the base the western and central Himalaya (Webb et al., Nonetheless, the kinematic models of channel of the Himalayan brittle upper crust by fl ow 2007, 2011a, 2011b) indicate that the South fl ow–focused denudation and tectonic wedging of middle crust (driven southward in response Tibet detachment intersects with the Main Cen- can be distinguished by two criteria: timing and to the lateral pressure gradient that varies with tral thrust at the leading edge of the GHC. This extrusion. In the fi rst model, proposed chan- topog raphy; Yin, 1989). frontal tip of the GHC is locally preserved; nel tunneling occurs in the Eocene–Oligocene, south of this tip, the THS is thrust directly atop preceding the Miocene surface emplacement Origins of Himalayan Material the LHS along the Main Central thrust. These of the GHC via channel fl ow coupled to extru- observations led to a third kinematic model— sion (e.g., Beaumont et al., 2001; Hodges et al., The fi rst model to include non-Indian mate- that the GHC was emplaced in the early-middle 2001; Godin et al., 2006). In contrast, proposed rial in the Himalayan orogen was the early chan- Miocene via tectonic wedging (Fig. 2C; Yin, tectonic wedging occurred in the Miocene nel fl ow concept of Nelson et al. (1996). These 2006; Webb et al., 2007). Model kinematics and accomplished emplacement of the GHC workers speculated that the GHC might repre- are analogous to thrust tectonics of the frontal at depth, without extrusion (Yin, 2006; Webb sent Tibetan middle crust that was thickened, Canadian Cordillera (Price, 1986): The South et al., 2011b).
Load more

Recommended publications
  • Arunachal Pradesh Yatra by Sanjeev Nayyar July 2014 I Spent Nearly
    Arunachal Pradesh Yatra By Sanjeev Nayyar July 2014 I spent nearly three weeks in Arunachal Pradesh, drove over 3,000 kms starting from Deomali in the east to Tawang in the west the last stop being Gauhati. It was one of the most intense drives and yatras of my life. We covered touristy places, schools, war memorials and border visit. This piece gives you the route that I took, places to see along the way plus links of pictures uploaded on esamskriti. Photo captions have travel tips etc. Travel Route I took a Mumbai-Kolkatta-Dibrugarh flight. If you book tickets in advance then get a cheap fare. INDIGO was bang on time – reliable as always. From Dibrugarh took a Tata Sumo. It is about a 3-4 hour drive to Ramakrishna Mission School, Narrottamnagar in Deomali. From RKM it is about an 8 hour drive to Teju. Route was Deomali- Godumsa-Namsai-Chowkham-Wakro-Parasuram Kund-Tezu. We stopped by at Chowkham, Wakro and Parasramkund. Tezu to Roing - there was a bridge being built over river in September 2013 when we went. If completed Tezu to Roing is about 2-3 hours. We had to take a longer route, took app 4 hours. From Roing Mayurdia is a 2 hour drive, can do a day trip. From Roing takes about 2 hours to reach the banks of the Brahmaputra – crossing the river takes one hour but might need to wait longer depending on boat availability. After crossing the river it is a 1.5 to 2 hour drive to Dibrugarh.
    [Show full text]
  • MARS DURING the PRE-NOACHIAN. J. C. Andrews-Hanna1 and W. B. Bottke2, 1Lunar and Planetary La- Boratory, University of Arizona
    Fourth Conference on Early Mars 2017 (LPI Contrib. No. 2014) 3078.pdf MARS DURING THE PRE-NOACHIAN. J. C. Andrews-Hanna1 and W. B. Bottke2, 1Lunar and Planetary La- boratory, University of Arizona, Tucson, AZ 85721, [email protected], 2Southwest Research Institute and NASA’s SSERVI-ISET team, 1050 Walnut St., Suite 300, Boulder, CO 80302. Introduction: The surface geology of Mars appar- ing the pre-Noachian was ~10% of that during the ently dates back to the beginning of the Early Noachi- LHB. Consideration of the sawtooth-shaped exponen- an, at ~4.1 Ga, leaving ~400 Myr of Mars’ earliest tially declining impact fluxes both in the aftermath of evolution effectively unconstrained [1]. However, an planet formation and during the Late Heavy Bom- enduring record of the earlier pre-Noachian conditions bardment [5] suggests that the impact flux during persists in geophysical and mineralogical data. We use much of the pre-Noachian was even lower than indi- geophysical evidence, primarily in the form of the cated above. This bombardment history is consistent preservation of the crustal dichotomy boundary, to- with a late heavy bombardment (LHB) of the inner gether with mineralogical evidence in order to infer the Solar System [6] during which HUIA formed, which prevailing surface conditions during the pre-Noachian. followed the planet formation era impacts during The emerging picture is a pre-Noachian Mars that was which the dichotomy formed. less dynamic than Noachian Mars in terms of impacts, Pre-Noachian Tectonism and Volcanism: The geodynamics, and hydrology. crust within each of the southern highlands and north- Pre-Noachian Impacts: We define the pre- ern lowlands is remarkably uniform in thickness, aside Noachian as the time period bounded by two impacts – from regions in which it has been thickened by volcan- the dichotomy-forming impact and the Hellas-forming ism (e.g., Tharsis, Elysium) or thinned by impacts impact.
    [Show full text]
  • Critical Analysis of Article "21 Reasons to Believe the Earth Is Young" by Jeff Miller
    1 Critical analysis of article "21 Reasons to Believe the Earth is Young" by Jeff Miller Lorence G. Collins [email protected] Ken Woglemuth [email protected] January 7, 2019 Introduction The article by Dr. Jeff Miller can be accessed at the following link: http://apologeticspress.org/APContent.aspx?category=9&article=5641 and is an article published by Apologetic Press, v. 39, n.1, 2018. The problems start with the Article In Brief in the boxed paragraph, and with the very first sentence. The Bible does not give an age of the Earth of 6,000 to 10,000 years, or even imply − this is added to Scripture by Dr. Miller and other young-Earth creationists. R. C. Sproul was one of evangelicalism's outstanding theologians, and he stated point blank at the Legionier Conference panel discussion that he does not know how old the Earth is, and the Bible does not inform us. When there has been some apparent conflict, either the theologians or the scientists are wrong, because God is the Author of the Bible and His handiwork is in general revelation. In the days of Copernicus and Galileo, the theologians were wrong. Today we do not know of anyone who believes that the Earth is the center of the universe. 2 The last sentence of this "Article In Brief" is boldly false. There is almost no credible evidence from paleontology, geology, astrophysics, or geophysics that refutes deep time. Dr. Miller states: "The age of the Earth, according to naturalists and old- Earth advocates, is 4.5 billion years.
    [Show full text]
  • “Anthropocene” Epoch: Scientific Decision Or Political Statement?
    The “Anthropocene” epoch: Scientific decision or political statement? Stanley C. Finney*, Dept. of Geological Sciences, California Official recognition of the concept would invite State University at Long Beach, Long Beach, California 90277, cross-disciplinary science. And it would encourage a mindset USA; and Lucy E. Edwards**, U.S. Geological Survey, Reston, that will be important not only to fully understand the Virginia 20192, USA transformation now occurring but to take action to control it. … Humans may yet ensure that these early years of the ABSTRACT Anthropocene are a geological glitch and not just a prelude The proposal for the “Anthropocene” epoch as a formal unit of to a far more severe disruption. But the first step is to recognize, the geologic time scale has received extensive attention in scien- as the term Anthropocene invites us to do, that we are tific and public media. However, most articles on the in the driver’s seat. (Nature, 2011, p. 254) Anthropocene misrepresent the nature of the units of the International Chronostratigraphic Chart, which is produced by That editorial, as with most articles on the Anthropocene, did the International Commission on Stratigraphy (ICS) and serves as not consider the mission of the International Commission on the basis for the geologic time scale. The stratigraphic record of Stratigraphy (ICS), nor did it present an understanding of the the Anthropocene is minimal, especially with its recently nature of the units of the International Chronostratigraphic Chart proposed beginning in 1945; it is that of a human lifespan, and on which the units of the geologic time scale are based.
    [Show full text]
  • Golden Spikes, Transitions, Boundary Objects, and Anthropogenic Seascapes
    sustainability Article A Meaningful Anthropocene?: Golden Spikes, Transitions, Boundary Objects, and Anthropogenic Seascapes Todd J. Braje * and Matthew Lauer Department of Anthropology, San Diego State University, San Diego, CA 92182, USA; [email protected] * Correspondence: [email protected] Received: 27 June 2020; Accepted: 7 August 2020; Published: 11 August 2020 Abstract: As the number of academic manuscripts explicitly referencing the Anthropocene increases, a theme that seems to tie them all together is the general lack of continuity on how we should define the Anthropocene. In an attempt to formalize the concept, the Anthropocene Working Group (AWG) is working to identify, in the stratigraphic record, a Global Stratigraphic Section and Point (GSSP) or golden spike for a mid-twentieth century Anthropocene starting point. Rather than clarifying our understanding of the Anthropocene, we argue that the AWG’s effort to provide an authoritative definition undermines the original intent of the concept, as a call-to-arms for future sustainable management of local, regional, and global environments, and weakens the concept’s capacity to fundamentally reconfigure the established boundaries between the social and natural sciences. To sustain the creative and productive power of the Anthropocene concept, we argue that it is best understood as a “boundary object,” where it can be adaptable enough to incorporate multiple viewpoints, but robust enough to be meaningful within different disciplines. Here, we provide two examples from our work on the deep history of anthropogenic seascapes, which demonstrate the power of the Anthropocene to stimulate new thinking about the entanglement of humans and non-humans, and for building interdisciplinary solutions to modern environmental issues.
    [Show full text]
  • Geologic Time and Geologic Maps
    NAME GEOLOGIC TIME AND GEOLOGIC MAPS I. Introduction There are two types of geologic time, relative and absolute. In the case of relative time geologic events are arranged in their order of occurrence. No attempt is made to determine the actual time at which they occurred. For example, in a sequence of flat lying rocks, shale is on top of sandstone. The shale, therefore, must by younger (deposited after the sandstone), but how much younger is not known. In the case of absolute time the actual age of the geologic event is determined. This is usually done using a radiometric-dating technique. II. Relative geologic age In this section several techniques are considered for determining the relative age of geologic events. For example, four sedimentary rocks are piled-up as shown on Figure 1. A must have been deposited first and is the oldest. D must have been deposited last and is the youngest. This is an example of a general geologic law known as the Law of Superposition. This law states that in any pile of sedimentary strata that has not been disturbed by folding or overturning since accumulation, the youngest stratum is at the top and the oldest is at the base. While this may seem to be a simple observation, this principle of superposition (or stratigraphic succession) is the basis of the geologic column which lists rock units in their relative order of formation. As a second example, Figure 2 shows a sandstone that has been cut by two dikes (igneous intrusions that are tabular in shape).The sandstone, A, is the oldest rock since it is intruded by both dikes.
    [Show full text]
  • Geological Society of America Bulletin
    Downloaded from gsabulletin.gsapubs.org on July 5, 2010 Geological Society of America Bulletin Geologic correlation of the Himalayan orogen and Indian craton: Part 2. Structural geology, geochronology, and tectonic evolution of the Eastern Himalaya An Yin, C.S. Dubey, T.K. Kelty, A.A.G. Webb, T.M. Harrison, C.Y. Chou and Julien Célérier Geological Society of America Bulletin 2010;122;360-395 doi: 10.1130/B26461.1 Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geological Society of America Bulletin Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society.
    [Show full text]
  • 4 the Drill Core 13
    P-06-03 Oskarshamn site investigation Fracture mineralogy Results from drill core KSH03A+B Henrik Drake Department of Geology, Earth Sciences Centre Göteborg University Eva-Lena Tullborg, Terralogica AB January 2006 Svensk Kärnbränslehantering AB Swedish Nuclear Fuel and Waste Management Co Box 5864 SE-102 40 Stockholm Sweden Tel 08-459 84 00 +46 8 459 84 00 Fax 08-661 57 19 +46 8 661 57 19 ISSN 1651-4416 SKB P-06-03 Oskarshamn site investigation Fracture mineralogy Results from drill core KSH03A+B Henrik Drake Department of Geology, Earth Sciences Centre Göteborg University Eva-Lena Tullborg, Terralogica AB January 2006 Keywords: Fracture minerals, Simpevarp, formation temperatures, ductile/brittle deformation, relative dating, wall rock alteration, red-ox, low-temperature minerals, calcite, stable isotopes, sandstone, adularia, hematite, clay minerals, XRD, SEM- EDS. This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the authors and do not necessarily coincide with those of the client. A pdf version of this document can be downloaded from www.skb.se Abstract The Swedish Nuclear Fuel and Waste Management Company (SKB) is currently carry- ing out site investigations in the Simpevarp/Laxemar area in the Oskarshamn region, in order to find a suitable location for long-time disposal of spent nuclear fuel. The drill core KSH03A+B from Simpevarp peninsula has been samples for detailed studies of fracture mineralogy. The sampling of fracture fillings was focused to a major deformation zone, striking NNE-SSW, although samples were also collected from above and below this zone.
    [Show full text]
  • Terminology of Geological Time: Establishment of a Community Standard
    Terminology of geological time: Establishment of a community standard Marie-Pierre Aubry1, John A. Van Couvering2, Nicholas Christie-Blick3, Ed Landing4, Brian R. Pratt5, Donald E. Owen6 and Ismael Ferrusquía-Villafranca7 1Department of Earth and Planetary Sciences, Rutgers University, Piscataway NJ 08854, USA; email: [email protected] 2Micropaleontology Press, New York, NY 10001, USA email: [email protected] 3Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades NY 10964, USA email: [email protected] 4New York State Museum, Madison Avenue, Albany NY 12230, USA email: [email protected] 5Department of Geological Sciences, University of Saskatchewan, Saskatoon SK7N 5E2, Canada; email: [email protected] 6Department of Earth and Space Sciences, Lamar University, Beaumont TX 77710 USA email: [email protected] 7Universidad Nacional Autónomo de México, Instituto de Geologia, México DF email: [email protected] ABSTRACT: It has been recommended that geological time be described in a single set of terms and according to metric or SI (“Système International d’Unités”) standards, to ensure “worldwide unification of measurement”. While any effort to improve communication in sci- entific research and writing is to be encouraged, we are also concerned that fundamental differences between date and duration, in the way that our profession expresses geological time, would be lost in such an oversimplified terminology. In addition, no precise value for ‘year’ in the SI base unit of second has been accepted by the international bodies. Under any circumstances, however, it remains the fact that geologi- cal dates – as points in time – are not relevant to the SI.
    [Show full text]
  • PHANEROZOIC and PRECAMBRIAN CHRONOSTRATIGRAPHY 2016
    PHANEROZOIC and PRECAMBRIAN CHRONOSTRATIGRAPHY 2016 Series/ Age Series/ Age Erathem/ System/ Age Epoch Stage/Age Ma Epoch Stage/Age Ma Era Period Ma GSSP/ GSSA GSSP GSSP Eonothem Eon Eonothem Erathem Period Eonothem Period Eon Era System System Eon Erathem Era 237.0 541 Anthropocene * Ladinian Ediacaran Middle 241.5 Neo- 635 Upper Anisian Cryogenian 4.2 ka 246.8 proterozoic 720 Holocene Middle Olenekian Tonian 8.2 ka Triassic Lower 249.8 1000 Lower Mesozoic Induan Stenian 11.8 ka 251.9 Meso- 1200 Upper Changhsingian Ectasian 126 ka Lopingian 254.2 proterozoic 1400 “Ionian” Wuchiapingian Calymmian Quaternary Pleisto- 773 ka 259.8 1600 cene Calabrian Capitanian Statherian 1.80 Guada- 265.1 Proterozoic 1800 Gelasian Wordian Paleo- Orosirian 2.58 lupian 268.8 2050 Piacenzian Roadian proterozoic Rhyacian Pliocene 3.60 272.3 2300 Zanclean Kungurian Siderian 5.33 Permian 282.0 2500 Messinian Artinskian Neo- 7.25 Cisuralian 290.1 Tortonian Sakmarian archean 11.63 295.0 2800 Serravallian Asselian Meso- Miocene 13.82 298.9 r e c a m b i n P Neogene Langhian Gzhelian archean 15.97 Upper 303.4 3200 Burdigalian Kasimovian Paleo- C e n o z i c 20.44 306.7 Archean archean Aquitanian Penn- Middle Moscovian 23.03 sylvanian 314.6 3600 Chattian Lower Bashkirian Oligocene 28.1 323.2 Eoarchean Rupelian Upper Serpukhovian 33.9 330.9 4000 Priabonian Middle Visean 38.0 Carboniferous 346.7 Hadean (informal) Missis- Bartonian sippian Lower Tournaisian Eocene 41.0 358.9 ~4560 Lutetian Famennian 47.8 Upper 372.2 Ypresian Frasnian Units of the international Paleogene 56.0 382.7 Thanetian Givetian chronostratigraphic scale with 59.2 Middle 387.7 Paleocene Selandian Eifelian estimated numerical ages.
    [Show full text]
  • Chapter 3 Sedimentary Rocks
    Chapter 3 Sedimentary Rocks Rivers that flow into the Gulf of Mexico through Alabama and other Gulf Coast states are typically brown, yellow-orange or red in color due to the presence of fine particulate material suspended within the water column. This particulate material is called sediment, and it was produced through the erosion and weathering of rocks exposed far inland from the coast (including the Appalachian Mountains). Sediment transported by rivers eventually finds its way into a standing body of water. Sometimes this is a lake or an inland sea, but for those of us that reside in southern Alabama, it is almost always the Gulf of Mexico. When rivers enter standing bodies of water (e.g., the Gulf), the sediment load that they are carrying is dropped and deposition occurs. Usually deposition forms more or less parallel layers called strata. Given time, and the processes of compaction and cementation, the sediment may be lithified into sedimentary rock. It is important to note that deposition of sediment is not restricted to river mouths. It also occurs on floodplains surrounding rivers, on tidal flats, adjacent to mountains in alluvial fans, and in the deepest portions of the oceans. Sedimentation occurs everywhere and this is one of the reasons why your humble author finds sedimentary geology so fascinating. Sedimentary rocks comprise approximately 30% of all of the rocks exposed at the Earth's surface. Those that are composed of broken rock fragments formed during erosion of bedrock are termed siliciclastic sedimentary rocks (or clastic for short). Sedimentary rocks can also be produced through chemical and biochemical deposition.
    [Show full text]
  • Arunachal Pradesh 3.2 Bihar 3.3 Jammu and Kashmir 3.4 Mizoram 3.5 Uttarakhand
    NATIONAL RURAL ROADS DEVELOPMENT AGENCY MINISTRY OF RURAL DEVELOPMENT GOVERNMENT OF INDIA Public Disclosure Authorized Pradhan Mantri Gram Sadak Yojana (PMGSY) - Social Assessment of World Bank Funded Second Rural Road Project Public Disclosure Authorized Public Disclosure Authorized Volume I Study Report - Draft Report February 2008 Public Disclosure Authorized 1 FAITH HEALTHCARE PRIVATE LIMITED f AITH 57. NEHKU PLACE (5THFLOOR), NEW DELHI - 110 01 9 CONSULTING ENGINEERING SERVICES (1) PVT. LTD. 57, NEHRU PLACE (5TH FLOOR), NEW DELHI - 110 01 9 Project: Social Assessment of Pradhan Mantri Gram Sadak Yojana (PMGSY) Sheet i of i Document: F2006040 February 2008 Draft Final Report \Contents Revision: R3 CONTENTS INTRODUCTION 2.0 WORKAPPROACHANDMETHODOLOGY 2.1 Study Approach 2.2 Study Methodology 2.3 State-wise Samples 2.4 Operational Limitations 3.0 SOCIO-ECONOMIC PROFILE OF THE STATES 3.1 Arunachal Pradesh 3.2 Bihar 3.3 Jammu and Kashmir 3.4 Mizoram 3.5 Uttarakhand 4.0 REVIEW OF RELEVANT POLICIES AND ACTS 4.1 International Policies 4.2 National Policies and Acts 4.3 State Specific Acts 5.0 WORKSHOP PROCEEDINGS AND SALIENT RECOMMENDATIONS 5.1 Workshop Objectives 5.2 Workshop Participants 5.3 Workshop Proceedings 5.4 Salient Recommendations and Future Actions for Stakeholders 6.0 STUDY Fl NDINGS 6.1 Assessment of Current Processes and Impacts 6.2 Findings from the PAP / PAF Survey 6.3 Findings from the FGDs 6.4 Constraints and Gaps ANNEXES Annex I - List of Abbreviations FAlT-l Healthcare Private Limited \\&lnre* wrO)\VOC WCmknO.da Project: Social Assessment of Radhan Mantri Gram Sadak Yojana (PMGSY) Sheet 1of 2 Document: F2006040 February 2008 Draft Final Report \ Vol.
    [Show full text]