Puerto Rico and the northern Virgin Islands together preserve a unique archive of island arc construction and plate margin deformation along the northeastern edge of the Caribbean plate. In Eocene times, arc-continent collision of the Caribbean plate and the North American plate led to transpressional deformation along two major fault systems in Puerto Rico, resulting in an island-wide depositional hiatus. Although styles and kinematics of this deformational event are seemingly well understood, the lack of chronologic constraints have left uncertainties related to the timing of inception and activity, the magnitude of crustal exhumation, and the character of deformation (i.e., progressive or polyphase). New zircon and apatite (U-Th)/He ages reveal that deformation associated with arc-continent collision started in the early Eocene (ca. 52 Ma) and ended in the early Oligocene (ca. 29 Ma). Over this 23 m.y. time frame, deformation was not restricted to major faults, instead it propagated gradually eastward, with punctuated episodes of vertical exhumation in the early Eocene (ca. 52–34 Ma) and late Eocene (ca. 36–29 Ma). In contrast, the northern Virgin Islands experienced rapid cooling and exhumation in the early Miocene (ca. 24–21 Ma) associated with the extensional opening of the Anegada Passage. The modeled thermal histories for the central and northeastern part of Puerto Rico indicate collision-related peak transpressional deformation between 36 and 29 Ma and an average exhumation rate 0.9 ± 0.6 km/m.y. These results represent the first direct constraints on the timing and magnitude of collisional exhumation and offer insights into the deformational evolution of the northeastern edge of the Caribbean plate.

中文翻译：

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与东北加勒比板块始新世弧-陆-陆碰撞有关的渐进发掘和变形的时间和大小

波多黎各和北部维尔京群岛共同保存着独特的弧形构造和沿加勒比板块东北边缘的板块边缘变形的档案。在始新世时期，加勒比板块和北美板块的弧线大陆碰撞导致波多黎各的两个主要断层系统发生了超压变形，导致了全岛范围内的沉积裂隙。尽管这种变形事件的样式和运动学看似很容易理解，但是由于缺乏时间顺序上的限制，使得不确定性与开始和活动的时间，地壳发掘的幅度以及变形的特征（即渐进或多相）有关。新的锆石和磷灰石（U-Th）/ He年龄揭示了与弧-陆碰撞相关的形变始于始新世早期（ca. 52 Ma）结束于渐新世（大约29 Ma）。在这23个时间段内，变形并不仅限于主要断层，而是逐渐向东传播，在始新世早期（大约52-34 Ma）和始新世晚期（大约36-29 Ma）出现了垂直回火的断断续续的现象。 。相比之下，北部的维尔京群岛在中新世早期（约24-21 Ma）经历了快速的冷却和掘尸，这与Anegada通道的扩展开放有关。波多黎各中部和东北部的模拟热史表明，与碰撞有关的峰压变形在36和29 Ma之间，平均掘尸速率为0.9±0.6 km / my