Structural Study of Faihaa Oil Field in Basra South of Iraq

This study used structural contour maps to carry out the geometrical analysis for Faihaa structure in Basra southern Iraq. The study used row data of well logs and structural maps while Softwares were Didger 4, Stereonet v.11 and Petrel 2017 Faihaa Oil Field is located at an eastern part of the Mesopotamian Zone within the Zubair Subzone, characterized by subsurface geological structures covered by Quaternary sediments. These structures are oriented in the NW-SE direction in the eastern part of the band and the N-S direction in the southern region, and some in the direction NE-SW. The Faihaa Oil Field shows that is an Anticline structure. The average dip value of an axial surface is 89.7° while the plunge of hinge line between 4–4.2 in North-West direction referred to that Faihaa Structure is upright and gentle fold. Based on the Thickness ratio and axial angle, the Faihaa Structure is thickened Fold. The eastern limb of the fold is longer than the western limb, so Faihaa Oil Field is an asymmetrical structure. The difference in dimensions (5<Length / Width < 2) confirmed the brachy fold of the Faihaa structure.

Age constraints on surface deformation recorded by fossil shorelines at Cape Range, Western Australia: Comment

Sandstrom et al. (2020) present new elevation and age data for a flight of four marine terraces preserved along the western limb of the Cape Range anticline in western Australia. Their interpretation of these data provides an alternative estimate for the amount of tectonic deformation that has occurred since terrace formation. They conclude that less tectonic uplift has occurred in the region than previously reported and posit that their study provides a template for reducing the uncertainty associated with last interglacial paleoshoreline reconstructions.

Deformation and structural evolution of metamorphic complexes of the Taldyk antiform in the East Mugodzhar zone of Urals (West Kazakhstan)

The study is focused on mesostructural folded parageneses of the Taldyk antiform (a.k.a. Taldyk block) located in the East Mugodzhar zone. The sequence of their formation is established; the structural evolution of the study area is investigated, and four stages of deformation are identified. The NW-trending folds F1 with SE-vergence formed during the first stage of deformation, DI. The geodynamics and timeline of this stage remain unclear. The W-E-trending folds F2 with E-vergence are related to tectonic movements that took place at stage DII. In the western limb of the antiform, stage DII is evidenced by folds overturned towards the south-east. In the eastern limb, folds plunge to the east and northeast. These fold structures are probably related to the Devonian subduction-obduction processes. At stage DIII, thrusting of the Taldyk antiform over the West Mugodzhar zone and folding F3 with W-vergence is related to the Ural continental collision in the Late Paleozoic, which completed the geodynamic evolution of the Ural paleo-ocean. At stage DIV, postcollisional shearing is evidenced by folds F4 with steeply dipping hinges, which completed the structural evolution of the study area.

Bulk rock geochemistry of a swarm of orangeite dykes intersecting the Western Limb of the Bushveld Complex

&lt;p&gt;The Western Limb of the Bushveld Complex hosts a vast, recently documented swarm of orangeite dykes that are significantly younger (177-132 Ma; Hughes et al., in prep.) than the c. 2.06 Ga Bushveld lithologies they intrude. Orangeite dykes are hybrid igneous rocks that form from very low-degree partial melting deep within the sub-cratonic lithospheric mantle (SCLM) and upon ascent entrain foreign material (primarily mantle xenocrysts). Thus, they can be used to probe the composition of and processes within the ancient lithospheric mantle. Whereas similar orangeite dyke swarms in South Africa typically span &lt; 10 km, the considerable size of this swarm (&gt; 50 km along strike and ~10 km wide) and number of closely-spaced dykes offers a unique opportunity to investigate the Kaapvaal SCLM on an unprecedented spatial scale. In this contribution we present the whole rock major and trace element abundances, and the radiogenic isotope compositions of the dykes.&lt;/p&gt;&lt;p&gt;The Bushveld orangeites are mafic-ultramafic (whole rock Mg# of 65 to 88) and have overlapping major element abundances to other Kaapvaal orangeites, with significant similarity to the coeval Swartruggens orangeite dyke swarm (Coe et al., 2008). Trace element abundances of the Bushveld dykes are less consistent with Kaapvaal orangeite variability, displaying greater ranges in concentrations of certain elements (e.g. La, Th, Ba) despite being generally relatively depleted in these elements.&lt;/p&gt;&lt;p&gt;Radiogenic isotope compositions of the orangeites typically confine to the global orangeite variability, with radiogenic Sr (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr&lt;sub&gt;i&lt;/sub&gt;&lt;sup&gt;&lt;/sup&gt;of 0.70642 to 0.70787) and unradiogenic Hf compositions (&amp;#603;Hf&lt;sub&gt;i &lt;/sub&gt;of -18.3 to -8.3). Initial Nd compositions are generally unradiogenic (&amp;#603;Nd&lt;sub&gt;i&lt;/sub&gt; of -11.6 to -9.0), conforming to values of global orangeites, however three samples display elevated initial Nd (&amp;#603;Nd&lt;sub&gt;i&lt;/sub&gt; of -5.4 to -0.4) and plot in a similar Sr-Nd compositional space to Kaapvaal transitional kimberlites.&lt;/p&gt;&lt;p&gt;Using the trace element variations and radiogenic isotope compositions we aim to investigate the geochemistry of the mantle source regions tapped by the orangeites and whether we can identify changes in source characteristics on a swarm scale.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Coe, N. et al. (2008) Cont. Min. Pet. 156(5). 627-652.&lt;/p&gt;&lt;p&gt;Hughes, H.S.R. et al. (in prep).&lt;/p&gt;

Bedrock geology, Mount Hare, Yukon, NTS 116-I/9

The Mount Hare map area extends across the western limb of the Richardson anticlinorium in the southern Richardson Mountains, northern Yukon. It is underlain by four Paleozoic sedimentary successions: middle Cambrian Slats Creek Formation, middle Cambrian to Early Devonian Road River Group, Devonian Canol Formation, and Late Devonian to Carboniferous Imperial and Tuttle formations. The Richardson trough depositional setting of the first three successions is succeeded by a deep-marine, turbiditic Ellesmerian orogenic foredeep setting for the Imperial-Tuttle succession. The carbonate-dominated Road River Group defines a west-dipping homocline which is transected by oblique transverse faults in its upper part. In the overlying Imperial-Tuttle succession, map-scale folds can be defined where shales are interbedded with thick persistent sandstone units. The structural geometry reflects Cretaceous-Cenozoic regional Cordilleran tectonism.

G107.0+9.0: a new large optically bright, radio, and X-Ray faint galactic supernova remnant in Cepheus

ABSTRACT Wide-field H α images of the Galactic plane have revealed a new supernova remnant (SNR) nearly 3 deg in diameter centred at l = 107.0, b = +9.0. Deep and higher resolution H α and [O iii] 5007 Å images show dozens of H α filaments along the remnant’s northern, western, and southwestern limbs, but few [O iii] bright filaments. The nebula is well detected in the H α Virginia Tech Spectral-Line Survey images, with many of its brighter filaments even visible on Digital Sky Survey images. Low-dispersion spectra of several filaments show either Balmer dominated, non-radiative filaments, or the more common SNR radiative filaments with [S II]/H α ratios above 0.5, consistent with shock-heated line emission. Emission line ratios suggest shock velocities ranging from ≤70 km s−1 along its western limb to ≃ 100 km s−1 along its northwestern boundary. While no associated X-ray emission is seen in ROSAT images, faint 1420 MHz radio emission appears coincident with its western and northern limbs. Based on an analysis of the remnant’s spatially resolved H α and [O iii] emissions, we estimate the remnant’s distance at ∼1.5−2.0 kpc implying a physically large (dia. = 75−100 pc) and old (90−110 × 103 yr) SNR in its post-Sedov radiative phase of evolution expanding into a low-density interstellar medium (n0 = 0.05−0.2 cm−3) and lying some 250−300 pc above the Galactic plane.

Supplemental Material: Quantifying shortening across the central Appalachian fold-thrust belt, Virginia and West Virginia, USA: Reconciling grain-, outcrop-, and map-scale shortening

Plate 1. (A and B) Balanced (A) and restored (B) cross section A-A' extending from the eastern Great Valley westward to the Burning Spring anticline (Fig. 1). Total deformed length (274 km) and undeformed restored length (346 km) are measured from a pin line east of the extent of documented map-scale shortening on the Appalachian Plateau, resulting in 78 km (23%) total shortening. (C) As shown, shortening in Upper Devonian through Permian rocks assumes 10% layer-parallel shortening (LPS) in the Appalachian Plateau and across the Appalachian front (to thick vertical bar) and 25% LPS in the Valley and Ridge (region between thick vertical bars). Shortening in the Great Valley requires 35% LPS, compared to the >50% LPS measured in that region (Wright and Platt, 1982). Cross sections drawn with no vertical exaggeration; Circled numbers—duplex numbers; Fm–Formation; Gp—Group. Plate 2. Geologic cross section divided into 16 sequentially numbered intervals (circled numbers above the cross section) spanning from the western limb of the Burning Springs anticline eastward to the Great Valley. Locations of each of the 40 samples used to constrain grain-scale layer-parallel shortening (LPS) are shown as small white dots projected into the line of section; calculated LPS (as a percentage) are shown above each sample. Mean LPS values for each interval are summarized in Table 2. (A) Cross section constructed to minimize the amount of unit thickness variation in the Reedsville-Martinsburg Formations. Balancing this section requires 10% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. (B) Cross section constructed to minimize contributions from outcrop-scale shortening. Balancing this section requires 5% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. Cross sections drawn with no vertical exaggeration; circled numbers—duplex numbers; Fm—Formation; Gp—Group.

Supplemental Material: Quantifying shortening across the central Appalachian fold-thrust belt, Virginia and West Virginia, USA: Reconciling grain-, outcrop-, and map-scale shortening

Plate 1. (A and B) Balanced (A) and restored (B) cross section A-A' extending from the eastern Great Valley westward to the Burning Spring anticline (Fig. 1). Total deformed length (274 km) and undeformed restored length (346 km) are measured from a pin line east of the extent of documented map-scale shortening on the Appalachian Plateau, resulting in 78 km (23%) total shortening. (C) As shown, shortening in Upper Devonian through Permian rocks assumes 10% layer-parallel shortening (LPS) in the Appalachian Plateau and across the Appalachian front (to thick vertical bar) and 25% LPS in the Valley and Ridge (region between thick vertical bars). Shortening in the Great Valley requires 35% LPS, compared to the >50% LPS measured in that region (Wright and Platt, 1982). Cross sections drawn with no vertical exaggeration; Circled numbers—duplex numbers; Fm–Formation; Gp—Group. Plate 2. Geologic cross section divided into 16 sequentially numbered intervals (circled numbers above the cross section) spanning from the western limb of the Burning Springs anticline eastward to the Great Valley. Locations of each of the 40 samples used to constrain grain-scale layer-parallel shortening (LPS) are shown as small white dots projected into the line of section; calculated LPS (as a percentage) are shown above each sample. Mean LPS values for each interval are summarized in Table 2. (A) Cross section constructed to minimize the amount of unit thickness variation in the Reedsville-Martinsburg Formations. Balancing this section requires 10% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. (B) Cross section constructed to minimize contributions from outcrop-scale shortening. Balancing this section requires 5% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. Cross sections drawn with no vertical exaggeration; circled numbers—duplex numbers; Fm—Formation; Gp—Group.

Supplemental Material: Quantifying shortening across the central Appalachian fold-thrust belt, Virginia and West Virginia, USA: Reconciling grain-, outcrop-, and map-scale shortening

Plate 1. (A and B) Balanced (A) and restored (B) cross section A-A' extending from the eastern Great Valley westward to the Burning Spring anticline (Fig. 1). Total deformed length (274 km) and undeformed restored length (346 km) are measured from a pin line east of the extent of documented map-scale shortening on the Appalachian Plateau, resulting in 78 km (23%) total shortening. (C) As shown, shortening in Upper Devonian through Permian rocks assumes 10% layer-parallel shortening (LPS) in the Appalachian Plateau and across the Appalachian front (to thick vertical bar) and 25% LPS in the Valley and Ridge (region between thick vertical bars). Shortening in the Great Valley requires 35% LPS, compared to the >50% LPS measured in that region (Wright and Platt, 1982). Cross sections drawn with no vertical exaggeration; Circled numbers—duplex numbers; Fm–Formation; Gp—Group. Plate 2. Geologic cross section divided into 16 sequentially numbered intervals (circled numbers above the cross section) spanning from the western limb of the Burning Springs anticline eastward to the Great Valley. Locations of each of the 40 samples used to constrain grain-scale layer-parallel shortening (LPS) are shown as small white dots projected into the line of section; calculated LPS (as a percentage) are shown above each sample. Mean LPS values for each interval are summarized in Table 2. (A) Cross section constructed to minimize the amount of unit thickness variation in the Reedsville-Martinsburg Formations. Balancing this section requires 10% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. (B) Cross section constructed to minimize contributions from outcrop-scale shortening. Balancing this section requires 5% outcrop-scale shortening between the Elkins Valley anticline and the boundary between the Valley and Ridge and Great Valley. Cross sections drawn with no vertical exaggeration; circled numbers—duplex numbers; Fm—Formation; Gp—Group.