Hills Plateau Research Articles

Snakehead (Teleostei: Channidae) diversity and the Eastern Himalaya biodiversity hotspot

The collision of the Indian and Eurasian landmasses in the Cenozoic was a decisive factor in shaping biodiversity patterns in Southern and Southeastern Asia. While most studies thus far have focused on the biotic interchange between India and Eurasia and evolutionary diversification on or around the Tibetan Plateau, little attention has been paid to the biodiversity buildup in the Eastern Himalaya biodiversity hotspot (EHH) which harbors over 540 freshwater fish species with a high degree of endemicity. An important component of the regional ichthyofauna are snakehead fishes of the family Channidae comprising throughout their African‐ Asian distribution 47 valid species, but a poorly known species‐level diversity. In order to evaluate channid intrarelationships and biogeography, a temporal and geographic framework of channid evolution in conjunction with a critical reevaluation of the channid fossil record is warranted. Based on molecular data, we provide a comprehensive species‐level phylogeny based on 223 channid individuals belonging to 37 species and one additional currently undescribed species. The first split within channids separates the African genus Parachanna from the Asian genus Channa which can be divided into eight distinct species groups (Argus, Asiatica, Gachua, Lucius, Marulius, Micropeltes, Punctata, and Striata groups). Large intraspecific divergences were observed within several species and potentially indicate additional species‐level diversity. Almost 40% of the channid species are narrow‐range endemics belonging to the Gachua group. These are found in the EHH making this area an outstanding hotspot for endemic channid diversity. The large majority of the EHH endemics are restricted to the southern foothills of the Eastern Himalaya and the Shillong‐Mikir Hills Plateau, areas west of the Indoburman Ranges. Our results reveal complex and difficult to interpret biogeographic patterns indicating that both vicariance and dispersal events have potentially been responsible in shaping current distribution patterns in Asian channids. We recognize †Parachanna fayumensis as the oldest reliable channid fossil and argue that the three oldest so‐called channid fossils (i.e., †Eochanna chlorakkiensis, †Anchichanna kuldanensis, and †Ophiocephalus lydekkeri) lack clear diagnostic features that would allow them to be unequivocally placed within Channidae.

Dynamics of Mikir hills plateau and its vicinity: Inferences on Kopili and Bomdila Faults in Northeastern India through seismotectonics, gravity and magnetic anomalies

he Mikir Hills plateau is encompassed by two prominent faults – Bomdila Fault to the east and the Kopili Fault to the west characterized by strike-slip kinematics. The Kopili Fault has a dip of 75 o towards NE. Simultaneously, the Bomdila Fault dips with 50-55 o towards the NNE. An integrated approach based on seismotectonics, gravity and magnetic data is utilized to understand the tectonic activity of the Kopili and Bomdila Faults. The bottom of seismogenic zones is inferred to be 45 + 2 km and 50 + 2 km for the Kopili Fault and the Bomdila Fault region respectively. So far gravity anomaly is concerned; it varies between -110 to +60 mgals along the Kopili –Bomdila Fault regions from the Belt of Schuppen to the MCT. The low gravity values over the Bomdila Fault area indicate presence of thick alluvial deposits while along Kopili Fault lesser sediment thickness is observed. Simultaneously, basement being at shallower depth, lower magnetic values indicate presence of thick alluvial deposits in and around Bomdila Fault. The curvatures and closures of the gravity contours along the fault lines indicate structures involving basement and indicate influence of Bomdila Fault up to the basement. Simultaneously, it is observed that Kopili and Bomdila faults are neotectonically active. All these are the prime input to the seismic hazard assessment of the region.

Modelling of the Kopili Fault based on slip rate, moment rate and seismic activity in Mikir Hills Plateau of Northeastern India

ABSTRACTThe recurrence period of maximum magnitude earthquake in a seismogenically active formation along the Kopili Fault has been estimated having adequate dependence on the slip rate, moment rate and its seismicity pattern. Here, the frequency–magnitude cum fault area–maximum magnitude relations play a key role with input parameters pertinent to the Kopili Fault zone. Subsequently, where the fault slip rate estimates are not available, the seismic activity is studied from the seismic moment release. The results of this study show that the return period has a strong relation with the fault length, slip rate, strain drop and rigidity. This study ascertains the activity rate in terms of the return period as ∼50 ± 5 years with the moment release of 2.12E+23 dyne-cm from the most active 80-km fault length considering Mw 5.5 as reference magnitude under the Kopili Fault zone that may produce a maximum magnitude of Mw ∼ 7.6. Finally, we conclude that these models can be used to study the rate of seismicity of the active faults in Northeast India which will provide us prime inputs for seismic hazard analysis of the region and is especially significant for estimating expected return period for poorly known faults or blind faults that lack surface expression.

Refinement of lunar TiO2 analysis with multispectral features of Chang’E-1 IIM data

We develop a method based on the samples from Apollo and Luna landing sites to determine lunar TiO2 content with Chang’E-1 interference imaging spectrometer (IIM) imagery. By analyzing the nonlinear relationship between the optical and compositional parameters of lunar soil samples, the method employs two Support Vector Machines (SVMs) to estimate the titanium abundance of the lunar surface. Developed with the soil compositions of the Apollo and Luna sample-return stations, the RMS (root mean square) error of our method is 0.24 wt% TiO2, and the correlation coefficient of the TiO2 values and our predicted ones is 99.72 %. Compared with the other 3 models, the method proposed in this paper exhibits a good performance for determining the chemical composition of the lunar surface. TiO2 maps of Sinus Iridum, part of the Marius Hills plateau, and part of Mare Smythii are produced using our method, which could be useful for future lunar missions.

Mapping the crustal thickness in Shillong–Mikir Hills Plateau and its adjoining region of northeastern India using Moho reflected waves

In this study we have tried to detect and collect later phases associated with Moho discontinuity and used them to study the lateral variations of the crustal thickness in Shillong–Mikir Hills Plateau and its adjoining region of northeastern India. We use the inversion algorithm by Nakajima et al. (Nakajima, J., Matsuzawa, T., Hasegawa, A. 2002. Moho depth variation in the central part of northeastern Japan estimated from reflected and converted waves. Physics of the Earth and Planetary Interiors, 130, 31–47), having epicentral distance ranging from 60km to 150km. Taking the advantage of high quality broadband data now available in northeast India, we have detected 1607 Moho reflected phases (PmP and SmS) from 300 numbers of shallow earthquake events (depth⩽25km) in Shillong–Mikir Hills Plateau and its adjoining region. Notably for PmP phase, this could be identified within 0.5–2.3s after the first P-arrival. In case of SmS phase, the arrival times are observed within 1.0–4.2s after the first S-arrival. We estimated the crustal thickness in the study area using travel time difference between the later phases (PmP and SmS) and the first P and S arrivals. The results shows that the Moho is thinner beneath the Shillong Plateau about 35–38km and is the deepest beneath the Brahmaputra valley to the north about 39–41km, deeper by 4–5km compared to the Shillong Plateau with simultaneous observation of thinnest crust (∼33km) in the western part of the Shillong Plateau in the Garo Hills region.

Estimation of crustal discontinuities from reflected seismic waves recorded at Shillong and Mikir Hills Plateau, Northeast India

In this study, an attempt is made to determine seismic velocity structure of the crust and upper mantle beneath the Shillong-Mikir Hills Plateau in northeast India region. The principle of the technique is to relate seismic travel times with crustal thickness above the Conrad and Moho discontinuities. Broadband digital waveforms of the local earthquakes make a precise detection of the seismic phases possible that are reflected at these discontinuities. The results show that the Conrad discontinuity is at 18–20 (±0.5) km beneath the Shillong-Mikir Hills Plateau and the Moho discontinuity is at 30 ± 1.0 km beneath the Shillong Plateau and at 35 ± 1.0 km beneath the Mikir Hills.

Tree and forest encroachment into fescue grasslands on the Cypress Hills plateau, southeast Alberta, Canada

Tree encroachment into rough fescue ( Festuca campestris) grassland has been identified as an ecological concern on the Cypress Hills plateau in southeastern Alberta, Canada. A combination of field sampling (109 transects), a dendrochronological assessment (1361 trees), and a time series analysis of remotely sensed images from five different time periods (1950–2002) were used to determine the extent and rate of tree encroachment and forest development. Tree cover increased by 768 ha (∼51%) between 1950 and 2007, representing 10% of the study area, from 1502 ha of pre-1950 forest. Post-1950 tree invasion also created an ingress zone of 750 ha (∼10% of study area) based on field transects. Forest cover increased at a consistent rate of 14.3 ha/year. Lodgepole pine ( Pinus contorta var. latifolia) was the most common tree species associated with encroachment. Invasion based on the number of established trees occurred at an exponential rate of 3.1%/year after 1890, with density increased by filling spaces adjacent to and between trees within the grassland vegetation. The rate of tree establishment increased to 4.4%/year after 1980, suggesting a change occurred in environmental conditions. Annual atmospheric temperatures increased 0.55 °C from 1929 to 2005 ( P < 0.001), with winter (December–February) and spring (March–May) temperatures accounting for most of the increase ( P < 0.001), whereas summer (June–August) temperatures slightly decreased ( P < 0.050, 0.34 °C) and precipitation increased ( P < 0.005, 30 mm). Cattle and elk ( Cervus elaphus) grazing was not considered a primary factor for explaining tree encroachment. Based on multidimensional scaling, lodgepole pine establishment was associated with warmer spring temperatures and greater fall (October–November) precipitation. A landscape devoid of wildfires, combined with greater moisture availability, and a longer frost-free season is likely conducive to the sustained establishment of coniferous trees and forest development within the Cypress Hills fescue grassland ecosystem. Long-term conservation of the fescue grasslands could be possible by reintroducing fire.

The Cypress Hills Formation (Upper Eocene to Miocene): a semi-arid braidplain deposit resulting from intrusive uplift

The Upper Eocene – Miocene Cypress Hills Formation of the Cypress Hills plateau, in southwestern Saskatchewan and southeastern Alberta, is interpreted as a braidplain deposit. The regional paleoslope dipped to the northeast, and the east–west distribution of outcrop exposes facies representing lateral variation across the slope of the braidplain. Overall, the average clast size of the deposits decreases from west to east, with western area sediments dominated by boulder-sized gravels deposited on longitudinal bars. The eastern outcrop area contains deposits of braided channels cut into and interbedded with finer interchannel material including lacustrine marlstones, silcretes, and debris-flow deposits, the latter commonly containing abundant fossils.The gravels of the Cypress Hills Formation are multicyclic; they were originally derived from the western ranges of the Rocky Mountains during Laramide orogenesis and later shed farther into the basin during rebound due to unloading of the Laramide thrusts by erosion. Most recent transport resulted from uplift by intrusive activity of the Sweetgrass Hills, the Bearpaw Mountains, and the Highwood Mountains in northern Montana. Transport from the uplifted source areas was largely restricted to valley-confined rivers with the braidplains beginning beyond the valley termini. The lateral extent of the gravel braidplain was limited by the position of valleys and resulted in the observed variation in facies. Climate, as indicated by the sedimentology, faunal assemblages, silcretes, and palynology, was semi-arid with seasonal rainfall.

Geomorphic analysis of upper Assam Plains and adjoining areas for hydrocarbon exploration

‘Terrain Analysis’ of the the Assam Plains and adjoining areas of the Naga foothills and Mikir hills plateau has been carried out using LANDSAT images and cartographic maps, essentially as an aid for planning seismic surveys for hydrocarbon exploration. The terrain is divisible into five geomorphic zones of distinct characters and processes of evolution. They are: i) Brahmaputra flood plains, ii) Assam Alluvial Plains, iii) Naga Piedmont plains, iv) Mikir Denudational hills, and v) Naga Structural Hills. A number of geomorphic anomalies have been identified in these zones. Maximum number of the anomalies occur in the piedmont zone which is considered to be most prospective since suitable hydrocarbon generation and entrapment conditions exist in that part of the basin. There dominant trends of lineaments striking ENE-WSW NW-SE and E-W are observed in the area in that order of extent and frequency. The last mentioned appears to be youngest which has off-setted even the Naga Thrust. Five distinct planation surfaces/summit levels have been identified in the Mikir as well as Naga hills. They are correlatable with the known unconformities at the top of basement, top of Barails, top of Girujan, top of Namsang and top of Dihing Formations. The subsurface lithology expected during shot hole drilling for seismic surveys has been predicted considering the process of evolution of each zone.

Quaternary events in the Elkwater Lake area of southeastern Alberta

New data necessitate revisions in the Quaternary chronology of the Elkwater Lake area. Relicts of post-Middle Miocene preglacial erosion surfaces descend to the north and south from the Middle Miocene depositional surface on the Cypress Hills plateau. Both sets of surfaces are marked by oxidized weathering zones, locally culminating in relicts of preglacial paleosols. Both surfaces are overlain by a loess replete with cryogenic imprints. Deposition of this loess with cryogenic imprints shortly predates arrival of the Green Lake glacier at its terminus.The Green Lake end moraine marks the maximum extent of Laurentide ice in this area. Features previously attributed to the older Elkwater glacier can be explained with reference to proglacial meltwater action associated with the Green Lake glacier. The concept of Elkwater drift is no longer valid.Younger loesses, called upper loess, mantle nonglaciated terrain and the Green Lake end moraine and began accumulating just before Glacier Peak tephra was deposited (ca. 12 000 years ago). Because there is no evidence of weathering on the Green Lake end moraine beneath the upper loess, Green Lake drift dates from the late Wisconsinan. Most of the upper loess was deposited during the early Holocene and some since the Mazama volcanic eruption, 6600 years ago.Elkwater Lake reached its highest postglacial level, i.e., at least 6.6 m above the present level, well after the Mazama eruption, before spilling across the Green Lake end moraine into the Ross Creek system. This event irrevocably changed the regimen of Ross Creek, probably to its confluence with the South Saskatchewan River, at Medicine Hat.

Fossil mammals of the Southfork Local Fauna (early Chadronian) of Saskatchewan

The Southfork Local Fauna, Cypress Hills Formation, Cypress Hills Plateau, southwestern Saskatchewan, is distinctly older than the nearby Calf Creek Local Fauna. Co-occurrence at Southfork of Hyracodon petersoni, Brachyhyops viensis, Leptomeryx cf. L. yoderi, and Leptomeryx cf. L. blacki indicates biostratigraphic correlation low in the early Chadronian. Presence of Oligocene local faunas of different ages strengthens the concept of a faunal succession in the Cypress Hills Formation, and emphasizes the importance of considering Cypress Hills assemblages locality by locality.

Lichens from Bathurst Inlet Region, Northwest Territories, Canada

Reported from Bathurst Inlet region in the central northern conti- nental arctic of North America are 214 species representing 223 taxa. The majority are circumpolar species, seven are western arctic, three are possibly eastern arctic. Pertusaria excludens is reported from the American arctic and Peltigera occiden- talis is confirmed for North America. New combinations are Aspicila arctica (Lynge) Thoms. and Aspicilia bennettii (Lynge) Thoms. Bathurst Inlet, located in the central northern edge of the continental arctic portion of North America, is important in providing information on the extent of distribution of the American arctic lichens, such as whether or not the ranges extend that far from the eastern arctic or represent easterly ranges of the Beringian, western arctic, elements in the flora. The comparative inaccessibility of this area has left its cryptogamic flora unstudied until now. The nearest lichen studies are those to the west at the Anderson River drainage (Ahti et al. 1973), to the south in the vicinity of Great Slave Lake (Thomson et al. 1969) and to the southeast in the Thelon River region (Scotter & Thomson 1966). Bathurst Inlet is on the mainland of the western Canadian Arctic, roughly between the mouth of the Mackenzie River and Boothia Peninsula. The inlet is a complex submerged valley that penetrates from the east end of Coronation Gulf in a southeasterly direction about 200 km into the barren grounds. The Bathurst Inlet area lies wholly within the physiographic division of the Canadian Shield. Bird and Bird (1961) described the physiographic regions defined below. The Inlet itself and its adjacent lowlands they regard as a long narrow southward extension of the Coronation Gulf lowlands penetrating the Canadian Shield, which forms plateaus to east and west: the Tree River Uplands, Wilberforce Hills and Contwoyto Plateau to the west, and the Bathurst and Buchan Uplands to the east. The Contwoyto Plateau is in general high (450 m elev.), gently rolling, and mantled with drift, with the Wilberforce Hills as its rough dissected edge. The Tree River Upland is a lower, dissected granite plateau of smoothed rock-knob hills penetrated by deep valleys into which drift deposits have been washed. The Buchan Upland northeast of Bathurst Inlet is similar to the Tree River Upland although somewhat lower, a granite peneplain eroded into bare rock-knob hills. Drift washed into the valleys supports damp tundra, although many valleys are blocked, forming elongated or cruciform lakes. The Bathurst Upland to the southeast corresponds to the Contwoyto Plateau; near Gordon Bay this upland surface is deeply dissected. Farther south, to the east of Western River, there is less dissection, but both areas are rocky. The

Middle Miocene Mammals from the Cypress Hills, Canada

Parahippus sp., Hypohippus equinus, and Camelidae, gen. et sp. indet. have been collected from the Cypress Hills Formation in Saskatchewan, near the top of the section. The combination of taxa indicates a Hemingfordian (Middle Miocene) age for some deposits. I suggest a limited amount of Middle Miocene deposition before the uplift of the Cypress Hills Plateau.

Ecology of the Great Sandhills and Cypress Hills Plateau

Ecology of the Great Sandhills and Cypress Hills Plateau