Geologic map of the Rio Puerco quadrangle, Bernalillo and Valencia Counties, New Mexico

The Rio Puerco quadrangle is located southwest of Albuquerque in central
New Mexico and covers part of the western part of the Isleta Reservation.
The U.S. Geological Survey, the New Mexico Bureau of Geology and Mineral
Resources, and the University of New Mexico have conducted geologic
mapping on the Isleta Reservation and vicinity as part of the Middle Rio
Grande Basin Project. The map area contains surficial deposits, calcic
soils, fluvial deposits of the Rio Puerco, deposits of the Santa Fe Group,
and three volcanic fields. The area is characterized by predominantly
north-trending normal faults with generally down-to-the-east movement.
Post-Santa Fe Group deposits are composed of surficial deposits
(Pleistocene-Holocene) and fluvial deposits of the Rio Puerco
(Pleistocene-Holocene). The surficial deposits are divided into eolian,
alluvial, colluvial, and landslide deposits. The fluvial deposits of the
Rio Puerco consist of four terrace and present channel deposits.
The Santa Fe Group is divided into lower and upper parts. The lower part
of the Santa Fe Group is exposed near the southwestern corner of the study
area where deposits consist of reddish-brown mudstone and sandstone
correlated to the Popotosa Formation (Unit 1) of Lozinsky and Tedford
(1991). They interpreted deposition of the unit in a basin-floor playa
setting. The Popotosa Formation is in fault contact to the east with
deposits of the upper Santa Fe Group. The upper Santa Fe Group is derived
from major tributary fluvial systems (ancestral Rio Puerco Puerco and
possibly the Rio San Jose drainages) draining the adjacent Colorado
Plateau and Sierra Nacimiento and correlated to parts of Kelley's (1977)
Ceja Formation of the Santa Fe Group and equivalent to Machette's (1978)
Sierra Ladrones Formation, Connell's Arroyo Ojito Formation (Connell and
others, 1999, and Maldonado's lithofacies of the Isleta Reservation
(Maldonado and Atencio,1998a, b). The group also locally includes a fine-
grained unit (lower Pleistocene) referred to here as the sand, silt, and
clay of Chavez Grant (Qsc). The Ceja Formation of the Santa Fe Group as
defined here is divided into the following units in descending
stratigraphic order: (1) upper sand and gravel unit (upper Pliocene), (2)
middle silt, sand, and clay unit (upper Pliocene), and (3) lower sand and
gravel unit (Pliocene).
The three volcanic fields in the map area are: (1) basalt of Cat Hills,
dated at 98-110 ka and composed of seven lava flows and four cinder cones;
the flows overlie calcic soils that overlie the upper sand and gravel unit
of the Ceja Formation; (2) lava flow of Cat Mesa, dated at about 3 Ma and
interfingers with the upper part of the Ceja Formation; (3) diabase of
Mohinas Mountain, dated at 8.3 Ma (Baldridge and others, 1987) and
intrudes the Popotosa Formation.
Numerous high-angle faults cut the area but are mostly buried. The faults
generally trend north but deviate to the northwest and northeast. The
major normal faults are the Cat Mesa and Mohinas Mountain faults.

普埃尔科河地质图幅（Rio Puerco quadrangle）坐落于新墨西哥州中部阿尔伯克基西南侧，覆盖伊斯莱塔保留地（Isleta Reservation）西部部分区域。作为中里奥格兰德盆地项目（Middle Rio Grande Basin Project）的组成部分，美国地质调查局（U.S. Geological Survey）、新墨西哥州地质与矿产资源局以及新墨西哥大学已对伊斯莱塔保留地及其周边区域开展了地质填图工作。本图幅范围内包含地表沉积层（surficial deposits）、钙积土（calcic soils）、普埃尔科河（Rio Puerco）河流沉积（fluvial deposits）、圣达菲群（Santa Fe Group）沉积以及三处火山岩区（volcanic fields）。该区域以走向北的正断层（normal faults）为主要特征，多数断层表现为东盘下降。
圣达菲群后期沉积（Post-Santa Fe Group deposits）由地表沉积层（更新世-全新世（Pleistocene-Holocene））与普埃尔科河河流沉积（更新世-全新世（Pleistocene-Holocene））构成。地表沉积层可进一步划分为风成沉积（eolian deposits）、冲积沉积（alluvial deposits）、坡积沉积（colluvial deposits）与滑坡沉积（landslide deposits）。普埃尔科河的河流沉积包含4处阶地沉积（terrace deposits）与现代河道沉积（present channel deposits）。
圣达菲群可划分为上下两部分。圣达菲群下部出露于研究区西南角附近，其沉积物为红棕色泥岩（reddish-brown mudstone）与砂岩（sandstone），可对比于洛津斯基与特德福德（1991）定义的波波托萨组（Popotosa Formation，单元1）。洛津斯基与特德福德将该单元的沉积环境解释为盆地底部干盐湖环境。波波托萨组东侧以断层接触（fault contact）关系与圣达菲群上部沉积相接。
圣达菲群上部主要源自汇入相邻科罗拉多高原（Colorado Plateau）与纳西米恩托山（Sierra Nacimiento）的主要支流河流系统（major tributary fluvial systems），即古普埃尔科河（ancestral Rio Puerco）与可能的圣何塞河（Rio San Jose）汇水系统，可对比于凯利（1977）定义的圣达菲群塞哈组（Ceja Formation）的相关层位，同时等效于马谢特（1978）的塞拉拉德龙斯组（Sierra Ladrones Formation）以及康奈尔等（1999）的奥希托溪组（Arroyo Ojito Formation），还包含马尔多纳多与阿滕西奥（1998a、b）定义的伊斯莱塔保留地岩相（lithofacies）。该群局部还包含一处细粒单元（fine-grained unit），形成于早更新世（lower Pleistocene），本文中将其命名为查韦斯格兰特砂、粉砂与黏土层（Qsc）。本文所定义的圣达菲群塞哈组按地层降序（descending stratigraphic order）划分为以下单元：(1) 上部砂卵砾石层（upper sand and gravel unit），形成于上新世晚期（upper Pliocene）；(2) 中部粉砂、砂与黏土层（middle silt, sand, and clay unit），形成于上新世晚期；(3) 下部砂卵砾石层（lower sand and gravel unit），形成于上新世（Pliocene）。
本图幅范围内的三处火山岩区分别为：(1) 卡特山玄武岩（basalt of Cat Hills），年代为98~110 ka，由7条熔岩流（lava flows）与4座火山渣锥（cinder cones）构成，其熔岩流覆盖于钙积土之上，而钙积土又覆于塞哈组上部砂卵砾石层之上；(2) 卡特台地熔岩流（lava flow of Cat Mesa），年代约为3 Ma，与塞哈组上部层位互层；(3) 莫希纳斯山辉绿岩（diabase of Mohinas Mountain），年代为8.3 Ma（鲍尔德里奇等，1987），侵入于波波托萨组之中。
区域内发育多条高角度断层（high-angle faults），但多数被掩埋。这些断层整体走向北，局部偏转至北西向与北东向。主要正断层为卡特台地断层与莫希纳斯山断层。