bluuebunny/crossref_metadata_2025 huggingface dataset:
Volcaniclastic Rocks of the Carolina Slate Belt, Central North Carolina
Authors: Butler James Robert
Published: April 2015

The Carolina slate belt includes volcanic and sedimentary rocks of Late Precambrian and Cambrian age, metamorphosed to lower greenschist facies, that extend through the Piedmont from Georgia to Virginia. The segment in central North Carolina (Fig. 1) is probably the best-known part of the belt. Rocks in the Albemarle area are mildly deformed and metamorphosed; the dominant structures are open folds plunging southwest and the regional metamorphism is chlorite and biotite grade. The Albemarle region includes type localities for several stratigraphic units. The localities described here are on the Albemarle (Conley, 1962) and Denton (Stromquist, Choquette, and Sundelius, 1971) 15-minute quadrangles. The guidebook by Stromquist and Conley (1959) marked the beginning of modern studies in the central Carolina slate belt, as they demonstrated that stratigraphy and structure could be worked out on a regional basis. Conley and Bain (1965) applied formation names to the section in the Albemarle area (Fig. 2) and extended this stratigraphic nomenclature through most of the slate belt in North Carolina. In the Albemarle region, a thick, dominantly felsic volcanic unit (Uwharrie Formation) is overlain by a dominantly sedimentary sequence (Albemarle Group). The Morrow Mountain Rhyolite and Badin Greenstone of the Tater Top Group were interpreted to be the uppermost units and to lie with angular unconformity above folded older units (Conley and Bain, 1965). Stromquist and Sundelius (1969) reinterpreted part of the middle and upper stratigraphic sequence. They considered the Tater Tbp Group to be interlayered with other units of the Albemarle Group, rather than
Cretaceous-Paleocene Boundary, Lenoir County, North Carolina
Authors: Brown Philip M. , Miller James A.
Published: April 2015

In eastern Lenoir and western Craven Counties, located in the central part of the North Carolina Coastal Plain, a series of tilted and partially-exposed structural blocks define the limits, at the surface, of a zone of tectonic uplift and subsidence called the Graingers wrench zone (Brown and others, 1977). The segment of the wrench zone exposed at the surface is about 10 miles (16 km) long and 15 miles (24 km) wide. It trends NE-SW, plunges to the NE, is characterized by a sense of left-lateral displacement, and lies athwart the NW-SE trending Neuse River in the vicinity of Graingers, N.C.

The structural blocks characteristic of the wrench zone comprise a mosaic of juxtaposed grabens, half grabens, and horsts. In part, the blocks are composed of Navarroan, Midwayan and Claibornian sediments. The general boundaries of the blocks and their positions relative to each other, are established chiefly from the observed lateral discontinuity and variance in the relative vertical position of essentially flat-lying indurated mudstones (volcaniclastics) of Midway age, and from observed variance in elevation, relative to sea level, of the unconformity between Midwayan and Navarroan sediments.

The purpose of the field trip is to provide the participants with the opportunity to examine and collect from the Cretaceous-Tertiary boundary at five fresh exposures in the wrench zone, to collect from sections where the boundary is exposed, and to observe the manner in which rocks of different ages and and resistance (Midwayan porcelanites and Navarroan clayey sands) have reacted to the same
Deltaic Evolution During a Major Transgression
Authors: Eckard Timothy L. , Hayes Miles O. , Sexton Walter J.
Published: April 2015

The sedimentary deposits of the Santee River deltam, South Carolina, consist of two primary facies: (1) a 13-m-thick Late Pleistocene-Holocene alluvial sequence composed of coarse-grained, fluvial, point-bar deposits; overlain by (2) a 7-m-thick fine-grained deltaic complex. During the Wisconsin low stand of sea level, the river incised a deep valley, which in response to the Holocene sea-level rise, aggraded with fluvial deposits. During active channel migration within the confines of the valley walls, multistage, stacked, point-bar and channel sands were deposited. A decrease in river gradient brought about by the continued rise in sea level resulted in widespread overbank deposition and eventual stabilization of the fluvial channels by 7,000-5,000 BP. Sea-level stabilization at about this same time period initiated constructional phases of delta formation.

A stratigraphic model for delta evolution has been constructed through analysis of 63 vibracores, 45 power augers, 30 gouge augers, and 12 radiocarbon dates. The alluvial sediments comprising the valley fill unit are composed of pebbly, coarsegrained sand deposited as fluvial, multistage, stacked, point-bar and channel deposits capped by a widespread, fining- upward, sandy clay unit representing floodplain deposition. The overlying deltaic complex is a gently inclined, seaward–thickening sediment body consisting of a lower delta plain and delta front facies. The lower delta plain deposits are composed primarily of organic-rich muds deposited in freshwater swamp and open bay environments. In a seaward direction, these deposits interfinger with estuarine sands and muds deposited in back–barrier–related environments of the delta front. The present delta front is in a destructive phase as the shoreline is advancing landward beyond reworked, abandoned deltaic deposits in water depths of 5-10 m. The facies complex of the Santee River delta should provide some insight into the stratigraphic nature of medium-to small-sized deltas deposited in a mixed energy setting during a major transgression.
Upper Ordovician and Silurian Stratigraphy of the Virginia and West Virginia Valley and Ridge
Authors: Diecchio Richard J.
Published: April 2015

Two pronounced effects of the Taconic Orogeny were the creation of an eastern source area which influenced sedimentation through much of the Appalachian basin, and the early deformation of the eastern margin of the Appalachian basin. This field trip will investigate the stratigraphy of the Taconian (Upper Ordovician) and post-Taconian (Silurian) clastic strata in an attempt to illustrate the sedimentologic and structural effects of the Taconic Orogeny in the eastern portion of the Appalachian basin.

The Taconian clastic sequence is an orogenic progradational sequence. The distal (western) facies of the clastic sequence were deposited between the carbonate shelf and the source area, in a deep basin which was created by tectonic downwarping of the eastern edge of the carbonate bank. During deposition of the Taconian clastics, there occurred a pronounced, probably glacio-eustatic lowering of sea level, which lasted until the beginning of the Silurian.

The Silurian clastics are a series of post-orogenic quartz sandstones and mudrocks, the upper portion of which changes facies basinward to limestone. The sandstones comprise a number of tongues which are thickest near the basin margin, and thin to the west. The Silurian strata were deposited in relatively shallow water, implying that tectonic downwarping had ceased. The large-scale inter-tonguing of strata may have been caused by sea-level fluctuations.
Morphology and Stratigraphy of Mesotidal Shoreline Features
Authors: Hayes Miles O. , Sexton Walter J. , Imperato Douglas P.
Published: April 2015

This one-day field trip is designed to examine the morphology and stratigraphy of a mesotidal tidal inlet, Price Inlet, and barrier island, Capers Island, located in the central portion of the South Carolina coast. The tidal range in the study area averages around 2 m (mesotidal; Davies, 1964) and waves average 50-60 cm in height. Dominant longshore sediment transport is from north to south, with 150,000-200,000 m3 of sand moving past any given point on the Capers Island beach each year (Kana, 1976, 1979).

The field trip will be conducted at low tide, which will allow the participants to observe in detail intertidal features such as bedforms, swash bars, and inlet channels. Trenches dug through swash bars and beach berms will allow for detailed inspection of the internal sedimentary structures of these features. The main ebb channel of the inlet will be surveyed with a depth recorder and bottom samples will be collected along its length in order to demonstrate the effects of the tidal currents in shaping the inlet and its ebb-tidal delta. A 3 km walk along the front of the northern half of Capers Island, as well as a perpendicular transect across the island’s midsection, will expose the participants to all important aspects of the morphology of a typical regressive, mesotidal barrier island. A core taken in the middle of the island will be displayed in order to augment the description of the island’s Holocene stratigraphy.

An oblique aerial photograph of the area to be visited is
Cape Lookout Cuspate Foreland Depositional Systems
Authors: Moslow Thomas F. , Heron S. Duncan
Published: April 2015

The sedimentary record of 130 km of microtidal (0.9 m tidal range) high wave energy (1.5 m average wave height) barrier island shoreline of the Cape Lookout cuspate foreland has been evaluated through examination of 3136 m of subsurface samples from closely spaced drill holes. Holocene sedimentation and coastal evolution has been a function of five major depositional processes: (1) eustatic sea-level rise and barrier-shoreline transgression; (2) lateral tidal inlet migration and reworking of barrier island deposits; (3) shoreface sedimentation and local barrier progradation; (4) storm washover deposition with infilling of shallow lagoons; and (5) floodtidal delta sedimentation in back-barrier environments.

Twenty-five radiocarbon dates of subsurface peat and shell material from the Cape Lookout area are the basis for a late Holocene sea- level curve. From 9000 to 4000 B.P. eustatic sea level rose rapidly, resulting in landward migration of both barrier limbs of the cuspate foreland. A decline in the rate of sea-level rise since 4000 B.P. resulted in relative shoreline stabilization and deposition of contrasting coastal sedimentary sequences. The higher energy, northeast barrier li.h (Core and Portsmouth Banks) has migrated landward producing a transgressive sequence of coarse-grained, horizontally bedded washover sands overlying burrowed to laminated backbarrier and lagoonal silty sands. Locally, ephemeral tidal inlets have reworked the transgressive barrier sequence depositing fining-upward spit platform and channel-fill sequences of cross-bedded, pebble gravel to fine sand and shell. Shoreface sedimentation along a portion of the lower energy, northwest barrier limb (Bogue Banks) has resulted in shoreline progradation and deposition of a coarsening-up sequence of burrowed to cross-bedded and laminated, fine-grained shoreface and foreshore sands. In contrast, the adjacent barrier island (Shackleford Banks) consists almost totally of inlet-fill sediments deposited by lateral tidal inlet migration. Holocene sediments in the shallow lagoons behind the barriers are 5-8 m thick fining-up sequences of interbedded burrowed, rooted and laminated flood- tidal delta, salt marsh, and washover sands, silts and clays.

While barrier island sequences are 10 m in thickness, inlet-fill sequences may be as much as 25 m thick and comprise an average of 35% of the Holocene sedimentary deposits. Tidal inlet-fill, back- barrier (including flood-tidal delta) and shoreface deposits are the most highly preservable facies in the wave-dominated barrier-shoreline setting. In the Cape Lookout cuspate foreland, these three facies account for over 80% of the sedimentary deposits preserved beneath the barriers. Foreshore, spit platform and overwash facies account for the remaining 20%.
Field Trip Introduction
Authors: Harris Paul M. (Mitch) , Simo J. A. (Toni)
Published: April 2015

The Guadalupe and Hueco Mountains are exquisite natural laboratories for studying the stratigraphy, depositional facies, and diagenetic overprint of Permian platform and reef carbonates. Well-studied outcrops from these two classic localities serve as important analogs for other areas where the data is more limited. In addition, studies from the two areas have had immediate application to subsurface hydrocarbon exploration and exploitation efforts in the immediately adjacent Permian Basin.

Our field trip of three days will emphasize the stratigraphic framework, facies, and diagenesis of a Lower Permian (Wolfcampian) low-relief carbonate platform outcropping in the Hueco Mountains and an Upper Permian (Guadalupian) steep-rimmed platform of the Guadalupe Mountains. We invite questions and discussion at all field stops, as our group has diverse backgrounds and interests and any discussion will be beneficial to all.

The focus of the trip in the Hueco Mountains is on the evolution of the shelf-margin architecture and fauna! change. The exposures allow us to view the architectural elements of a prograding and retrograding shelf margin in ice-house conditions as well as the biotic response to environmental change. A relevant part of the exposure to visit is the facies variability both temporally and laterally.

Our emphasis in the Guadalupe Mountains is on the Capitan margin, as well as the related shelf and basin deposits. Large-scale outcrops like that of McKittrick Canyon offer an unparalleled view into the inside of a progradational platform, and we hope you will agree that the hike up the Permian Reef Geology Trail presents an
Hueco Mountains Introduction
Authors: Simo J. A. (Toni) , Wahlman Greg P. , Stoklosa Michelle. L. , Beall Jen L.
Published: April 2015

J. A. (Tom) Simo, Greg P. Wahlman, Michelle L. Stoklosa, Jen L. Beall

The Permian was a remarkable geological period, and it is reflected in the abundance of important sedimentary mineral resources. It represents the maximum stage of Pangeacontinental accretion, a gigantic continent from pole to pole surrounded by an all-encompassing ocean. The large Permsylvanian-Lower Permian Gondwana polar ice cap was at its maximum and later was partially replaced by large lakes. Chemically, Permian seas reached the most extreme values of carbon, sulfur, and strontium isotopic ratios, but returned abruptly to normal values close to the end of the Permian period (Scholle et al., 1995). Fauna and flora show an increasing provincialism that culminated at the end of the Permian with one of the largest extinction events in Earth’s history.

The Permian rocks reflect those extreme physical, chemical, and biologic changes. As such, the Permian sedimentary record is unique to explain changes in the biosphere, and the occurrence and distribution of economic deposits. For instance, from early to late Permian, source bed accumulation shifted from a period of major to minor occurrences respectively. The abundance of carbon in the sedimentary record is in part the reason of large early-middle Permian in age reserves of oil and gas (minimum global estimates are 28.4 MMM13 of oil and 6642 TCF of gas; Mazzullo, 1995). Similarly, the global cycle of phosphorous followed that of carbon (phosphorite deposits are early to middle Permian; Herring, 1995). The high carbon
Permian Platforms and Reefs in the Guadalupe and Hueco Mountains The
Capitan Margin of the Guadalupe Mountains
Authors: Harris Paul M. (Mitch)
Published: April 2015

The Late Permian (Guadalupian) mixed carbonate/siliciclastic sequences of the Delaware Basin, one of the long-lived subbasins of the Permian Basin, are well knovvn both for their classic outcrop exposures revealed by basin and range structuring in the Guadalupe Mountains and for their prolific hydrocarbon production (Figure 18). A large number of stratigraphic and sedimentologic studies have established the Capitan reef and associated facies as a model for the understanding of carbonate facies in a shelf margin setting and of reciprocal sedimentation relations between a shelf and basin. Early studies focused on biostratigraphy, lithostratigraphy, and early concepts of reciprocal sedimentation. Focus shifted in the 1970’s and 1980’s to analysis of depositional facies and processes and on the relatively new understanding of early diagenesis of reef margins. More recently, the outcrops have been analyzed from a cyclostratigraphy and sequence stratigraphy perspective. It will be interesting to see the impact of a refined stratigraphic fi-amework on the direction of future facies, paleo-ecological, and diagenetic studies.

Providing the initial interest in the area were the superb field studies and subsequent detailed reporting of the geology of the southern Guadalupe Mountains by King (1942, 1948). The book by Newell et al. (1953) on the Capitan did much to further enhance the outcrops as research models for sedimentary geologists. The critical treatment of the Capitan sedimentology by Dunham in the late 1950’s and 1960’s, culminating in his detailed 1972 guidebook, stimulated interest and added new understanding. Dunham’s work, plus the
Stratigraphic Evolution of Deep-Water Architecture
Authors: Covault J.A. , Crane W.H. , Bernhardt A. , Jobe Z.R. , Armitage D.A. , Fosdick J.C. , Shultz M.R. , Clark J. , Lowe D.R. , Graham S.A.
Published: April 2015

This large format (11 × 17 inch) all color outcrop atlas and field guide was produced for the SEPM Research Conference held in Chile in February, 2009. It contains a wealth of information on the world class deep water outcrops of the Cretaceous of the Magallanes Basin in the Ultima Esperanza District, Chilean Patagonia. This book covers the significant outcrops in the region the Punta Barrosa Formation, CerroToro Fm., and the Tres Pasos Fm.
Outcrops of the Magallanes Basin in the Ultima Esperanza District, Chilean Patagonia
Authors: Graham S.A. , Lowe D.R.
Published: April 2015

The Magallanes Basin SEPM Field Conference, February 2009, showcases outcrops of Cretaceous deep-water clastic strata exposed in the Ultima Esperanza District of southernmost Chile from Puerto Natales northward to Torres del Paine National Park. Why travel to the ‘end of the Earth’ to see these deep-water deposits? We believe that the deep-water succession in the Magallanes Basin of Chilean Patagonia is destined to join a select set of outcrop systems such as the Tanqua Karoo of South Africa (e.g., Wickens and Bouma, 2000; Johnson et al., 2001) and Brushy Canyon Formation of west Texas (e.g., Beaubouef et al., 1999; Gardner et al., 2003) as a world-class outcrop analog for buried, petroliferous deep-water systems. Magallanes Basin outcrops are notable for several key features: (1) Involvement in a latest Cretaceous – early Tertiary fold-thrust belt, providing nearly continuous down-depositional-dip 2-D outcrops for ~100 km, with local 3-D exposures provided by folding and topography; (2) Deep excavation and many bare-rock surfaces created by Late Cenozoic glaciation; (3) Contrasting styles of deep-water systems stratigraphically stacked during basin evolution, from unconfined and/or weakly-confined turbidite systems through highly-confined channelized systems through progradational failure-dominated delta slope with numerous channels and sand-filled mini-basins. The variability of the Magallanes Basin fill over a relatively small area makes the exposures of the Ultima Esperanza District worthy of the attention of the international sedimentologic community.

But it has not always been so. Cretaceous outcrops in the Magallanes Basin of the Ultima Esperanza District
Controls on Deep-Water Stratigraphic Architecture
Authors: Romans B.W. , Fildani A. , Hubbard S.M.
Published: April 2015

The effect of inherited attenuated crust from the closure of the predecessor backarc basin led to a relatively narrow orogenic belt during the Magallanes foreland development and a short distance from arc to foredeep. The attenuated crust heritage also provided continuous basinal subsidence (contributed to by fold-thrust belt loading and ophiolitic block obduction),which permitted long-lived (>20 my) deep-marine deposition and accumulation of >4000 m of turbiditic sediment that filled the basin axially in a north to south direction (Figs. ii.1A and C). Three distinct formations that reflect three distinct phases of deep-water deposition with different stacking patterns are featured in this document: the Punta Barrosa Formation, the Cerro Toro Formation, and the Tres Pasos Formation.

These three formations were deposited with contrasting stratigraphic architectures that we relate to two general factors: (1) variability in amount and type of source material (i.e., changes in provenance and/or staging area) and (2) variations in the basin shape throught time. Changes in the source and staging areas are represented by clear sedimentological differences, including the sandstone-and mudstone-dominated Punta Barrosa Formation with banded slurry beds, the conglomeratic channel-fill deposits of the Cerro Toro Formation, and the sandstone packages and mudstone-rich mass transport deposits of the Tres Pasos Formation slope system (Figs. ii.1B and C; see following page).

Basin morphology controls the general lay-out of depositional systems (e.g., channel dimensions, degree of confinement, dispersal patterns, etc.), which influences the distribution of sediment and resultant stacking patterns. We suggest
Deep-Water Sedimentary Facies of the Magallanes Basin
Authors: Fildani A. , Romans B.W. , Hubbard S.M.
Published: April 2015

The Tres Pasos Formation is a continental margin-scale progradational mudstone- to siltstone-rich slope succession. The lower part of this formation is characterized by an architecturally variable suite of sandstone-rich channel and sheet elements punctuated by mudstone-rich mass transport deposits. Sandstone-rich sedimentary bodies comprise massive sandstone (mostly high-density turbidity current deposits; S1 and S3 sensuLowe, 1982), intrabasinal mudstone-clast conglomerates, and various finer-grained turbidite facies (i.e., Bouma divisions; Bouma, 1962). The sandstone bodies exhibit a highly-variable internal architecture, including complex scour-and-fill features and lateral facies changes. Large-scale mudstone-dominated mass transport deposits (MTDs) typically contain mud-matrix supported debris flow deposits mixed with slide/slump blocks of variable sizes and are common between sandstone packages. The upper part of the Tres Pasos Formation is dominated by turbiditic mudstone and siltstone, hemipelagic mudstone, and sparse scours filled with coarse-grained pebbly material interpreted as by-pass conduits.
Outcrop 2. Punta Barrosa Formation Sheet Complex, Rio Serrano Section (New Roadcut)
Authors: Fildani A.
Published: April 2015

Outcrop accessibility: easy Outcrop Coordinates: 51.2177°S, 72.9606°W Refer to outcrop 2 on location map

A recently excavated roadcut at the Rio Serrano bridge (Fig. 2.1A), located just south of the Rio Serrano, is an easily accessible outcrop of the upper Punta Barrosa Formation. Stratigraphically positioned at the same level as the Marina’s Cliff outcrops (from which it is visible), this outcrop offers good lateral continuity of tabular architecture with few clear examples of scouring and amalgamation. Individual sandstone packets (elements) are almost entirely composed of slurry-beds with some intebedded packets of conventional fine-grained turbidites and mudstone (S4 and S6).

The slurry-beds in the roadcut exposure display a beautiful array of internal banding (micro-, meso-, and macro-banding, sensuLowe and Guy, 2000), consisting of bands of mud-rich (dark) and cleaner (light) sandstone within individual beds. Band thickness varies throughout beds, both laterally and vertically (B). Few beds evolve from meso-banding at the base into micro-banding at top (C). Water escape features are present throughout the beds, commonly as vertically oriented sheets in pale bands (D), sheared sheets in dark bands (D), and throughout massive beds (E; photo slightly higher in measured section). We interpret the slurry-beds to be the result of relatively rapid load fallout from turbidity currents, causing mud entrapment within sand falling out of suspension. The banding is interpreted in a similar way to the process described by Sylvester & Lowe (2004), whereby during rapid sedimentation, the high proportion of mud
Introduction to the Cerro Toro Formation in the Silla Syncline
Authors: Bernhardt A. , Crane W.H.
Published: April 2015

Outcrop accessibility: easy Outcrop Coordinates: 51.1199°S, 72.9701°W Refer to outcrops 4 and 5 on location map

The Silla Syncline is located within the Torres del Paine National Park east of Lago Pehoe and south of Lago Nordenskjöld. The Cerro Toro Formation in the area comprises more than 1100 m of deep-water strata within which Crane (2004) recognized and mapped three major coarse-grained channel complexes. These correspond to the informally named Pehoe, Paine and Nordenskjöld members, from oldest to youngest (Figs. iii.1, iii.2).

The Pehoe channel complex, consists of two conglomerate units, Pehoe A and B, separated by a 100-m-thick sequence of thick-bedded sandstones and thin interbedded mudstone units (see outcrop #4). The Paine member is subdivided into the Paine A, Paine B, Laguna Negra debris flow deposit, and the Paine C (see outcrop #5). Paine C is the largest channel in the section with a width of 2.5 to 3 km and a minimum thickness of 200 m (Figs. iii.1, iii.3 and iii.4). The Nordenskjöld member is exposed as a near continuous, roughly circular outcrop in the axis of the syncline north of the park highway (Fig. iii.3). This member is divided into two major subdivisions, Nordenskjöld A and Nordenskjöld B, separated by a thick debris flow deposit (Figs. iii.1 and iii.4).

The various channel complexes throughout the Silla Syncline section shifted locations as they were emplaced. The
Review of Interpretations for the Paine Channel Complex at Silla Syncline
Authors: Crane W.H. , Hubbard S.M. , Fildani A. , Romans B.W.
Published: April 2015

Multiple models have been proposed to account for the origin of channel and out-of-channel deposits in the Cerro Toro Formation at the Silla Syncline. The complex stratigraphic relationship between coarse-grained channel, and fine-grained out-of-channel deposits has been a topic of considerable debate in the scientific literature. Winn and Dott (1979), Beaubouef et al. (1996), and Beaubouef (2004) propose aggradational channel-levee models for the channel complexes present in the Parque Nacional Torres del Paine (Fig. iv.1A, B). Conversely, Coleman (2000), Crane (2004), and Crane and Lowe (2008) have proposed variations on an evolutionary model that invokes erosional confinement of channel sediments in background Cerro Toro Formation mudstone (Fig. iv.1C, D). The high-energy axial portion of the best-exposed and most well studied channel complex (Paine C of Crane et al., 2008) is a minimum of 4 km wide and the Silla Syncline provides only an oblique cross-section through the complex (Fig. iv.1D). If the system is levee confined, the coeval levees must have added substantially to the cross-sectional width of the channel complex; post-depositional structures both east and west of the syncline limit the preserved width to only slightly more than the channel axis in most areas. As a result it is difficult to discern whether the erosional margins preserved in outcrop represent the edges of an incisional channel complex, or the eroded inner margins of extensive levees.
Outcrop 4. Pehoe Member
Authors: Bernhardt A. , Jobe Z.R. , Lowe D.R.
Published: April 2015

Outcrop accessibility: easy Outcrop Coordinates: 51.1199°S; 72.9701°W Refer to outcrop 4 on location map

The Pehoe channel complex consists of two conglomerate units, Pehoe A and B (nomenclature of Crane, 2004), separated by a 100 m-thick sequence of thick-bedded sandstones and thinly interbedded mudstone units (Fig.4.1A and B). The Pehoe A member consists of the Pehoe A conglomerate and the Pehoe A thick-bedded sandstone and mudstone. The Pehoe B member is subdivided into the Pehoe B conglomerate and the associated Pehoe B mass transport deposits.
Outcrop 5. NW Margin of the Paine ‘C’ Channel Complex, Silla Syncline
Authors: Crane W.H. , Lowe D.R.
Published: April 2015

Outcrop accessibility: easy Outcrop Coordinates: 51.1199°S; 72.9701°W Refer to outcrop 5 on location map

The northwestern portion of the Paine C channel complex (Fig. 5.1A) is easily accessible from the Torres del Paine park highway. Exposures of the Paine C continue throughout the axis of the Silla Syncline from the park highway south to Laguna Negra (Fig. 5.1B). Stratigraphically, the Paine C lies directly above a regionally correlated mass transport complex informally named the Laguna Negra Debris Flow (Fig. 5.1C). The channels within the complex show overall paleoflow toward the southeast and south (Figs. iii.5 and 5.1C). The greatest preserved thickness of channel deposits trends southeast from section 11 to section 21 at the southeastern edge of the syncline (Fig. 5.1B). Given the orientation of the channel complex with respect to paleoflow, the limbs of the Silla Syncline expose a somewhat oblique cross-sectional view of the Paine C channel complex (Fig. 5.1C).

Measured sections along the west limb of the syncline demonstrate that the Paine C thickens progressively to the south by the addition of sediment at the top of the section. A minimum of six stacked channel margins are present between the park highway and Lago Sarmiento Chico (Fig. 5.1C). Channel margins are identified by erosional surfaces which may or may not be mudstone draped and against which sandstones, conglomerates and interbedded sandstone and mudstone units onlap. The approximate locations of
Outcrop 6. Cerro Toro Channel Margins, Sierra del Toro
Authors: Jobe Z.R. , Bernhardt A. , Fosdick J.C. , Lowe D.R.
Published: April 2015

Outcrop accessibility: N face - moderate; S face - extremely difficult Outcrop Coordinates: N face = 51.0781°S, 72.6999°W; S face = 51.1284°S, 72.6813°W Refer to outcrop 6 on location map

Deposits of the Cerro Toro Formation on Sierra del Toro represent the most proximal axial channel belt deposits preserved in the Magallanes Basin outcrop belt, based on regional paleogeographic interpretations (Scott, 1966; Hubbard, 2006; Hubbard et al., 2008b). Scott (1966) provided the first description of conglomeratic deposits on Sierra del Toro; Winn and Dott (1979) interpreted this location as part of an elongate submarine fan that filled the basin axis from north to south.

Cerro Toro Formation outcrops on Sierra del Toro include at least three conglomeratic units, each of which is interpreted to represent a submarine channel complex. These channel complexes were deposited within an axial channel belt (Fig. 6.1A and 6.1B). The units are hereby informally named, from oldest to youngest, the “Condor” (Barton et al., 2008), “Guanaco”, and “Wildcat” channel complexes.
Outcrop 7. Wildcat Channel Complex Axis-to-Margin Architecture, Sierra del Toro
Authors: Jobe Z.R. , Bernhardt A. , Hubbard S.M. , Lowe D.R.
Published: April 2015

Outcrop accessibility: difficult Outcrop Coordinates: 51.0852°S, 72.6541°W Refer to outcrop 7 on location map

The Wildcat channel complex is up to 5–6 km wide and 330 m thick, making it the largest exposed on Sierra del Toro. Hubbard and Shultz (2008) suggest that this channel complex is stratigraphically equivalent to the upper two-thirds of the conglomeratic portion of the Cerro Toro Formation at Cerro Castillo, located due south of Sierra del Toro adjacent to the south shore of Lago del Toro. A portion of the eastern Wildcat channel margin was characterized by Hubbard et al. (2008b) (outcrop featured in Fig. 7.2E, referred to as “Sarmiento Vista” by Hubbard et al., 2008b).

The eastern margin of the Wildcat channel complex is well exposed on the northeast face of the mountain, displaying 200 m of conglomeratic channel fill thinning until its final pinchout (Figs. 7.1B and 7.2). This exposure allows for a direct correlation of beds along a ~3 km transect oblique to depositional strike (1.5 km when projected parallel to strike; Fig. 7.3). The slope of the margin averages approximately 7.5° over this distance, although it is partitioned into a steep ‘wall’ at its base, near the channel complex axis, and a shallower ramp nearer the final pinchout (Fig. 7.3). As a result, the eastern margin is characterized by a “steerhorn” cross-sectional profile. Paleoflow measurements taken at the margin of the channel complex
Outcrop 8. Channel Margins in the Cerro Toro Formation, Cordillera Manuel Señoret
Authors: Hubbard S.M. , Romans B.W.
Published: April 2015

Outcrop accessibility: variable Outcrop Coordinates: 51.4716°S, 72.6508°W Refer to outcrop 8 on location map

Conglomeratic deposits of the Cerro Toro Formation attributed to deposition in a large-scale basin axial channel belt are well exposed in the Cordillera Manuel Señoret, north of Puerto Natales between Cueva del Milodon and Lago Toro. The conglomeratic succession is informally called the “Lago Sofia Member” because of the presence of Laguna Sofia in this area (Scott, 1966). The large injectite complex that is the focus of Chapter 9 is present in the Cordillera Manuel Señoret on the south shore of Lago Sofia (Fig. 8.1A).

The channel belt is characterized by low sinuousity, demonstrated with outcrop mapping and the collection of extensive paleocurrent data (Fig. 8.1A). Outcrop exposures of the channel belt margin are present on the north faces of Cerro Benitez and Cerro Mocho (Fig. 8.1B, C). Because of poor accessibility, the margin at Cerro Mocho cannot be easily visited.

A levee interpretation for fine-grained material adjacent to the channel belt is based on a series of key observations: (i) paleocurrent measurements indicative of flow divergence (50° to 100°) measured from out-of-channel units as compared to those taken from inside the channel belt container; (ii) progressive thinning of sandstone beds away from the channel belt margin; (iii) evidence that the eroded channel margin was poorly indurated, including a stepped profile and injection of channel fill into out-of-channel strata; (iv) deposits that record slumping on the
Outcrop 9. Clastic Injectites in the Cerro Toro Formation, Lago Sofia
Authors: Hubbard S.M. , Romans B.W. , Graham S.A.
Published: April 2015

Outcrop accessibility: easy Outcrop Coordinates: 51.5394°S; 72.6291°W Refer to outcrop 9 on location map

The injectites at Lago Sofia were first reported by Scott (1966) and Winn and Dott (1979). The first comprehensive evaluation of the features was done by Schmitt (1991), with a more recent summary published by Hubbard et al. (2007), who noted the geometrically analogous nature of the injectites to similar features in the North Sea.

The injectites at Lago Sofia are exposed in 3-D, characterized by a near vertical outcrop of channel deposits in the lowest part of the succession. The middle part of the succession where the injectites are most prevalent is exposed on an ancient terrace, allowing for plan-view mapping of the injectite complex. The upper part of the stratigraphic succession is exposed sub-vertically, permitting visualization of the cross-cutting relationships between injectites and host strata (Fig. 9.1).

A series of three channel bodies (C1–C3) are laterally offset and progressively younger eastward. Each channel body is associated with injected bodies at its margins. Both margins of C1 experienced sediment remobilization and injection. Channel C2 experienced injection solely on its western margin; the associated injectite, I3, bifurcates and is observed to cross-cut >125 m of overlying stratigraphy. Channel C3 is the smallest, as is its accompanying injectite (I4).
Outcrop 10. Tres Pasos Slope Sandstone Bodies, Cerro Divisadero
Authors: Romans B.W. , Hubbard S.M. , Graham S.A.
Published: April 2015

Outcrop accessibility: extremely difficult Outcrop Coordinates: 50.7048°S, 72.7361°W Refer to outcrop 10 on location map

The Tres Pasos Formation (1000–1500 m thick) records the transition from bathyal water depths of the upper part of the Cerro Toro Formation to the shallow-marine and deltaic facies of the overlying Dorotea Formation. The lower part of the Tres Pasos Formation exposed at Cerro Divisadero (600 m thick) is the northernmost (most landward) of the Tres Pasos outcrop locations in this guidebook. Four sandstone-rich packages that range in thickness from 20 to 80 m are recognized and mapped across a ~3 km long outcrop transect. The north-south trending outcrop is generally parallel to depositional dip (basinward to the south), although ridge-and-gully topography provides three-dimensionality at a smaller scale (10s to 100s of meters). The four sandstone-rich units are separated by intervals of shale and siltstone tens of meters thick. Unit 1 is partially covered and minor post-depositional structure (reverse faults and associated drag folds) disrupt detailed architectural characterization of Unit 4. Units 2 and 3 are, therefore, the focus of the panels in this guidebook. Refer to Romans et al. (2008) for detailed presentation and interpretation of the Tres Pasos Formation at Cerro Divisadero.
Outcrop 11. Tres Pasos Formation Slope Deposits Overview, Rio Zamora Canyon
Authors: Romans B.W. , Fildani A. , Hubbard S.M.
Published: April 2015

Outcrop accessibility: very difficult - Overview accessibility: easy Outcrop Coordinates: 50.8166°S, 72.6947°W Refer to outcrop 11 on location map

Outcrops of the Tres Pasos and Dorotea formations in northern Ultima Esperanza District highlighted in this field guide (outcrops 10, 12, and 15) are remote and extremely difficult to access. One way to appreciate the general characterstics of the strata is from a distance along a dirt road on the west side of the north-south flowing Rio Zamora, which has carved a canyon into the Tres Pasos Formation and upper Cerro Toro Formation. From within the boundaries of Parque Nacional Torres del Paine, take the road to “Laguna Azul” and continue heading north (Fig. 11.1A) (note: at the time of publication, this road went through private land with unlocked gates; please always respect private land and communicate your intentions to stay on road and view outcrops from afar). The outcrops are on the other side of Rio Zamora from this road; do not attempt to cross the river. From north to south, the outcrop belt straddles three mountains: Cerro Divisadero, Cerro Mirador, and Sierra Contreras. Abundant paleocurrent data from the Tres Pasos Formation in this area indicate that basinward was to the south-southeast (Shultz et al., 2005; Romans et al., 2008). The transect displayed in this river canyon is therefore generally parallel to depositional dip, providing an opportunity to see a dip-parallel slope cross-section. Some east-west tributary
Outcrop 12. Tres Pasos Formation Mass Transport Deposit Topography, Sierra Contreras
Authors: Armitage D.A. , Romans B.W. , Covault J.A. , Graham S.A.
Published: April 2015

Outcrop accessibility: difficult Outcrop Coordinates: 50.8859°S, 72.6545°W Refer to outcrop 12 on location map

At Sierra Contreras, deep-water slope depositional relationships between fine-grained mass transport deposits (MTDs) and overlying turbiditic sandstones can be assessed. The lateral continuity of sandstone-rich reservoir-scale bodies was dominantly controlled by original seafloor topography, related to the morphology of underlying MTDs. Overlying sandstone beds pinch-out and lap onto the relative topographic highs of the MTDs. Turbidite architecture evolves to more laterally continuous, sheet-like deposits as a result of depositional smoothing of MTD relief and diminished confinement (Shultz et al., 2005; Armitage et al., in press).

Small-scale MTD topography, characterized by several meters of vertical relief, was associated with local pockets of accommodation where sands were ponded. These small-scale surface irregularities are inferred to have been associated with the rugose tops of viscous MTDs. Meso-scale MTD topography (10 to several 10s of meters relief) was created by coherent rafted sandstone blocks resting on top of, or within the upper portion of MTD deposits; it is onlapped by overlying sandstone beds. This topography can laterally compartmentalize significant packages of sandstone. The largest scale of topography identified (several hundred meters horizontally and vertically) resulted from individual mass-wasting events (e.g., outsized block emplacement) creating topographic relief at the time of deposition. Topographic features at this scale can laterally divide large-scale sediment gravity flow pathways, leading to significant compartmentalization of sandstone bodies.

The size and abundance of rafted blocks in MTDs increases vertically in the outcrop suggesting
Outcrop 15. Transition from Deep-Water to Shelf Edge Deposits,Tres Pasos and Dorotea Formations, Cerro Escondido
Authors: Covault J.A. , Romans B.W. , Graham S.A.
Published: April 2015

Outcrop accessibility: extremely difficult Outcrop Coordinates: 50.7309°S, 72.6324°W Refer to outcrop 15 on location map

The stratigraphic section at Cerro Escondido contains the most complete exposure of the Dorotea Formation in the Ultima Esperanza District (Fig. 15.1). Cerro Escondido is located south of the Argentina-Chile border on an anticline between the Rio de las Chinas and the Rio Zamora (refer to outcrop location map). The contact between the Tres Pasos and Dorotea formations had not been formally mapped at Cerro Escondido, and we define it as the first contact between turbidites of the Tres Pasos Formation and overlying shallow-marine hummocky-cross stratified sandstone of the Dorotea Formation (Fig. 15.1). Greater than 300 m of stratigraphy are exposed across >800 m of the Cerro Escondido outcrop (Fig. 15.1). Two stratigraphic sections were recorded at cm-scale resolution (295 m thick in the east and 197 m thick in the west; Fig. 15.1C).
Decomposition of Avicennia marina (Forsk.) Vierh. Foliage under field and laboratory conditions in the backwaters of Karachi, Pakistan
Authors: Shafique Seema , Siddiqui Pirzada JA , Aziz RA , Shaukat SS , Farooqui Z
Published: April 2015

The fate of leaf litter decomposition of Avicennia marina (Forsk.) Vierh. was found higher under field aerobic condition (FAC) while the fate was lowest under laboratory anaerobic condition (LAAC). The time required for the loss of half of the initial day weight (t50) was 48, 55, 98 and 110 days for aerobic condition (AC), field micro-aerobic condition (MAC), laboratory aerobic condition (LAC) and LAAC, respectively. Total nitrogen content of the decomposing litter increased by contrast, total organic carbon decreased during decomposition. Consequently, carbon to nitrogen ratios declined with time during decomposition. Repeated measure design showed that weight loss, total nitrogen and total organic carbon vary significantly under all four conditions with respect to elapsed time (p < 0.001; WilksLambda = 0.02, 0.003, 0.02, respectively at p < 0.001). The study concludes that mangrove litter has an initial rapid phase of decomposition and the variable decay rates depend on the degree of exposure/submergence of litter in water, the pressure of detrivores, and the oxygen level in the given niche of mangrove forest. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22716 Bangladesh J. Bot. 44(1): 1-7, 2015 (March)
Effects of foliar application of nutrients on growth and yield of Bt cotton (Gossypium hirsutum L.)
Authors: Singh Kulvir , Rathore Pankaj , Gumber RK
Published: April 2015

Field experiments were conducted for three years during Kharif 2009-2011 to study the effect of foliar application of nutrients (N, Mg, Fe, Zn, Mn and B) on growth and yield parameters of Bt cotton. Pooled data indicated highest seed cotton yield (3421.4 kg/ha) with application of MgSO4 1.0%+ ZnSO4 0.5%. Better net returns ( 100760/ha) and improved B:C (4.06) ratio for MgSO4 1.0% + ZnSO4 0.5% clearly supported its application benefits to realize higher yield . DOI: http://dx.doi.org/10.3329/bjb.v44i1.22717 Bangladesh J. Bot. 44(1): 9-14, 2015 (March)
Amelioration of seed yield, oil content and oil quality through induced mutagenesis in sesame (Sesamum indicum L.)
Authors: Begum Tamina , Dasgupta Tapash
Published: April 2015

Thirty mutant lines selected from 3 widely adapted genotypes of sesame viz. Rama, SI 1666 and IC 21706 (ten from each of the three genotypes), developed by induced physical (?-rays) and chemical (EMS) mutagens, were evaluated against their respective control genotype for yield and its important attributes in M4 generation to reveal the ramification of mutagens for disclosing the magnitude of variation among mutants in advance generation and also to identify the promising positive mutants to refurbish new improved varieties of sesame. Mutants professing higher seed yield were evaluated for oil quantity and quality. All selected mutant lines evinced improved seed yield over their respective controls. Irrespective of the genotypes highest yield was recorded in the line induced by 0.5% EMS. Based on mean seed yield and its components, selected 10 superior mutants, also possessed high oil percentage with a better oil profile having relatively more polyunsaturated fatty acid content, specially linoleic acid, than the control, indicating potentiality of mutation breeding to restructure plants with high yield, improved oil percentage and quality. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22718 Bangladesh J. Bot. 44(1): 15-22, 2015 (March)
Phenotyping and genetic evaluation of sterile cytoplasmic male sterile analogues in sunflower (Helianthus annuus L.)
Authors: Tyagi Vikrant , Dhillon SK , Bajaj RK , Gupta Shilpa
Published: April 2015

Nine new cytoplasmic male sterile (CMS) analogues on the basis of different CMS sources were developed and evaluated for morphophysiological, yield and biochemical traits. Analysis of variance indicated significant differences between CMS analogues for all the traits. The genetic components analysis indicated that selection for grain yield accompanied with high harvest index, large head size and biological yield can be effectively used for genetic improvement in sunflower. D2analysis revealed sufficient diversity between CMS analogues which can be exploited for developing hybrids based on different cytoplasmic sources. Intra-cluster distance of 72.5 observed for the analogues present in cluster I (E002-91A, ARG-2A, DV-10A and PRUN-29A) revealed cytoplasmic dissimilarity between these sources. CMS ARG-3A was the most diverse CMS lines among all. As a result of this study the most prospective CMS analogues were designated for future use in hybrid breeding programme. The CMS analogues PRUN 29A and ARG 3 may be effectively used for developing high seed and oil yielding hybrids with desirable fatty acid composition. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22719 Bangladesh J. Bot. 44(1): 23-30, 2015 (March)
Pollen micromorphology of four taxa of Anemone coronaria L. from western Turkey
Authors: Candan Feyza , Çali Ilkay Öztürk
Published: April 2015

The present study examined a comparison of the pollen micromorphology of four taxa of Anemone coronaria L. (A. coronaria var. coccinea (Jord.)) Burn, A. coronaria var. rosea (Hanry) Batt, A. coronaria var. cyanea, A. coronaria var. alba Goaty & Pens) naturally distributed in western Turkey and its commercial cultivars of de Cean group. Measurements of pore width-length and exine-intine layer thicknesses were made using a micrometric ocular. In this study pore width-length and exine-intine layer thicknesses were found as decreased in all Anemone coronaria L. cultivars of de Cean group in respect to the varieties. The reasons for this variation could be the use of pesticides and tetraploid F1 hybrids of Anemone coronaria L. cultivars of de Caen group by the producers. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22720 Bangladesh J. Bot. 44(1): 31-36, 2015 (March)